None Computing title Cisco IOS Router RTR Security Technical Implementation Guide version 3 releaseinfo Release: 4 Vuln_Num V-216551 Rule_ID SV-216551r1117236_rule Severity medium Rule_Title The Cisco router must be configured to enforce approved authorizations for controlling the flow of information within the network based on organization-defined information flow control policies. Vuln_Discuss Information flow control regulates where information is allowed to travel within a network and between interconnected networks. The flow of all network traffic must be monitored and controlled so it does not introduce any unacceptable risk to the network infrastructure or data. Information flow control policies and enforcement mechanisms are commonly employed by organizations to control the flow of information between designated sources and destinations (e.g., networks, individuals, and devices) within information systems. Enforcement occurs, for example, in boundary protection devices (e.g., gateways, routers, guards, encrypted tunnels, and firewalls) that employ rule sets or establish configuration settings that restrict information system services, provide a packet filtering capability based on header information, or provide a message filtering capability based on message content (e.g., implementing key word searches or using document characteristics). Check_Content This requirement is not applicable for the DODIN Backbone. If Virtual Routing and Forwarding (VRF) is used to segment traffic and force traffic to traverse through next generation firewalls with ACLs, this requirement is not applicable. Review the router configuration to verify that Access Control Lists (ACLs) are configured to allow or deny traffic for specific source and destination addresses as well as ports and protocols. For example, the configuration below will allow only printer traffic into subnet 10.1.23.0/24 and SQL traffic into subnet 10.1.24.0/24. ICMP is allowed for troubleshooting and OSPF is the routing protocol used within the network. interface GigabitEthernet1/1 description link to core ip address 10.1.12.2 255.255.255.0 ip access-group FILTER_SERVER_TRAFFIC in … … … ip access-list extended FILTER_SERVER_TRAFFIC permit tcp any 10.1.23.0 0.0.0.255 eq lpd 631 9100 permit tcp any 10.1.24.0 0.0.0.255 eq 1433 1434 4022 permit icmp any any permit ospf any any deny ip any any If the router is not configured to enforce approved authorizations for controlling the flow of information within the network based on organization-defined information flow control policies, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure ACLs to allow or deny traffic for specific source and destination addresses as well as ports and protocols between various subnets as required. The commands used below were used to create the configuration as shown in the check content. R5(config)#ip access-list extended FILTER_SERVER_TRAFFIC R5(config-ext-nacl)#permit tcp any 10.1.23.0 0.0.0.255 eq 515 631 9100 R5(config-ext-nacl)#permit tcp any 10.1.24.0 0.0.0.255 eq 1433 1434 4022 R5(config-ext-nacl)#permit icmp any any R5(config-ext-nacl)#permit ospf any any R5(config-ext-nacl)#deny ip any any R5(config-ext-nacl)#exit R5(config)#interface GigabitEthernet1/1 R5(config-if)#ip access-group FILTER_SERVER_TRAFFIC in Not_Reviewed Vuln_Num V-216555 Rule_ID SV-216555r1007824_rule Severity medium Rule_Title The Cisco router must be configured to enable routing protocol authentication using FIPS 198-1 algorithms with keys not exceeding 180 days of lifetime. Vuln_Discuss A rogue router could send a fictitious routing update to convince a site's perimeter router to send traffic to an incorrect or even a rogue destination. This diverted traffic could be analyzed to learn confidential information about the site's network or used to disrupt the network's ability to communicate with other networks. This is known as a "traffic attraction attack" and is prevented by configuring neighbor router authentication using FIPS 198-1 algorithms for routing updates. If the keys used for authentication are guessed, the malicious user could create havoc within the network by advertising incorrect routes and redirecting traffic. Some routing protocols allow the use of key chains for authentication. A key chain is a set of keys that is used in succession, with each having a lifetime of no more than 180 days. Changing the keys frequently reduces the risk of them eventually being guessed. If a time period occurs during which no key is activated, neighbor authentication cannot occur, and therefore routing updates will fail. Check_Content Review the router configuration using the configuration examples below for BGP and OSPF. Certain older protocols supporting only MD5 will incur a permanent finding for those protocols as MD5 is not FIPS compliant. Note: The 180-day key lifetime is Not Applicable for the DODIN Backbone. The remainder of the requirement still applies. Verify that neighbor router authentication is enabled for all routing protocols. If neighbor authentication is not enabled this is a finding. Verify that authentication is configured to use FIPS 198-1 message authentication algorithms. If the routing protocol authentication is not configured to use FIPS 198-1 algorithms this is a finding. Verify that the protocol key lifetime is configured to not exceed 180 days. If any protocol key lifetime is configured to exceed 180 days this is a finding. BGP Example: key chain <KEY-CHAIN-NAME> tcp key <KEY-ID> send-id <ID> recv-id <ID> cryptographic-algorithm hmac-sha256 key-string <KEY> accept-lifetime 00:00:00 Jan 1 2022 duration 180 send-lifetime 00:00:00 Jan 1 2022 duration 180 ! ! router bgp <ASN> no synchronization bgp log-neighbor-changes neighbor x.x.x.x remote-as <ASN> neighbor x.x.x.x ao <KEY-CHAIN-NAME> Note: TCP-AO is used to replace MD5 in BGP authentication. OSPF Example: key chain OSPF_KEY_CHAIN key 1 key-string xxxxxxx send-lifetime 00:00:00 Jan 1 2018 23:59:59 Mar 31 2018 accept-lifetime 00:00:00 Jan 1 2018 01:05:00 Apr 1 2018 cryptographic-algorithm hmac-sha-256 key 2 key-string yyyyyyy send-lifetime 00:00:00 Apr 1 2018 23:59:59 Jun 30 2018 accept-lifetime 23:55:00 Mar 31 2018 01:05:00 Jul 1 2018 cryptographic-algorithm hmac-sha-256 … … … interface GigabitEthernet0/1 ip address x.x.x.x 255.255.255.0 ip ospf authentication key-chain OSPF_KEY_CHAIN Fix_Text Configure routing protocol authentication to use a NIST-validated FIPS 198-1 message authentication code algorithm with keys not exceeding 180 days of lifetime as shown in the examples. BGP Example: Step 1: Configure a keychain using a FIPS 198-1 algorithm with a key duration not exceeding 180 days. key chain <KEY-CHAIN-NAME> tcp key <KEY-ID> send-id <ID> recv-id <ID> cryptographic-algorithm hmac-sha256 key-string <KEY> accept-lifetime 00:00:00 Jan 1 2022 duration 180 send-lifetime 00:00:00 Jan 1 2022 duration 180 ! Step 2: Configure BGP autonomous system to use the keychain for authentication. router bgp <ASN> no synchronization bgp log-neighbor-changes neighbor x.x.x.x remote-as <ASN> neighbor x.x.x.x ao <KEY-CHAIN-NAME> OSPF Example: Step 1: Configure a keychain using a FIPS 198-1 algorithm with a key duration not exceeding 180 days. key chain OSPF_KEY_CHAIN key 1 key-string xxxxxxx send-lifetime 00:00:00 Jan 1 2018 23:59:59 Mar 31 2018 accept-lifetime 00:00:00 Jan 1 2018 01:05:00 Apr 1 2018 cryptographic-algorithm hmac-sha-256 key 2 key-string yyyyyyy send-lifetime 00:00:00 Apr 1 2018 23:59:59 Jun 30 2018 accept-lifetime 23:55:00 Mar 31 2018 01:05:00 Jul 1 2018 cryptographic-algorithm hmac-sha-256 Step 2: Configure OSPF to use the keychain for authentication. interface GigabitEthernet0/1 ip address x.x.x.x 255.255.255.0 ip ospf authentication key-chain OSPF_KEY_CHAIN Not_Reviewed Vuln_Num V-216556 Rule_ID SV-216556r1117237_rule Severity low Rule_Title The Cisco router must be configured to have all inactive interfaces disabled. Vuln_Discuss An inactive interface is rarely monitored or controlled and may expose a network to an undetected attack on that interface. Unauthorized personnel with access to the communication facility could gain access to a router by connecting to a configured interface that is not in use. If an interface is no longer used, the configuration must be deleted and the interface disabled. For sub-interfaces, delete sub-interfaces that are on inactive interfaces and delete sub-interfaces that are themselves inactive. If the sub-interface is no longer necessary for authorized communications, it must be deleted. Check_Content Review the router configuration and verify that inactive interfaces have been disabled as shown below. interface GigabitEthernet3 shutdown ! interface GigabitEthernet4 shutdown If an interface is not being used but is configured or enabled, this is a finding. Fix_Text Disable all inactive interfaces as shown below. R4(config)#interface GigabitEthernet3 R4(config-if)#shutdown R4(config)#interface GigabitEthernet4 R4(config-if)#shutdown Not_Reviewed Vuln_Num V-216559 Rule_ID SV-216559r856180_rule Severity medium Rule_Title The Cisco router must not be configured to have any zero-touch deployment feature enabled when connected to an operational network. Vuln_Discuss Network devices that are configured via a zero-touch deployment or auto-loading feature can have their startup configuration or image pushed to the device for installation via TFTP or Remote Copy (rcp). Loading an image or configuration file from the network is taking a security risk because the file could be intercepted by an attacker who could corrupt the file, resulting in a denial of service. Check_Content Review the device configuration to determine if auto-configuration or zero-touch deployment via Cisco Networking Services (CNS) is enabled. Auto-configuration example version 15.0 service config … … … boot-start-marker boot network tftp://x.x.x.x/R5-config boot-end-marker CNS Zero-Touch Example cns trusted-server config x.x.x.x cns trusted-server image x.x.x.x cns config initial x.x.x.x 80 cns exec 80 cns image If a configuration auto-loading feature or zero-touch deployment feature is enabled, this is a finding. Note: Auto-configuration or zero-touch deployment features can be enabled when the router is offline for the purpose of image loading or building out the configuration. In addition, this would not be applicable to the provisioning of virtual routers via a software-defined network (SDN) orchestration system. Fix_Text Disable configuration auto-loading if enabled using the following commands. R8(config)#no boot network R8(config)#no service config Disable CNS zero-touch deployment if enabled as shown in the example below. R2(config)#no cns config initial R2(config)#no cns exec R2(config)#no cns image R2(config)#no cns trusted-server config x.x.x.x R2(config)#no cns trusted-server image x.x.x.x Not_Reviewed Vuln_Num V-216560 Rule_ID SV-216560r991835_rule Severity high Rule_Title The Cisco router must be configured to protect against or limit the effects of denial-of-service (DoS) attacks by employing control plane protection. Vuln_Discuss The Route Processor (RP) is critical to all network operations because it is the component used to build all forwarding paths for the data plane via control plane processes. It is also instrumental with ongoing network management functions that keep the routers and links available for providing network services. Any disruption to the RP or the control and management planes can result in mission-critical network outages. A DoS attack targeting the RP can result in excessive CPU and memory utilization. To maintain network stability and RP security, the router must be able to handle specific control plane and management plane traffic that is destined to the RP. In the past, one method of filtering was to use ingress filters on forwarding interfaces to filter both forwarding path and receiving path traffic, as well as limiting traffic destined to the device. However, this method does not scale well as the number of interfaces grows and the size of the ingress filters grows. Control plane policing increases the security of routers and multilayer switches by protecting the RP from unnecessary or malicious traffic. Filtering and rate limiting the traffic flow of control plane packets can be implemented to protect routers against reconnaissance and DoS attacks, allowing the control plane to maintain packet forwarding and protocol states despite an attack or heavy load on the router or multilayer switch. Check_Content Review the Cisco router configuration to verify that it is compliant with this requirement. Step 1: Verify traffic types have been classified based on importance levels. The following is an example configuration: class-map match-all CoPP_CRITICAL match access-group name CoPP_CRITICAL class-map match-any CoPP_IMPORTANT match access-group name CoPP_IMPORTANT match protocol arp class-map match-all CoPP_NORMAL match access-group name CoPP_NORMAL class-map match-any CoPP_UNDESIRABLE match access-group name CoPP_UNDESIRABLE class-map match-all CoPP_DEFAULT match access-group name CoPP_DEFAULT Step 2: Review the Access Control Lists (ACLs) referenced by the class maps to determine if the traffic is being classified appropriately. The following is an example configuration: ip access-list extended CoPP_CRITICAL remark our control plane adjacencies are critical permit ospf host [OSPF neighbor A] any permit ospf host [OSPF neighbor B] any permit pim host [PIM neighbor A] any permit pim host [PIM neighbor B] any permit pim host [RP addr] any permit igmp any 224.0.0.0 15.255.255.255 permit tcp host [BGP neighbor] eq bgp host [local BGP addr] permit tcp host [BGP neighbor] host [local BGP addr] eq bgp deny ip any any ip access-list extended CoPP_IMPORTANT permit tcp host [TACACS server] eq tacacs any permit tcp [management subnet] 0.0.0.255 any eq 22 permit udp host [SNMP manager] any eq snmp permit udp host [NTP server] eq ntp any deny ip any any ip access-list extended CoPP_NORMAL remark we will want to rate limit ICMP traffic deny icmp any host x.x.x.x fragments permit icmp any any echo permit icmp any any echo-reply permit icmp any any time-exceeded permit icmp any any unreachable deny ip any any ip access-list extended CoPP_UNDESIRABLE remark other management plane traffic that should not be received permit udp any any eq ntp permit udp any any eq snmp permit tcp any any eq 22 permit tcp any any eq 23 remark other control plane traffic not configured on router permit eigrp any any permit udp any any eq rip deny ip any any ip access-list extended CoPP_DEFAULT permit ip any any Note: Explicitly defining undesirable traffic with ACL entries enables the network operator to collect statistics. Excessive ARP packets can potentially monopolize Route Processor resources, starving other important processes. Currently, ARP is the only Layer 2 protocol that can be specifically classified using the match protocol command. Step 3: Review the policy-map to determine if the traffic is being policed appropriately for each classification. The following is an example configuration: policy-map CONTROL_PLANE_POLICY class CoPP_CRITICAL police 512000 8000 conform-action transmit exceed-action transmit class CoPP_IMPORTANT police 256000 4000 conform-action transmit exceed-action drop class CoPP_NORMAL police 128000 2000 conform-action transmit exceed-action drop class CoPP_UNDESIRABLE police 8000 1000 conform-action drop exceed-action drop class CoPP_DEFAULT police 64000 1000 conform-action transmit exceed-action drop Step 4: Verify that the CoPP policy is enabled. The following is an example configuration: control-plane service-policy input CONTROL_PLANE_POLICY Note: Control Plane Protection (CPPr) can be used to filter as well as police control plane traffic destined to the RP. CPPr is very similar to CoPP and has the ability to filter and police traffic using finer granularity by dividing the aggregate control plane into three separate categories: (1) host, (2) transit, and (3) CEF-exception. Hence, a separate policy-map could be configured for each traffic category. If the Cisco router is not configured to protect against known types of DoS attacks by employing organization-defined security safeguards, this is a finding. Fix_Text Configure the Cisco router to protect against known types of DoS attacks on the route processor. Implementing a CoPP policy as shown in the example below is a best practice method. Step 1: Configure ACLs specific traffic types. R1(config)#ip access-list extended CoPP_CRITICAL R1(config-ext-nacl)#remark our control plane adjacencies are critical R1(config-ext-nacl)#permit ospf host x.x.x.x any R1(config-ext-nacl)#permit ospf host x.x.x.x any R1(config-ext-nacl)#permit pim host x.x.x.x any R1(config-ext-nacl)#permit pim host x.x.x.x any R1(config-ext-nacl)#permit igmp any 224.0.0.0 15.255.255.255 R1(config-ext-nacl)#permit tcp host x.x.x.x eq bgp host x.x.x.x R1(config-ext-nacl)#deny ip any any R1(config-ext-nacl)#exit R1(config)#ip access-list extended CoPP_IMPORTANT R1(config-ext-nacl)#permit tcp host x.x.x.x eq tacacs any R1(config-ext-nacl)#permit tcp x.x.x.x 0.0.0.255 any eq 22 R1(config-ext-nacl)#permit udp host x.x.x.x any eq snmp R1(config-ext-nacl)#permit udp host x.x.x.x eq ntp any R1(config-ext-nacl)#deny ip any any R1(config-ext-nacl)#exit R1(config)#ip access-list extended CoPP_NORMAL R1(config-ext-nacl)#remark we will want to rate limit ICMP traffic R1(config-ext-nacl)#deny icmp any host x.x.x.x fragments R1(config-ext-nacl)#permit icmp any any echo R1(config-ext-nacl)#permit icmp any any echo-reply R1(config-ext-nacl)#permit icmp any any time-exceeded R1(config-ext-nacl)#permit icmp any any unreachable R1(config-ext-nacl)#deny ip any any R1(config-ext-nacl)#exit R1(config)#ip access-list extended CoPP_UNDESIRABLE R1(config-ext-nacl)#remark management plane traffic that should not be received R1(config-ext-nacl)#permit udp any any eq ntp R1(config-ext-nacl)#permit udp any any eq snmp R1(config-ext-nacl)#permit tcp any any eq 22 R1(config-ext-nacl)#permit tcp any any eq 23 R1(config-ext-nacl)#remark control plane traffic not configured on router R1(config-ext-nacl)#permit eigrp any any R1(config-ext-nacl)#permit udp any any eq rip R1(config-ext-nacl)#deny ip any any R1(config-ext-nacl)#exit R1(config)#ip access-list extended CoPP_DEFAULT R1(config-ext-nacl)#permit ip any any R1(config-ext-nacl)#exit Step 2: Configure class maps referencing each of the ACLs. R1(config)#class-map match-all CoPP_CRITICAL R1(config-cmap)#match access-group name CoPP_CRITICAL R1(config-cmap)#class-map match-any CoPP_IMPORTANT R1(config-cmap)#match access-group name CoPP_IMPORTANT R1(config-cmap)#match protocol arp R1(config-cmap)#class-map match-all CoPP_NORMAL R1(config-cmap)#match access-group name CoPP_NORMAL R1(config-cmap)#class-map match-any CoPP_UNDESIRABLE R1(config-cmap)#match access-group name CoPP_UNDESIRABLE R1(config-cmap)#class-map match-all CoPP_DEFAULT R1(config-cmap)#match access-group name CoPP_DEFAULT R1(config-cmap)#exit Step 3: Configure a policy map referencing the configured class maps and apply appropriate bandwidth allowance and policing attributes. R1(config)#policy-map CONTROL_PLANE_POLICY R1(config-pmap)#class CoPP_CRITICAL R1(config-pmap-c)#police 512000 8000 conform-action transmit exceed-action transmit R1(config-pmap-c-police)#class CoPP_IMPORTANT R1(config-pmap-c)#police 256000 4000 conform-action transmit exceed-action drop R1(config-pmap-c-police)#class CoPP_NORMAL R1(config-pmap-c)#police 128000 2000 conform-action transmit exceed-action drop R1(config-pmap-c-police)#class CoPP_UNDESIRABLE R1(config-pmap-c)#police 8000 1000 conform-action drop exceed-action drop R1(config-pmap-c-police)#class CoPP_DEFAULT R1(config-pmap-c)#police 64000 1000 conform-action transmit exceed-action drop R1(config-pmap-c-police)#exit R1(config-pmap-c)#exit R1(config-pmap)#exit Step 4: Apply the policy map to the control plane. R1(config)#control-plane R1(config-cp)#service-policy input CONTROL_PLANE_POLICY R1(config-cp)#end Not_Reviewed Vuln_Num V-216563 Rule_ID SV-216563r856182_rule Severity medium Rule_Title The Cisco router must be configured to have Gratuitous ARP disabled on all external interfaces. Vuln_Discuss A gratuitous ARP is an ARP broadcast in which the source and destination MAC addresses are the same. It is used to inform the network about a host IP address. A spoofed gratuitous ARP message can cause network mapping information to be stored incorrectly, causing network malfunction. Check_Content Review the configuration to determine if gratuitous ARP is disabled. The following command should not be found in the router configuration: ip gratuitous-arps Note: With Cisco IOS, Gratuitous ARP is enabled and disabled globally. If gratuitous ARP is enabled on any external interface, this is a finding. Fix_Text Disable gratuitous ARP as shown in the example below: R5(config)#no ip gratuitous-arps Not_Reviewed Vuln_Num V-216564 Rule_ID SV-216564r856183_rule Severity low Rule_Title The Cisco router must be configured to have IP directed broadcast disabled on all interfaces. Vuln_Discuss An IP directed broadcast is a datagram sent to the broadcast address of a subnet that is not directly attached to the sending machine. The directed broadcast is routed through the network as a unicast packet until it arrives at the target subnet, where it is converted into a link-layer broadcast. Because of the nature of the IP addressing architecture, only the last router in the chain, which is connected directly to the target subnet, can conclusively identify a directed broadcast. IP directed broadcasts are used in the extremely common and popular smurf, or denial-of-service (DoS), attacks. In a smurf attack, the attacker sends Internet Control Message Protocol (ICMP) echo requests from a falsified source address to a directed broadcast address, causing all the hosts on the target subnet to send replies to the falsified source. By sending a continuous stream of such requests, the attacker can create a much larger stream of replies, which can completely inundate the host whose address is being falsified. This service should be disabled on all interfaces when not needed to prevent smurf and DoS attacks. Directed broadcast can be enabled on internal facing interfaces to support services such as Wake-On-LAN. Case scenario may also include support for legacy applications where the content server and the clients do not support multicast. The content servers send streaming data using UDP broadcast. Used in conjunction with the IP multicast helper-map feature, broadcast data can be sent across a multicast topology. The broadcast streams are converted to multicast and vice versa at the first-hop routers and last-hop routers before entering and leaving the multicast transit area respectively. The last-hop router must convert the multicast to broadcast. Hence, this interface must be configured to forward a broadcast packet (i.e., a directed broadcast address is converted to the all nodes broadcast address). Check_Content Review the router configuration to determine if it is compliant with this requirement. IP directed broadcast command must not be found on any interface as shown in the example below. interface GigabitEthernet0/1 ip address x.x.x.x 255.255.255.0 ip directed-broadcast If IP directed broadcast is not disabled on all interfaces, this is a finding. Fix_Text Disable IP directed broadcast on all interfaces as shown in the example below. R4(config)#int g0/1 R4(config-if)#no ip directed-broadcast Not_Reviewed Vuln_Num V-216565 Rule_ID SV-216565r856184_rule Severity medium Rule_Title The Cisco router must be configured to have Internet Control Message Protocol (ICMP) unreachable messages disabled on all external interfaces. Vuln_Discuss The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Routers automatically send ICMP messages under a wide variety of conditions. Host unreachable ICMP messages are commonly used by attackers for network mapping and diagnosis. Check_Content Review the configuration to verify the no ip unreachables command has been configured on all external interfaces as shown in the configuration example below. interface GigabitEthernet0/1 ip address x.x.x.x 255.255.255.0 no ip unreachables If ICMP unreachable notifications are sent from any external or null0 interface, this is a finding. Alternative – DODIN Backbone Verify that the PE router is configured to rate limit ICMP unreachable messages as shown in the example below. ip icmp rate-limit unreachable 60000 ip icmp rate-limit unreachable DF 1000 Note: In the example above, packet-too-big message (ICMP Type 3 Code 4) can be sent once every second, while all other destination unreachable messages can be sent once every minute. This will avoid disrupting Path MTU Discovery for traffic traversing the backbone while mitigating the risk of an ICMP unreachable DoS attack. If the PE router is not configured to rate limit ICMP unreachable messages, this is a finding. Fix_Text Step 1: Disable ip unreachables on all external interfaces. R4(config)#int g0/1 R4(config-if)#no ip unreachables Step 2: Disable ip unreachables on the Null0 interface if it is used to backhole packets. R4(config-if)#int null 0 R4(config-if)#no ip unreachables Alternative – DODIN Backbone: Configure the PE router to rate limit ICMP unreachable messages as shown in the example below: R4(config)#ip icmp rate-limit unreachable df 100 R4(config)#ip icmp rate-limit unreachable 100000 R4(config)#end Alternative – Non DODIN Backbone. An alternative for non-backbone networks (i.e. enclave, base, camp, etc.) is to filter messages generated by the router and silently drop ICMP Administratively Prohibited and Host Unreachable messages using the following configuration steps: Step 1: Configure ACL to include ICMP Type 3 Code 1 (Host Unreachable) and Code 13 (Administratively Prohibited) as shown in the example below: R2(config)#ip access-list ext ICMP_T3C1C13 R2(config-ext-nacl)#permit icmp any any host-unreachable R2(config-ext-nacl)#permit icmp any any administratively-prohibited R2(config-ext-nacl)#exit Step 2: Create a route map to forward these ICMP messages to the Null0 interface. R2(config)#route-map LOCAL_POLICY R2(config-route-map)#match ip address ICMP_T3C1C13 R2(config-route-map)#set interface Null0 R2(config-route-map)#exit Step 3: Configure no ip unreachables on the Null0 interface. R2(config)#int null 0 R2(config-if)#no ip unreachables R2(config-if)#exit Step 4: Apply the policy to filter messages generated by the router. R2(config)#ip local policy route-map LOCAL_POLICY R2(config)#end Not_Reviewed Vuln_Num V-216566 Rule_ID SV-216566r856185_rule Severity medium Rule_Title The Cisco router must be configured to have Internet Control Message Protocol (ICMP) mask reply messages disabled on all external interfaces. Vuln_Discuss The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Routers automatically send ICMP messages under a wide variety of conditions. Mask Reply ICMP messages are commonly used by attackers for network mapping and diagnosis. Check_Content Review the router configuration and verify that ip mask-reply command is not enabled on any external interfaces as shown in the example below. interface GigabitEthernet0/1 ip address x.x.x.x 255.255.255.0 ip mask-reply If the ip mask-reply command is configured on any external interface, this is a finding. Fix_Text Disable ip mask-reply on all external interfaces as shown below. R4(config)#int g0/1 R4(config-if)#no ip mask-reply Not_Reviewed Vuln_Num V-216567 Rule_ID SV-216567r856186_rule Severity medium Rule_Title The Cisco router must be configured to have Internet Control Message Protocol (ICMP) redirect messages disabled on all external interfaces. Vuln_Discuss The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Routers automatically send ICMP messages under a wide variety of conditions. Redirect ICMP messages are commonly used by attackers for network mapping and diagnosis. Check_Content Review the router configuration to verify that the no ip redirects command has been configured on all external interfaces as shown in the example below. interface GigabitEthernet0/1 ip address x.x.x.x 255.255.255.0 no ip redirects If ICMP Redirect messages are enabled on any external interfaces, this is a finding. Fix_Text Disable ICMP redirects on all external interfaces as shown in the example below. R4(config)#int g0/1 R4(config-if)#no ip redirects Not_Reviewed Vuln_Num V-216568 Rule_ID SV-216568r531085_rule Severity low Rule_Title The Cisco router must be configured to log all packets that have been dropped at interfaces via an ACL. Vuln_Discuss Auditing and logging are key components of any security architecture. It is essential for security personnel to know what is being done or attempted to be done, and by whom, to compile an accurate risk assessment. Auditing the actions on network devices provides a means to recreate an attack or identify a configuration mistake on the device. Check_Content Review all Access Control Lists(ACLs) used to filter traffic and verify that packets being dropped are logged as shown in the configuration below. ip access-list extended INGRESS_FILTER permit tcp any any established permit tcp host x.11.1.1 eq bgp host x.11.1.2 permit tcp host x.11.1.1 host x.11.1.2 eq bgp permit tcp any host x.11.1.5 eq www permit icmp host x.11.1.1 host x.11.1.2 echo permit icmp any any echo-reply … … … deny ip any any log If packets being dropped at interfaces are not logged, this is a finding. Fix_Text Configure ACLs to log packets that are dropped as shown in the example below. R5(config)#ip access-list extended INGRESS_FILTER … … … R5(config-ext-nacl)#deny ip any any log Not_Reviewed Vuln_Num V-216569 Rule_ID SV-216569r531085_rule Severity medium Rule_Title The Cisco router must be configured to produce audit records containing information to establish where the events occurred. Vuln_Discuss Without establishing where events occurred, it is impossible to establish, correlate, and investigate the events leading up to an outage or attack. In order to compile an accurate risk assessment and provide forensic analysis, it is essential for security personnel to know where events occurred, such as router components, modules, device identifiers, node names, and functionality. Associating information about where the event occurred within the network provides a means of investigating an attack, recognizing resource utilization or capacity thresholds, or identifying an improperly configured router. Check_Content Review the router configuration to verify that events are logged containing information to establish where the events occurred as shown in the example below. ip access-list extended INGRESS_FILTER permit tcp any any established permit tcp host x.11.1.1 eq bgp host x.11.1.2 permit tcp host x.11.1.1 host x.11.1.2 eq bgp permit tcp any host x.11.1.5 eq www permit icmp host x.11.1.1 host x.11.1.2 echo permit icmp any any echo-reply … … … deny ip any any log-input Note: When the log-input parameter is configured on deny statements, the log record will contain the interface where ingress packet has been dropped. If the router is not configured to produce audit records containing information to establish to establish where the events occurred, this is a finding. Fix_Text Configure the router to log events containing information to establish where the events occurred as shown in the example below. R5(config)#ip access-list extended INGRESS_FILTER … … … R5(config-ext-nacl)#deny ip any any log-input Not_Reviewed Vuln_Num V-216570 Rule_ID SV-216570r531085_rule Severity medium Rule_Title The Cisco router must be configured to produce audit records containing information to establish the source of the events. Vuln_Discuss Without establishing the source of the event, it is impossible to establish, correlate, and investigate the events leading up to an outage or attack. In order to compile an accurate risk assessment and provide forensic analysis, security personnel need to know the source of the event. In addition to logging where events occur within the network, the audit records must also identify sources of events such as IP addresses, processes, and node or device names. Check_Content Review the router configuration to verify that events are logged containing information to establish the source of the events as shown in the example below. ip access-list extended INGRESS_FILTER permit tcp any any established permit tcp host x.11.1.1 eq bgp host x.11.1.2 permit tcp host x.11.1.1 host x.11.1.2 eq bgp permit tcp any host x.11.1.5 eq www permit icmp host x.11.1.1 host x.11.1.2 echo permit icmp any any echo-reply … … … deny ip any any log-input Note: When the log-input parameter is configured on deny statements, the log record will contain the layer 2 address of the forwarding device for any packet being dropped. If the router is not configured to produce audit records containing information to establish the source of the events, this is a finding. Fix_Text Configure the router to log events containing information to establish where the events occurred as shown in the example below. R5(config)#ip access-list extended INGRESS_FILTER … … … R5(config-ext-nacl)#deny ip any any log-input Not_Reviewed Vuln_Num V-216571 Rule_ID SV-216571r1117237_rule Severity low Rule_Title The Cisco router must be configured to disable the auxiliary port unless it is connected to a secured modem providing encryption and authentication. Vuln_Discuss The use of POTS lines to modems connecting to network devices provides clear text of authentication traffic over commercial circuits that could be captured and used to compromise the network. Additional war dial attacks on the device could degrade the device and the production network. Secured modem devices must be able to authenticate users and must negotiate a key exchange before full encryption takes place. The modem will provide full encryption capability (Triple DES) or stronger. The technician who manages these devices will be authenticated using a key fob and granted access to the appropriate maintenance port; thus, the technician will gain access to the managed device (router, switch, etc.). The token provides a method of strong (two-factor) user authentication. The token works in conjunction with a server to generate one-time user passwords that will change values at second intervals. The user must know a personal identification number (PIN) and possess the token to be allowed access to the device. Check_Content Review the configuration and verify that the auxiliary port is disabled unless a secured modem providing encryption and authentication is connected to it. line aux 0 no exec Note: transport input none is the default, hence it will not be shown in the configuration. If the auxiliary port is not disabled or is not connected to a secured modem when it is enabled, this is a finding. Fix_Text Disable the auxiliary port. R2(config)#line aux 0 R2(config-line)#no exec R2(config-line)#transport input none Not_Reviewed Vuln_Num V-216572 Rule_ID SV-216572r1117241_rule Severity high Rule_Title The Cisco perimeter router must be configured to deny network traffic by default and allow network traffic by exception. Vuln_Discuss A deny-all, permit-by-exception network communications traffic policy ensures that only connections that are essential and approved are allowed. This requirement applies to both inbound and outbound network communications traffic. All inbound and outbound traffic must be denied by default. Firewalls and perimeter routers should only allow traffic through that is explicitly permitted. The initial defense for the internal network is to block any traffic at the perimeter that is attempting to make a connection to a host residing on the internal network. In addition, allowing unknown or undesirable outbound traffic by the firewall or router will establish a state that will permit the return of this undesirable traffic inbound. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to verify that the inbound ACL applied to all external interfaces is configured to allow specific ports and protocols and deny all other traffic. Step 1: Verify that an inbound ACL is applied to all external interfaces as shown in the example below. interface GigabitEthernet0/2 ip address x.11.1.2 255.255.255.254 ip access-group EXTERNAL_ACL in Step 2: Review inbound ACL to verify that it is configured to deny all other traffic that is not explicitly allowed. ip access-list extended EXTERNAL_ACL permit tcp any any established permit tcp host x.11.1.1 eq bgp host x.11.1.2 permit tcp host x.11.1.1 host x.11.1.2 eq bgp permit icmp host x.11.1.1 host x.11.1.2 echo permit icmp host x.11.1.1 host x.11.1.2 echo-reply … … … deny ip any any log-input If the ACL is not configured to allow specific ports and protocols and deny all other traffic, this is a finding. If the ACL is not configured inbound on all external interfaces, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Step 1: Configure an inbound ACL to deny all other traffic by default as shown in the example below. R1(config)#ip access-list extended EXTERNAL_ACL R1(config-ext-nacl)#permit tcp any any established R1(config-ext-nacl)#permit tcp host x.11.1.1 eq bgp host x.11.1.2 R1(config-ext-nacl)#permit tcp host x.11.1.1 host x.11.1.2 eq bgp R1(config-ext-nacl)#permit icmp host x.11.1.1 host x.11.1.2 echo R1(config-ext-nacl)#permit icmp host x.11.1.1 host x.11.1.2 echo-reply … … … R1(config-ext-nacl)#deny ip any any log-input Step 2: Apply the ingress filter to all external interfaces R1(config)#int g0/2 R1(config-if)#ip access-group EXTERNAL_ACL in Not_Reviewed Vuln_Num V-216573 Rule_ID SV-216573r1117237_rule Severity medium Rule_Title The Cisco perimeter router must be configured to enforce approved authorizations for controlling the flow of information between interconnected networks in accordance with applicable policy. Vuln_Discuss Information flow control regulates authorized information to travel within a network and between interconnected networks. Controlling the flow of network traffic is critical so it does not introduce any unacceptable risk to the network infrastructure or data. An example of a flow control restriction is blocking outside traffic claiming to be from within the organization. For most routers, internal information flow control is a product of system design. Check_Content Review the router configuration to verify that ACLs are configured to allow or deny traffic for specific source and destination addresses as well as ports and protocols. In the example below, the router is peering BGP with DISN. ICMP echo and echo-reply packets are allowed for troubleshooting connectivity. WWW traffic is permitted inbound to the NIPRNet host-facing web server (x.12.1.22). interface GigabitEthernet0/1 description Link to DISN ip address x.12.1.10 255.255.255.0 ip access-group FILTER_PERIMETER in … … … ip access-list extended FILTER_PERIMETER permit tcp any any established permit tcp host x.12.1.9 host x.12.1.10 eq bgp permit tcp host x.12.1.9 eq bgp host x.12.1.10 permit icmp host x.12.1.9 host x.12.1.10 echo permit icmp host x.12.1.9 host x.12.1.10 echo-reply permit tcp any host x.12.1.22 eq www deny ip any any log-input If the router is not configured to enforce approved authorizations for controlling the flow of information between interconnected networks, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Step 1: Configure an ACL to allow or deny traffic as shown in the example below. R1(config)#ip access-list extended FILTER_PERIMETER R1(config-ext-nacl)#permit tcp any any established R1(config-ext-nacl)#permit tcp host x.12.1.9 host x.12.1.10 eq bgp R1(config-ext-nacl)#permit tcp host x.12.1.9 eq bgp host x.12.1.10 R1(config-ext-nacl)#permit icmp host x.12.1.9 host x.12.1.10 echo R1(config-ext-nacl)#permit icmp host x.12.1.9 host x.12.1.10 echo-reply R1(config-ext-nacl)#permit tcp any host x.12.1.22 eq www R1(config-ext-nacl)#deny ip any any log-input R1(config-ext-nacl)#exit Step 2: Apply the ACL inbound on all external interfaces. R2(config)#int g0/0 R1(config-if)#ip access-group FILTER_PERIMETER in Not_Reviewed Vuln_Num V-216574 Rule_ID SV-216574r856187_rule Severity medium Rule_Title The Cisco perimeter router must be configured to only allow incoming communications from authorized sources to be routed to authorized destinations. Vuln_Discuss Unrestricted traffic may contain malicious traffic that poses a threat to an enclave or to other connected networks. Additionally, unrestricted traffic may transit a network, which uses bandwidth and other resources. Traffic can be restricted directly by an access control list (ACL), which is a firewall function, or by Policy Routing. Policy Routing is a technique used to make routing decisions based on a number of different criteria other than just the destination network, including source or destination network, source or destination address, source or destination port, protocol, packet size, and packet classification. This overrides the router's normal routing procedures used to control the specific paths of network traffic. It is normally used for traffic engineering but can also be used to meet security requirements; for example, traffic that is not allowed can be routed to the Null0 or discard interface. Policy Routing can also be used to control which prefixes appear in the routing table. This requirement is intended to allow network administrators the flexibility to use whatever technique is most effective. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if the router allows only incoming communications from authorized sources to be routed to authorized destinations. The hypothetical example below allows inbound NTP from server x.1.12.9 only to host x.12.1.21. ip access-list extended FILTER_PERIMETER permit tcp any any established … … … permit udp host x.12.1.9 host x.12.1.21 eq ntp deny ip any any log-input If the router does not restrict incoming communications to allow only authorized sources and destinations, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure the router to allow only incoming communications from authorized sources to be routed to authorized destinations. R1(config)#ip access-list extended FILTER_PERIMETER R1(config-ext-nacl)#nn permit udp host x.12.1.9 host x.12.1.21 eq ntp R1(config-ext-nacl)#end Not_Reviewed Vuln_Num V-216575 Rule_ID SV-216575r863237_rule Severity medium Rule_Title The Cisco perimeter router must be configured to block inbound packets with source Bogon IP address prefixes. Vuln_Discuss Packets with Bogon IP source addresses should never be allowed to traverse the IP core. Bogon IP networks are RFC1918 addresses or address blocks that have never been assigned by the IANA or have been reserved. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to verify that an ingress Access Control List (ACL) applied to all external interfaces is blocking packets with Bogon source addresses. Step 1: Verify an ACL has been configured containing the current Bogon prefixes as shown in the example below. ip access-list extended FILTER_PERIMETER deny ip 0.0.0.0 0.255.255.255 any log-input deny ip 10.0.0.0 0.255.255.255 any log-input deny ip 100.64.0.0 0.63.255.255 any log-input deny ip 127.0.0.0 0.255.255.255 any log-input deny ip 169.254.0.0 0.0.255.255 any log-input deny ip 172.16.0.0 0.15.255.255 any log-input deny ip 192.0.0.0 0.0.0.255 any log-input deny ip 192.0.2.0 0.0.0.255 any log-input deny ip 192.168.0.0 0.0.255.255 any log-input deny ip 198.18.0.0 0.1.255.255 any log-input deny ip 198.51.100.0 0.0.0.255 any log-input deny ip 203.0.113.0 0.0.0.255 any log-input deny ip 224.0.0.0 31.255.255.255 any log-input deny ip 240.0.0.0 15.255.255.255 any log-input permit tcp any any established permit tcp host x.12.1.9 host x.12.1.10 eq bgp permit tcp host x.12.1.9 eq bgp host x.12.1.10 permit icmp host x.12.1.9 host x.12.1.10 echo permit icmp host x.12.1.9 host x.12.1.10 echo-reply … … … deny ip any any log-input Step 2: Verify that the inbound ACL applied to all external interfaces will block all traffic from Bogon source addresses. interface GigabitEthernet0/1 description Link to DISN ip address x.12.1.10 255.255.255.254 ip access-group FILTER_PERIMETER in If the router is not configured to block inbound packets with source Bogon IP address prefixes, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure the perimeter to block inbound packets with Bogon source addresses. Step 1: Configure an ACL containing the current Bogon prefixes as shown below. R5(config)#ip access-list extended FILTER_PERIMETER R5(config-ext-nacl)#deny ip 0.0.0.0 0.255.255.255 any log-input R5(config-ext-nacl)#deny ip 10.0.0.0 0.255.255.255 any log-input R5(config-ext-nacl)#deny ip 100.64.0.0 0.63.255.255 any log-input R5(config-ext-nacl)#deny ip 127.0.0.0 0.255.255.255 any log-input R5(config-ext-nacl)#deny ip 169.254.0.0 0.0.255.255 any log-input R5(config-ext-nacl)#deny ip 172.16.0.0 0.15.255.255 any log-input R5(config-ext-nacl)#deny ip 192.0.0.0 0.0.0.255 any log-input R5(config-ext-nacl)#deny ip 192.0.2.0 0.0.0.255 any log-input R5(config-ext-nacl)#deny ip 192.168.0.0 0.0.255.255 any log-input R5(config-ext-nacl)#deny ip 198.18.0.0 0.1.255.255 any log-input R5(config-ext-nacl)#deny ip 198.51.100.0 0.0.0.255 any log-input R5(config-ext-nacl)#deny ip 203.0.113.0 0.0.0.255 any log-input R5(config-ext-nacl)#deny ip 224.0.0.0 31.255.255.255 any log-input R5(config-ext-nacl)#deny ip 240.0.0.0 15.255.255.255 any log-input R5(config-ext-nacl)#permit tcp any any established R5(config-ext-nacl)#permit tcp host x.12.1.9 host x.12.1.10 eq bgp R5(config-ext-nacl)#permit tcp host x.12.1.9 eq bgp host x.12.1.10 R5(config-ext-nacl)#permit icmp host x.12.1.9 host x.12.1.10 echo R5(config-ext-nacl)#permit icmp host x.12.1.9 host x.12.1.10 echo-reply … … … R5(config-ext-nacl)#deny ip any any log-input R5(config-ext-nacl)#end Step 2: Apply the ACL inbound on all external interfaces. R2(config)#int g0/0 R1(config-if)#ip access-group FILTER_PERIMETER in R1(config-if)#end Not_Reviewed Vuln_Num V-216576 Rule_ID SV-216576r1117237_rule Severity high Rule_Title The Cisco perimeter router must be configured to protect an enclave connected to an approved gateway by using an inbound filter that only permits packets with destination addresses within the sites address space. Vuln_Discuss Enclaves with approved gateway connections must take additional steps to ensure there is no compromise on the enclave network or NIPRNet. Without verifying the destination address of traffic coming from the site's approved gateway, the perimeter router could be routing transit data from the internet into the NIPRNet. This could also make the perimeter router vulnerable to a denial-of-service (DoS) attack and provide a back door into the NIPRNet. The DOD enclave must ensure the ingress filter applied to external interfaces on a perimeter router connecting to an approved gateway is secure through filters permitting packets with a destination address belonging to the DOD enclave's address block. Check_Content This requirement is not applicable for the DODIN backbone. Step 1: Verify the interface connecting to ISP has an inbound ACL as shown in the example below. interface GigabitEthernet0/2 description Link to ISP ip address x.22.1.15 255.255.255.240 ip access-group FILTER_ISP in Step 2: Verify that the ACL only allows traffic to specific destination addresses (i.e., enclave’s NIPRNet address space) as shown in the example below. ip access-list extended FILTER_ISP permit tcp any any established permit icmp host x.12.1.16 host x.12.1.17 echo permit icmp host x.12.1.16 host x.12.1.17 echo-reply permit tcp any host x.12.1.22 eq www permit tcp any host x.12.1.23 eq www permit 50 any host x.12.1.24 permit 51 any host x.12.1.24 deny ip any any log-input Note: An approved gateway is any external connection from a DOD NIPRNet enclave to an internet service provider, network owned by a contractor, or non-DOD federal agency that has been approved by either the DOD CIO or the DOD Component CIO. This approved gateway requirement does not apply to commercial cloud connections when the cloud service provider (CSP) network is connected via the NIPRNet Boundary Cloud Access Point (BCAP). If the ingress ACL bound to the interface connecting to an approved gateway permits packets with addresses other than those specified, such as destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the approved gateway network service provider, this is a finding. Fix_Text This requirement is not applicable for the DODIN backbone. Configure the ingress ACL of the perimeter router connected to an approved gateway to only permit packets with destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the approved gateway network service provider as shown in the example below. R5(config)#ip access-list extended FILTER_ISP R5(config-ext-nacl)#permit tcp any any established R5(config-ext-nacl)#permit icmp host x.12.1.16 host x.12.1.17 echo R5(config-ext-nacl)#permit icmp host x.12.1.16 host x.12.1.17 echo-reply R5(config-ext-nacl)#permit tcp any host x.12.1.22 eq www R5(config-ext-nacl)#permit tcp any host x.12.1.23 eq www R5(config-ext-nacl)#permit 50 any host x.12.1.24 R5(config-ext-nacl)#permit 51 any host x.12.1.24 R5(config-ext-nacl)#deny ip any any log-input R5(config-ext-nacl)#end Not_Reviewed Vuln_Num V-216577 Rule_ID SV-216577r1117237_rule Severity high Rule_Title The Cisco perimeter router must be configured to not be a Border Gateway Protocol (BGP) peer to an approved gateway service provider. Vuln_Discuss ISPs use BGP to share route information with other autonomous systems (i.e., other ISPs and corporate networks). If the perimeter router was configured to BGP peer with an ISP, NIPRNet routes could be advertised to the ISP, thereby creating a backdoor connection from the internet to the NIPRNet. Check_Content This requirement is not applicable for the DODIN backbone. Review the router configuration and verify that it is not BGP peering with an approved gateway service provider. Step 1: Determine the IP address of the ISP router. interface GigabitEthernet0/2 description Link to ISP ip address x.22.1.15 255.255.255.240 Step 2: Verify that the router is not BGP peering with this router. router bgp nn no synchronization bgp log-neighbor-changes neighbor x.11.1.7 remote-as nn neighbor x.11.1.7 password xxxxxxx no auto-summary In the example above, the router is not peering with the ISP. If the router is BGP peering with an approved gateway service provider, this is a finding. Fix_Text This requirement is not applicable for the DODIN backbone. Remove any BGP neighbors belonging to the approved gateway service provider and configure a static route to forward internet-bound traffic to the approved gateway as shown in the example below. R5(config)#ip route 0.0.0.0 0.0.0.0 x.22.1.14 Not_Reviewed Vuln_Num V-216578 Rule_ID SV-216578r1117237_rule Severity low Rule_Title The Cisco perimeter router must be configured to not redistribute static routes to an approved gateway service provider into BGP, an IGP peering with the NIPRNet, or other autonomous systems. Vuln_Discuss If the static routes to the approved gateway are being redistributed into an Exterior Gateway Protocol or Interior Gateway Protocol to a NIPRNet gateway, this could make traffic on NIPRNet flow to that particular router and not to the internet access point routers. This could not only wreak havoc with traffic flows on NIPRNet but could overwhelm the connection from the router to the NIPRNet gateway(s) and cause traffic destined for outside of NIPRNet to bypass the defenses of the internet access points. Check_Content This requirement is not applicable for the DODIN backbone. Step 1: Review the IGP and BGP configurations. If there are redistribute static statements configured as shown in the examples below, proceed to step 2. OSPF Example router ospf 1 log-adjacency-changes redistribute static subnets network 0.0.0.0 255.255.255.255 area 0 EIGRP example router eigrp 1 network 10.1.15.0 0.0.0.255 redistribute static RIP example router rip version 2 redistribute static network 10.0.0.0 BGP example router bgp nn no synchronization bgp log-neighbor-changes redistribute static neighbor x.11.1.7 remote-as nn neighbor x.11.1.7 password xxxxxxx no auto-summary Step 2: Review the static routes that have been configured to determine if any contain the next hop address of the approved gateway. If the static routes to the approved gateway are being redistributed into BGP or any IGP peering to a NIPRNet gateway or any other autonomous system, this is a finding. Fix_Text This requirement is not applicable for the DODIN backbone. Configure the router so that static routes are not redistributed to an approved gateway into either a BGP or any IGP peering with the NIPRNet or to any other autonomous systems. This can be done by excluding that route in the route-map as shown in the example below. Step 1: Configure a prefix list for any static routes with the approved gateway as the next-hop address. R5(config)#ip prefix-list ISP_PREFIX permit x.x.x.0/24 Step 2: Configure a route map that will deny the state routes to the ISP. R5(config)#route-map FILTER_ISP_STATIC deny 10 R5(config-route-map)#match ip address prefix-list ISP_PREFIX R5(config-route-map)#exit R5(config)#route-map FILTER_ISP_STATIC permit 20 R5(config-route-map)#exit Step 3: Apply the route-map to the IGP and BGP redistribute static commands as shown in the EIGRP example. R5(config)#router eigrp 1 R5(config-router)#redistribute static route-map FILTER_ISP_STATIC Not_Reviewed Vuln_Num V-216580 Rule_ID SV-216580r1007822_rule Severity medium Rule_Title The Cisco perimeter router must be configured to filter traffic destined to the enclave in accordance with the guidelines contained in DoD Instruction 8551.1. Vuln_Discuss Vulnerability assessments must be reviewed by the System Administrator, and protocols must be approved by the Information Assurance (IA) staff before entering the enclave. Access control lists (ACLs) are the first line of defense in a layered security approach. They permit authorized packets and deny unauthorized packets based on port or service type. They enhance the posture of the network by not allowing packets to reach a potential target within the security domain. The lists provided are highly susceptible ports and services that should be blocked or limited as much as possible without adversely affecting customer requirements. Auditing packets attempting to penetrate the network but that are stopped by an ACL will allow network administrators to broaden their protective ring and more tightly define the scope of operation. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to verify that the ingress ACL is in accordance with DoD 8551.1. Step 1: Verify that an inbound ACL is configured on all external interfaces. interface GigabitEthernet0/2 ip address x.11.1.2 255.255.255.254 ip access-group EXTERNAL_ACL_INBOUND in Step 2. Review the inbound ACL to verify that it is filtering traffic in accordance with DoD 8551.1. ip access-list extended EXTERNAL_ACL_INBOUND permit tcp any any established permit tcp host x.11.1.1 eq bgp host x.11.1.2 permit tcp host x.11.1.1 host x.11.1.2 eq bgp permit icmp host x.11.1.1 host x.11.1.2 echo permit icmp host x.11.1.1 host x.11.1.2 echo-reply … … < must be in accordance with DoD Instruction 8551.1> … deny ip any any log-input If the router does not filter traffic in accordance with the guidelines contained in DoD 8551.1, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure the router to use an inbound ACL on all external interfaces as shown in the example below to restrict traffic in accordance with the guidelines contained in DOD Instruction 8551.1. R1(config)#ip access-list extended EXTERNAL_ACL_INBOUND R1(config-ext-nacl)#permit tcp any any established R1(config-ext-nacl)#permit tcp host x.11.1.1 eq bgp host x.11.1.2 R1(config-ext-nacl)#permit tcp host x.11.1.1 host x.11.1.2 eq bgp R1(config-ext-nacl)#permit icmp host x.11.1.1 host x.11.1.2 echo R1(config-ext-nacl)#permit icmp host x.11.1.1 host x.11.1.2 echo-reply … … < must be in accordance with DoD Instruction 8551.1> … R1(config-ext-nacl)#deny ip any any log-input R1(config-ext-nacl)#exit R1(config)#int g0/2 R1(config-if)#ip access-group EXTERNAL_ACL_INBOUND in Not_Reviewed Vuln_Num V-216581 Rule_ID SV-216581r531085_rule Severity medium Rule_Title The Cisco perimeter router must be configured to filter ingress traffic at the external interface on an inbound direction. Vuln_Discuss Access lists are used to separate data traffic into that which it will route (permitted packets) and that which it will not route (denied packets). Secure configuration of routers makes use of access lists for restricting access to services on the router itself as well as for filtering traffic passing through the router. Inbound versus Outbound: It should be noted that some operating systems default access lists are applied to the outbound queue. The more secure solution is to apply the access list to the inbound queue for three reasons: - The router can protect itself before damage is inflicted. - The input port is still known and can be filtered upon. - It is more efficient to filter packets before routing them. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to verify that an inbound ACL is configured on all external interfaces as shown in the example below. interface GigabitEthernet0/2 ip address x.11.1.2 255.255.255.254 ip access-group EXTERNAL_ACL_INBOUND in If the router is not configured to filter traffic entering the network at all external interfaces in an inbound direction, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure the router to use an inbound ACL on all external interfaces as shown in the example below. R1(config)#int g0/2 R1(config-if)#ip access-group EXTERNAL_ACL_INBOUND in Not_Reviewed Vuln_Num V-216582 Rule_ID SV-216582r531085_rule Severity medium Rule_Title The Cisco perimeter router must be configured to filter egress traffic at the internal interface on an inbound direction. Vuln_Discuss Access lists are used to separate data traffic into that which it will route (permitted packets) and that which it will not route (denied packets). Secure configuration of routers makes use of access lists for restricting access to services on the router itself as well as for filtering traffic passing through the router. Inbound versus Outbound: It should be noted that some operating systems default access lists are applied to the outbound queue. The more secure solution is to apply the access list to the inbound queue for three reasons: - The router can protect itself before damage is inflicted. - The input port is still known and can be filtered upon. - It is more efficient to filter packets before routing them. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to verify that the egress ACL is bound to the internal interface in an inbound direction. interface interface GigabitEthernet0/2 description downstream link to LAN ip address 10.1.25.5 255.255.255.0 ip access-group EGRESS_FILTER in If the router is not configured to filter traffic leaving the network at the internal interface in an inbound direction, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure the router to use an inbound ACL on all internal interfaces as shown in the example below. R5(config)#int g0/2 R5(config-if)#ip access-group EGRESS_FILTER in Not_Reviewed Vuln_Num V-216584 Rule_ID SV-216584r856189_rule Severity low Rule_Title The Cisco perimeter router must be configured to have Link Layer Discovery Protocol (LLDP) disabled on all external interfaces. Vuln_Discuss LLDP is a neighbor discovery protocol used to advertise device capabilities, configuration information, and device identity. LLDP is media- and protocol-independent as it runs over layer 2; therefore, two network nodes that support different layer 3 protocols can still learn about each other. Allowing LLDP messages to reach external network nodes provides an attacker a method to obtain information of the network infrastructure that can be useful to plan an attack. Check_Content This requirement is not applicable for the DODIN Backbone. Step 1: Verify LLDP is not enabled globally via the command lldp run By default LLDP is not enabled globally. If LLDP is enabled, proceed to step 2. Step 2: Verify LLDP is not enabled on any external interface as shown in the example below. interface GigabitEthernet0/1 ip address x.1.12.1 255.255.255.252 no lldp transmit Note: LLDP is enabled by default on all interfaces once it is enabled globally; hence the command lldp transmit will not be visible on the interface configuration. If LLDP transmit is enabled on any external interface, this is a finding. Fix_Text Disable LLDP transmit on all external interfaces as shown in the example below. R5(config)#int g0/1 R5(config-if)#no lldp transmit Not_Reviewed Vuln_Num V-216585 Rule_ID SV-216585r856190_rule Severity low Rule_Title The Cisco perimeter router must be configured to have Cisco Discovery Protocol (CDP) disabled on all external interfaces. Vuln_Discuss CDP is a Cisco proprietary neighbor discovery protocol used to advertise device capabilities, configuration information, and device identity. CDP is media- and protocol-independent as it runs over layer 2; therefore, two network nodes that support different layer 3 protocols can still learn about each other. Allowing CDP messages to reach external network nodes provides an attacker a method to obtain information of the network infrastructure that can be useful to plan an attack. Check_Content This requirement is not applicable for the DODIN Backbone. Step 1: Verify CDP is not enabled globally via the command no cdp run By default CDP is enabled globally; hence, the command cdp run will not be shown in the configuration. If CDP is enabled, proceed to step 2. Step 2: Verify CDP is not enabled on any external interface as shown in the example below. interface GigabitEthernet0/1 ip address x.1.23.2 255.255.255.252 no cdp enable Note: By default CDP is enabled on all interfaces if CDP is enabled globally. If CDP is enabled on any external interface, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Disable CDP on all external interfaces via no cdp enable command or disable CDP globally via no cdp run command. Not_Reviewed Vuln_Num V-216586 Rule_ID SV-216586r856191_rule Severity medium Rule_Title The Cisco perimeter router must be configured to have Proxy ARP disabled on all external interfaces. Vuln_Discuss When Proxy ARP is enabled on a router, it allows that router to extend the network (at Layer 2) across multiple interfaces (LAN segments). Because proxy ARP allows hosts from different LAN segments to look like they are on the same segment, proxy ARP is only safe when used between trusted LAN segments. Attackers can leverage the trusting nature of proxy ARP by spoofing a trusted host and then intercepting packets. Proxy ARP should always be disabled on router interfaces that do not require it, unless the router is being used as a LAN bridge. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if IP Proxy ARP is disabled on all external interfaces as shown in the example below. interface GigabitEthernet0/1 description link to DISN ip address x.1.12.2 255.255.255.252 no ip proxy-arp Note: By default Proxy ARP is enabled on all interfaces; hence, if enabled, it will not be shown in the configuration. If IP Proxy ARP is enabled on any external interface, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Disable Proxy ARP on all external interfaces as shown in the example below. R2(config)#int g0/1 R2(config-if)#no ip proxy-arp Not_Reviewed Vuln_Num V-216587 Rule_ID SV-216587r945857_rule Severity medium Rule_Title The Cisco perimeter router must be configured to block all outbound management traffic. Vuln_Discuss For in-band management, the management network must have its own subnet in order to enforce control and access boundaries provided by Layer 3 network nodes, such as routers and firewalls. Management traffic between the managed network elements and the management network is routed via the same links and nodes as that used for production or operational traffic. Safeguards must be implemented to ensure that the management traffic does not leak past the perimeter of the managed network. Check_Content This requirement is not applicable for the DODIN Backbone. The perimeter router of the managed network must be configured with an outbound ACL on the egress interface to block all management traffic as shown in the example below. Step 1: Verify that all external interfaces have been configured with an outbound ACL as shown in the example below. interface GigabitEthernet0/2 description link to DISN ip address x.11.1.2 255.255.255.254 ip access-group EXTERNAL_ACL_OUTBOUND out Step 2: Verify that the outbound ACL discards management traffic as shown in the example below. ip access-list extended EXTERNAL_ACL_OUTBOUND deny tcp any any eq tacacs log-input deny tcp any any eq 22 log-input deny udp any any eq snmp log-input deny udp any any eq snmptrap log-input deny udp any any eq syslog log-input permit tcp any any eq www log-input deny ip any any log-input If management traffic is not blocked at the perimeter, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure the perimeter router of the managed network with an outbound ACL on the egress interface to block all management traffic. Step 1: Configure an ACL to block egress management traffic. R5(config)#ip access-list extended EXTERNAL_ACL_OUTBOUND R5(config-ext-nacl)#deny tcp any any eq tacacs log-input R5(config-ext-nacl)#deny tcp any any eq 22 log-input R5(config-ext-nacl)#deny udp any any eq snmp log-input R5(config-ext-nacl)#deny udp any any eq snmptrap log-input R5(config-ext-nacl)#deny udp any any eq syslog log-input R5(config-ext-nacl)#permit tcp any any eq www R5(config-ext-nacl)#deny ip any any log-input R5(config-ext-nacl)#exit Note: Permit commands would be configured to allow applicable outbound traffic. The example above is allowing web traffic. Step 2: Configure the external interfaces with the outbound ACL. R1(config)#int g0/2 R1(config-if)#ip access-group EXTERNAL_ACL_OUTBOUND out Not_Reviewed Vuln_Num V-216588 Rule_ID SV-216588r991838_rule Severity medium Rule_Title The Cisco out-of-band management (OOBM) gateway router must be configured to transport management traffic to the Network Operations Center (NOC) via dedicated circuit, MPLS/VPN service, or IPsec tunnel. Vuln_Discuss Using dedicated paths, the OOBM backbone connects the OOBM gateway routers located at the edge of the managed network and at the NOC. Dedicated links can be deployed using provisioned circuits or MPLS Layer 2 and Layer 3 VPN services or implementing a secured path with gateway-to-gateway IPsec tunnels. The tunnel mode ensures that the management traffic will be logically separated from any other traffic traversing the same path. Check_Content This requirement is not applicable for the DODIN Backbone. Review the network topology diagram to determine connectivity between the managed network and the NOC. Review the OOBM gateway router configuration to validate the path and interface that the management traffic traverses. If an IPsec tunnel is used to transport the management traffic between the NOC and the managed network, review the configuration following the steps below. Step 1: Note the crypto map applied to the external interface. interface interface GigabitEthernet0/2 description link to DISN ip address x.1.24.4 255.255.255.0 crypto map IPSEC_MGMT_MAP Step 2: Review the ISAKMP policy for Phase 1 negotiations and Phase 2 policy for data encryption. crypto isakmp policy 10 authentication pre-share hash sha256 crypto isakmp key xxxxxx address x.1.12.1 ! ! crypto IPsec transform-set TRANS_SET ah-sha256-hmac esp-aes Step 3: Review the crypto map that was bound to the external interface and note the ACL defined that identifies the interesting traffic for the IPsec tunnel. crypto map IPSEC_MGMT_MAP 10 ipsec-isakmp set peer x.1.12.1 set transform-set TRANS_SET match address MGMT_TRAFFIC_ACL Step 4: Review the ACL defined in the crypto map and verify that the destination is the management network. ip access-list extended MGMT_TRAFFIC_ACL permit ip 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 Note: The management network is this example is 10.22.2.0/24 If management traffic is not transported between the managed network and the NOC via dedicated circuit, MPLS/VPN service, or IPsec tunnel, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Ensure that a dedicated circuit, MPLS/VPN service, or IPsec tunnel is deployed to transport management traffic between the managed network and the NOC. If an IPsec tunnel is to be used, the steps below can be used as a guideline. Step 1: Configure the ACL for the management network as the destination. This ACL will be defined in the crypto as the interesting traffic to be forwarded into the IPsec tunnel. R4(config)#ip access-list extended MGMT_TRAFFIC_ACL R4(config-ext-nacl)#permit ip 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 R4(config-ext-nacl)#exit Step 2: Create an ISAKMP policy for Phase 1 negotiations. R4(config)#crypto isakmp policy 10 R4(config-isakmp)#hash sha256 R4(config-isakmp)#authentication pre-share R4(config-isakmp)#exit Step 3: Specify the pre-shared key and the remote peer address. R4(config)#crypto isakmp key 0 xxxxxx address x.1.12.1 Note: Digital certificates can be utilized as an alternative. Step 4: Create the IPSec transform set for the data encryption R4(config)#crypto ipsec transform-set TRANS_SET ah-sha256-hmac esp-aes R4(cfg-crypto-trans)#mode tunnel R4(cfg-crypto-trans)#exit Step 5: Create the crypto map. R4(config)#crypto map IPSEC_MGMT_MAP 10 ipsec-isakmp R4(config-crypto-map)#set peer x.1.12.1 R4(config-crypto-map)#match address MGMT_TRAFFIC_ACL R4(config-crypto-map)#set transform-set TRANS_SET R4(config-crypto-map)#end Step 6: Apply the crypto map to the external interface. R4(config)#int g0/2 R4(config-if)#crypto map IPSEC_MGMT_MAP Not_Reviewed Vuln_Num V-216589 Rule_ID SV-216589r531085_rule Severity medium Rule_Title The Cisco out-of-band management (OOBM) gateway router must be configured to forward only authorized management traffic to the Network Operations Center (NOC). Vuln_Discuss The OOBM network is an IP network used exclusively for the transport of OAM&P data from the network being managed to the OSS components located at the NOC. Its design provides connectivity to each managed network device, enabling network management traffic to flow between the managed network elements and the NOC. This allows the use of paths separate from those used by the managed network. Check_Content This requirement is not applicable for the DODIN Backbone. Review the network topology diagram to determine connectivity between the managed network and the NOC. Review the OOBM gateway router configuration to validate the path that the management traffic traverses. Verify that only management traffic is forwarded through the OOBM interface or IPsec tunnel. If an OOBM link is used, verify that the only authorized management traffic is transported to the NOC by reviewing the outbound ACL applied to the OOBM interface as shown in the example below. Step 1: Note the outbound ACL applied to the OOBM interface. interface GigabitEthernet0/2 description OOB link to NOC ip address 10.11.1.8 255.255.255.0 ip access-group MGMT_TRAFFIC_ACL out Step 2: Review the outbound ACL and verify only management traffic is forwarded to the NOC. ip access-list extended MGMT_TRAFFIC_ACL permit tcp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq tacacs permit tcp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq 22 permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq snmp permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq snmp-trap permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq syslog permit icmp 10.1.34.0 0.0.0.255 10.22.22.0 0.0.0.255 deny ip any any log-input If an IPSec tunnel is used, verify that the only authorized management traffic is transported to the NOC. Step 1: Note the crypto map applied to the external interface. interface interface GigabitEthernet0/2 description link to DISN ip address x.1.24.4 255.255.255.0 crypto map IPSEC_MGMT_MAP Step 2: Review the crypto map that was bound to the external interface and note the ACL defined that identifies the interesting traffic for the IPsec tunnel. crypto map IPSEC_MGMT_MAP 10 ipsec-isakmp set peer x.1.12.1 set transform-set TRANS_SET match address MGMT_TRAFFIC_ACL Step 3: Review the ACL defined in the crypto map and verify only management traffic is forwarded to the NOC. ip access-list extended MGMT_TRAFFIC_ACL permit tcp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq tacacs permit tcp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq 22 permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq snmp permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq snmp-trap permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq syslog permit icmp 10.1.34.0 0.0.0.255 10.22.22.0 0.0.0.255 Note: ICMP is permitted for troubleshooting purposes. The IPSec SA can only identify interesting traffic via address, protocol, and port; hence, the ICMP traffic cannot be qualified via type attribute. If traffic other than authorized management traffic is permitted through the OOBM interface or IPsec tunnel, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure ACLs to permit only authorized management traffic into IPsec tunnels or the OOBM interface used for forwarding management data as shown in the examples below. OOBM Link R4(config)#ip access-list extended MGMT_TRAFFIC_ACL R4(config-ext-nacl)#permit tcp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq tacacs R4(config-ext-nacl)#permit tcp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq 22 R4(config-ext-nacl)#permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq snmp R4(config-ext-nacl)#permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq snmp-trap R4(config-ext-nacl)#permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq syslog R4(config-ext-nacl)#permit icmp 10.1.34.0 0.0.0.255 10.22.22.0 0.0.0.255 echo R4(config-ext-nacl)#permit icmp 10.1.34.0 0.0.0.255 10.22.22.0 0.0.0.255 echo-reply R4(config-ext-nacl)#deny ip any any log-input R4(config-ext-nacl)#exit IPsec Tunnel R4(config)#ip access-list extended MGMT_TRAFFIC_ACL R4(config-ext-nacl)#permit tcp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq tacacs R4(config-ext-nacl#permit tcp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq 22 R4(config-ext-nacl)#permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq snmp R4(config-ext-nacl)#permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq snmp-trap R4(config-ext-nacl)#permit udp 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 eq syslog R4(config-ext-nacl)#permit icmp 10.1.34.0 0.0.0.255 22.22.22.0 0.0.0.255 R4(config-ext-nacl)#exit Not_Reviewed Vuln_Num V-216590 Rule_ID SV-216590r1117237_rule Severity medium Rule_Title The Cisco out-of-band management (OOBM) gateway router must be configured to have separate IGP instances for the managed network and management network. Vuln_Discuss If the gateway router is not a dedicated device for the OOBM network, implementation of several safeguards for containment of management and production traffic boundaries must occur. Since the managed and management network are separate routing domains, configuration of separate Interior Gateway Protocol routing instances is critical on the router to segregate traffic from each network. Check_Content This requirement is not applicable for the DODIN Backbone. Verify that the OOBM interface is an adjacency in the IGP domain for the management network via separate VRF as shown in the example below. router ospf 1 vrf MGMT log-adjacency-changes network 0.0.0.0 255.255.255.255 area 0 ! router ospf 2 vrf PROD log-adjacency-changes network 0.0.0.0 255.255.255.255 area 0 If the router is not configured to have separate IGP instances for the managed network and management network, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure the router to have a separate IGP instance for the management network as shown in the example below. R3(config)#router ospf 1 vrf MGMT R3(config-router)#network 0.0.0.0 0.0.0.0 area 0 R3(config-router)#exit R3(config)#router ospf 2 vrf PROD R3(config-router)#network 0.0.0.0 0.0.0.0 area 0 R3(config-router)#end Not_Reviewed Vuln_Num V-216591 Rule_ID SV-216591r1117237_rule Severity medium Rule_Title The Cisco out-of-band management (OOBM) gateway router must be configured to not redistribute routes between the management network routing domain and the managed network routing domain. Vuln_Discuss If the gateway router is not a dedicated device for the OOBM network, several safeguards must be implemented for containment of management and production traffic boundaries; otherwise, it is possible that management traffic will not be separated from production traffic. Since the managed network and the management network are separate routing domains, separate Interior Gateway Protocol routing instances must be configured on the router, one for the managed network and one for the OOBM network. In addition, the routes from the two domains must not be redistributed to each other. Check_Content This requirement is not applicable for the DODIN Backbone. Verify the Interior Gateway Protocol (IGP) instance used for the managed network does not redistribute routes into the IGP instance used for the management network, and vice versa. The example below imports OSPF routes from the production route table (VRF PROD) into the management route table (VRF MGMT) using BGP. ip vrf MGMT rd 4:4 route-target export 4:4 route-target import 4:4 route-target import 8:8 ! ip vrf PROD rd 8:8 route-target import 8:8 route-target export 8:8 … … … router ospf 1 vrf MGMT log-adjacency-changes redistribute bgp 64512 subnets network 0.0.0.0 255.255.255.255 area 0 ! router ospf 2 vrf PROD log-adjacency-changes network 0.0.0.0 255.255.255.255 area 0 ! router bgp 64512 no synchronization bgp log-neighbor-changes no auto-summary ! address-family ipv4 vrf MGMT no synchronization redistribute ospf 1 vrf MGMT exit-address-family ! address-family ipv4 vrf PROD no synchronization redistribute ospf 2 vrf PROD exit-address-family If the IGP instance used for the managed network redistributes routes into the IGP instance used for the management network, or vice versa, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Remove the configuration that imports routes from the managed network into the management network or vice versa as shown in the example below. R1(config)#ip vrf MGMT R1(config-vrf)#no route-target import 8:8 Not_Reviewed Vuln_Num V-216592 Rule_ID SV-216592r531085_rule Severity medium Rule_Title The Cisco out-of-band management (OOBM) gateway router must be configured to block any traffic destined to itself that is not sourced from the OOBM network or the Network Operations Center (NOC). Vuln_Discuss If the gateway router is not a dedicated device for the OOBM network, several safeguards must be implemented for containment of management and production traffic boundaries. It is imperative that hosts from the managed network are not able to access the OOBM gateway router. Check_Content This requirement is not applicable for the DODIN Backbone. It is only applicable if the OOBM gateway router is not a dedicated device to the OOBM backbone. Verify that traffic destined to itself is only sourced by the OOBM or the NOC. In the example below, the OOBM backbone network is 10.11.1.0/24, the NOC address spaces is 10.12.1.0/24, and the OOBM LAN address space at remote site connecting to the managed network is 10.13.1.0/24. Step 1: Note the inbound ACL applied to the OOBM interfaces. interface GigabitEthernet0/2 description OOB link to NOC ip address 10.11.1.8 255.255.255.0 ip access-group TRAFFIC_FROM_NOC in ! interface GigabitEthernet0/3 description link to OOBM LAN access switch ip address 10.13.1.1 255.255.255.0 ip access-group TRAFFIC_TO_NOC in Step 2: Review the inbound ACL bound to any OOB interface connecting to the OOBM backbone and verify traffic destined to itself is only from the OOBM or NOC address space. ip access-list extended TRAFFIC_FROM_NOC permit ip 10.11.1.0 0.255.255.255 host 10.11.1.8 permit ip 10.12.1.0 0.255.255.255 host 10.11.1.8 permit ip 10.11.1.0 0.255.255.255 host 10.13.1.1 permit ip 10.12.1.0 0.255.255.255 host 10.13.1.1 deny ip any host 10.11.1.8 log-input deny ip any host 10.13.1.1 log-input permit ip 10.11.1.0 0.0.0.255 10.13.1.0 0.0.0.255 permit ip 10.12.1.0 0.0.0.255 10.13.1.0 0.0.0.255 deny ip any any log-input Step 3: Review the inbound ACL bound to any OOBM LAN interfaces and verify traffic destined to itself is from the OOBM LAN address space. ip access-list extended TRAFFIC_TO_NOC permit ip 10.13.1.0 0.255.255.255 host 10.13.1.1 permit ip 10.13.1.0 0.255.255.255 host 10.11.1.8 deny ip any host 10.13.1.1 log-input deny ip any host 10.11.1.8 log-input permit ip 10.13.1.0 0.255.255.255 10.11.1.0 0.0.0.255 permit ip 10.13.1.0 0.255.255.255 10.12.1.0 0.0.0.255 deny ip any any log-input If the router does not block any traffic destined to itself that is not sourced from the OOBM network or the NOC, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. It is only applicable if the OOBM gateway router is not a dedicated device to the OOBM backbone. Step 1: Configure the ACL to only allow traffic to the route processor from the OOBM backbone and the NOC. R4(config)#ip access-list extended TRAFFIC_FROM_NOC R4(config-ext-nacl)#permit ip 10.11.1.0 0.255.255.255 host 10.11.1.8 R4(config-ext-nacl)#permit ip 10.12.1.0 0.255.255.255 host 10.11.1.8 R4(config-ext-nacl)#permit ip 10.11.1.0 0.255.255.255 host 10.13.1.1 R4(config-ext-nacl)#permit ip 10.12.1.0 0.255.255.255 host 10.13.1.1 R4(config-ext-nacl)#deny ip any host 10.11.1.8 log-input R4(config-ext-nacl)#deny ip any host 10.13.1.1 log-input R4(config-ext-nacl)#permit ip 10.11.1.0 0.0.0.255 10.13.1.0 0.0.0.255 R4(config-ext-nacl)#permit ip 10.12.1.0 0.0.0.255 10.13.1.0 0.0.0.255 R4(config-ext-nacl)#deny ip any any log-input Step 2: Configure the ACL to only allow traffic to the route processor from the OOBM LAN. R4(config)#ip access-list extended TRAFFIC_TO_NOC R4(config-ext-nacl)#permit ip 10.13.1.0 0.255.255.255 host 10.13.1.1 R4(config-ext-nacl)#permit ip 10.13.1.0 0.255.255.255 host 10.11.1.8 R4(config-ext-nacl)#deny ip any host 10.13.1.1 log-input R4(config-ext-nacl)#deny ip any host 10.11.1.8 log-input R4(config-ext-nacl)#permit ip 10.13.1.0 0.255.255.255 10.11.1.0 0.0.0.255 R4(config-ext-nacl)#permit ip 10.13.1.0 0.255.255.255 10.12.1.0 0.0.0.255 R4(config-ext-nacl)#deny ip any any log-input R4(config-ext-nacl)#exit Step 3: Apply the ACLs configured above to the appropriate OOBM interfaces as shown in the example below. R4(config)#int g0/2 R4(config-if)#ip access-group TRAFFIC_FROM_NOC in R4(config)#int g0/3 R4(config-if)#ip access-group TRAFFIC_TO_NOC in R4(config-if)#end Not_Reviewed Vuln_Num V-216593 Rule_ID SV-216593r531085_rule Severity medium Rule_Title The Cisco router must be configured to only permit management traffic that ingresses and egresses the out-of-band management (OOBM) interface. Vuln_Discuss The OOBM access switch will connect to the management interface of the managed network elements. The management interface can be a true OOBM interface or a standard interface functioning as the management interface. In either case, the management interface of the managed network element will be directly connected to the OOBM network. An OOBM interface does not forward transit traffic, thereby providing complete separation of production and management traffic. Since all management traffic is immediately forwarded into the management network, it is not exposed to possible tampering. The separation also ensures that congestion or failures in the managed network do not affect the management of the device. If the device does not have an OOBM port, the interface functioning as the management interface must be configured so that management traffic does not leak into the managed network and that production traffic does not leak into the management network. Check_Content This requirement is only applicable where management access to the router is via an OOBM interface which is not a true OOBM interface. Step 1: Verify that the managed interface has an inbound and outbound ACL configured. interface GigabitEthernet0/7 description link to OOBM access switch ip address 10.11.1.22 255.255.255.0 ip access-group INGRESS_MANAGEMENT_ACL in ip access-group EGRESS_MANAGEMENT_ACL out Step 2: Verify that the ingress ACL only allows management and ICMP traffic. ip access-list extended INGRESS_MANAGEMENT_ACL permit tcp any host 10.11.1.22 eq tacacs permit tcp any host 10.11.1.22 eq 22 permit udp any host 10.11.1.22 eq snmp permit udp any host 10.11.1.22 eq snmptrap permit udp any host 10.11.1.22 eq ntp permit icmp any host 10.11.1.22 deny ip any any log-input Step 3: Verify that the egress ACL blocks any transit traffic. ip access-list extended EGRESS_MANAGEMENT_ACL deny ip any any log-input Note: On Cisco routers, local generated packets are not inspected by outgoing interface access-lists. Hence, the above configuration would simply drop any packets not generated by the router; hence, blocking any transit traffic. If the router does not restrict traffic that ingresses and egresses the management interface, this is a finding. Fix_Text If the management interface is not a dedicated OOBM interface, it must be configured with both an ingress and egress ACL. Step 1: Configure an ingress ACL a shown in the example below. R5(config)#ip access-list extended INGRESS_MANAGEMENT_ACL R5(config-ext-nacl)#permit tcp any host 10.11.1.22 eq tacacs R5(config-ext-nacl)#permit tcp any host 10.11.1.22 eq 22 R5(config-ext-nacl)#permit udp any host 10.11.1.22 eq snmp R5(config-ext-nacl)#permit udp any host 10.11.1.22 eq snmptrap R5(config-ext-nacl)#permit udp any host 10.11.1.22 eq ntp R5(config-ext-nacl)#permit icmp any host 10.11.1.22 R5(config-ext-nacl)#deny ip any any log-input R5(config-ext-nacl)#exit Step 2: Configure an egress ACL a shown in the example below. R5(config)#ip access-list extended EGRESS_MANAGEMENT_ACL R5(config-ext-nacl)#deny ip any any log-input R5(config-ext-nacl)#exit Step 3: Apply the ACLs to the OOBM interfaces. R4(config)#int g0/7 R4(config-if)#ip access-group INGRESS_MANAGEMENT_ACL in R4(config-if)#ip access-group EGRESS_MANAGEMENT_ACL out Not_Reviewed Vuln_Num V-216594 Rule_ID SV-216594r531085_rule Severity medium Rule_Title The Cisco router providing connectivity to the Network Operations Center (NOC) must be configured to forward all in-band management traffic via an IPsec tunnel. Vuln_Discuss When the production network is managed in-band, the management network could be housed at a NOC that is located remotely at single or multiple interconnected sites. NOC interconnectivity, as well as connectivity between the NOC and the managed network, must be enabled using IPsec tunnels to provide the separation and integrity of the managed traffic. Check_Content This requirement is not applicable for the DODIN Backbone. Verify that all traffic from the managed network to the management network or NOC and vice-versa is secured via IPsec tunnel. Step 1: Note the crypto map applied to the external interface. interface GigabitEthernet0/2 description link to DISN ip address x.1.24.4 255.255.255.0 crypto map IPSEC_MGMT_MAP Step 2: Review the ISAKMP policy for Phase 1 negotiations and Phase 2 policy for data encryption. crypto isakmp policy 10 authentication pre-share hash sha256 crypto isakmp key xxxxxx address x.1.12.1 ! ! crypto ipsec transform-set TRANS_SET ah-sha256-hmac esp-aes Step 3: Review the crypto map that was bound to the external interface and note the ACL defined that identifies the interesting traffic for the IPsec tunnel. crypto map IPSEC_MGMT_MAP 10 ipsec-isakmp set peer x.1.12.1 set transform-set TRANS_SET match address MGMT_TRAFFIC_ACL Step 4: Review the ACL defined in the crypto map and verify that the destination is the management network. ip access-list extended MGMT_TRAFFIC_ACL permit ip 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 Note: The management network is this example is 10.22.2.0/24 If the management traffic is not secured via IPsec tunnel, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Ensure that all traffic from the managed network to the management network is secured via IPsec tunnel as shown in the configuration examples below. Step 1: Configure the ACL for the management network as the destination. This ACL will be defined in the crypto as the interesting traffic to be forwarded into the IPsec tunnel. R4(config)#ip access-list extended MGMT_TRAFFIC_ACL R4(config-ext-nacl)#permit ip 10.1.34.0 0.0.0.255 10.22.2.0 0.0.0.255 R4(config-ext-nacl)#exit Step 2: Create an ISAKMP policy for Phase 1 negotiations R4(config)#crypto isakmp policy 10 R4(config-isakmp)#hash sha256 R4(config-isakmp)#authentication pre-share R4(config-isakmp)#exit Step 3: Specify the pre-shared key and the remote peer address R4(config)#crypto isakmp key 0 xxxxxx address 10.1.12.1 Note: Digital certificates can be utilized as an alternative. Step 4: Create the Phase 2 policy for the data encryption R4(config)#crypto ipsec transform-set TRANS_SET ah-sha256-hmac esp-aes R4(cfg-crypto-trans)#mode tunnel R4(cfg-crypto-trans)#exit Step 5: Create the crypto map R4(config)#crypto map IPSEC_MGMT_MAP 10 ipsec-isakmp R4(config-crypto-map)#set peer 10.1.12.1 R4(config-crypto-map)#match address MGMT_TRAFFIC_ACL R4(config-crypto-map)#set transform-set TRANS_SET R4(config-crypto-map)#end Step 6: Apply the crypto map to the external interface R4(config)#int g0/2 R4(config-if)#crypto map IPSEC_MGMT_MAP Not_Reviewed Vuln_Num V-216597 Rule_ID SV-216597r1117236_rule Severity medium Rule_Title The Cisco BGP router must be configured to reject inbound route advertisements for any Bogon prefixes. Vuln_Discuss Accepting route advertisements for Bogon prefixes can result in the local autonomous system (AS) becoming a transit for malicious traffic as it will in turn advertise these prefixes to neighbor autonomous systems. Check_Content This check is Not Applicable for JRSS internal EBGP use. Review the router configuration to verify that it will reject BGP routes for any Bogon prefixes. Step 1: Verify a prefix list has been configured containing the current Bogon prefixes as shown in the example below. ip prefix-list PREFIX_FILTER seq 5 deny 0.0.0.0/8 le 32 ip prefix-list PREFIX_FILTER seq 10 deny 10.0.0.0/8 le 32 ip prefix-list PREFIX_FILTER seq 15 deny 100.64.0.0/10 le 32 ip prefix-list PREFIX_FILTER seq 20 deny 127.0.0.0/8 le 32 ip prefix-list PREFIX_FILTER seq 25 deny 169.254.0.0/16 le 32 ip prefix-list PREFIX_FILTER seq 30 deny 172.16.0.0/12 le 32 ip prefix-list PREFIX_FILTER seq 35 deny 192.0.2.0/24 le 32 ip prefix-list PREFIX_FILTER seq 40 deny 192.88.99.0/24 le 32 ip prefix-list PREFIX_FILTER seq 45 deny 192.168.0.0/16 le 32 ip prefix-list PREFIX_FILTER seq 50 deny 198.18.0.0/15 le 32 ip prefix-list PREFIX_FILTER seq 55 deny 198.51.100.0/24 le 32 ip prefix-list PREFIX_FILTER seq 60 deny 203.0.113.0/24 le 32 ip prefix-list PREFIX_FILTER seq 65 deny 224.0.0.0/4 le 32 ip prefix-list PREFIX_FILTER seq 70 deny 240.0.0.0/4 le 32 ip prefix-list PREFIX_FILTER seq 75 permit 0.0.0.0/0 ge 8 Step 2: Verify that the prefix list has been applied to all external BGP peers as shown in the example below. router bgp xx no synchronization bgp log-neighbor-changes neighbor x.1.1.9 remote-as yy neighbor x.1.1.9 prefix-list PREFIX_FILTER in neighbor x.2.1.7 remote-as zz neighbor x.2.1.7 prefix-list PREFIX_FILTER in Route Map Alternative Verify that the route map applied to the external neighbors references the configured Bogon prefix list shown above. router bgp xx no synchronization bgp log-neighbor-changes neighbor x.1.1.9 remote-as yy neighbor x.1.1.9 route-map FILTER_PREFIX_MAP neighbor x.2.1.7 remote-as zz neighbor x.2.1.7 route-map FILTER_PREFIX_MAP … route-map FILTER_PREFIX_MAP permit 10 match ip address prefix-list PREFIX_FILTER If the router is not configured to reject inbound route advertisements for any Bogon prefixes, this is a finding. Fix_Text Configure the router to reject inbound route advertisements for any Bogon prefixes. Step 1: Configure a prefix list containing the current Bogon prefixes as shown below. R1(config)#ip prefix-list PREFIX_FILTER deny 0.0.0.0/8 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 10.0.0.0/8 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 100.64.0.0/10 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 127.0.0.0/8 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 169.254.0.0/16 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 172.16.0.0/12 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 192.0.2.0/24 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 192.88.99.0/24 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 192.168.0.0/16 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 198.18.0.0/15 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 198.51.100.0/24 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 203.0.113.0/24 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 224.0.0.0/4 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 240.0.0.0/4 le 32 R1(config)#ip prefix-list PREFIX_FILTER deny 240.0.0.0/4 le 32 R1(config)#ip prefix-list PREFIX_FILTER permit 0.0.0.0/0 ge 8 Step 2: Apply the prefix list filter inbound to each external BGP neighbor as shown in the example. R1(config)#router bgp xx R1(config-router)#neighbor x.1.1.9 prefix-list PREFIX_FILTER in R1(config-router)#neighbor x.2.1.7 prefix-list PREFIX_FILTER in Route Map Alternative Step 1: Configure the route map referencing the configured prefix list above. R1(config)#route-map FILTER_PREFIX_MAP 10 R1(config-route-map)#match ip address prefix-list PREFIX_FILTER R1(config-route-map)#exit Step 2: Apply the route-map inbound to each external BGP neighbor as shown in the example. R1(config)#router bgp xx R1(config-router)#neighbor x.1.1.9 route-map FILTER_PREFIX_MAP in R1(config-router)#neighbor x.2.1.7 route-map FILTER_PREFIX_MAP in R1(config-router)#end Not_Reviewed Vuln_Num V-216598 Rule_ID SV-216598r1117236_rule Severity medium Rule_Title The Cisco BGP router must be configured to reject inbound route advertisements for any prefixes belonging to the local autonomous system (AS). Vuln_Discuss Accepting route advertisements belonging to the local AS can result in traffic looping or being black holed, or at a minimum using a non-optimized path. Check_Content Review the router configuration to verify that it will reject routes belonging to the local AS. Step 1: Verify a prefix list has been configured containing prefixes belonging to the local AS. In the example below x.13.1.0/24 is the global address space allocated to the local AS. ip prefix-list PREFIX_FILTER seq 5 deny 0.0.0.0/8 le 32 … … … ip prefix-list PREFIX_FILTER seq 74 deny x.13.1.0/24 le 32 ip prefix-list PREFIX_FILTER seq 75 permit 0.0.0.0/0 ge 8 Step 2: Verify that the prefix list has been applied to all external BGP peers as shown in the example below. router bgp xx no synchronization bgp log-neighbor-changes neighbor x.1.1.9 remote-as yy neighbor x.1.1.9 prefix-list PREFIX_FILTER in neighbor x.2.1.7 remote-as zz neighbor x.2.1.7 prefix-list PREFIX_FILTER in If the router is not configured to reject inbound route advertisements belonging to the local AS, this is a finding. Fix_Text Configure the router to reject inbound route advertisements for any prefixes belonging to the local AS. Step 1: Add to the prefix filter list those prefixes belonging to the local autonomous system. R1(config)#ip prefix-list PREFIX_FILTER seq 74 deny x.13.1.0/24 le 32 Step 2: If not already completed to be compliant with previous requirement, apply the prefix list filter inbound to each external BGP neighbor as shown in the example. R1(config)#router bgp xx R1(config-router)#neighbor x.1.1.9 prefix-list PREFIX_FILTER in R1(config-router)#neighbor x.2.1.7 prefix-list PREFIX_FILTER in Not_Reviewed Vuln_Num V-216599 Rule_ID SV-216599r1117236_rule Severity medium Rule_Title The Cisco BGP router must be configured to reject inbound route advertisements from a customer edge (CE) router for prefixes that are not allocated to that customer. Vuln_Discuss As a best practice, a service provider should only accept customer prefixes that have been assigned to that customer and any peering autonomous systems. A multi-homed customer with BGP speaking routers connected to the Internet or other external networks could be breached and used to launch a prefix de-aggregation attack. Without ingress route filtering of customers, the effectiveness of such an attack could impact the entire IP core and its customers. Check_Content Review the router configuration to verify that there are ACLs defined to only accept routes for prefixes that belong to specific customers. Step 1: Verify prefix list has been configured for each customer containing prefixes belonging to each customer as shown in the example below. ip prefix-list PREFIX_FILTER_CUST1 seq 5 permit x.13.1.0/24 le 32 ip prefix-list PREFIX_FILTER_CUST1 seq 10 deny 0.0.0.0/0 ge 8 ip prefix-list PREFIX_FILTER_CUST2 seq 5 permit x.13.2.0/24 le 32 ip prefix-list PREFIX_FILTER_CUST2 seq 10 deny 0.0.0.0/0 ge 8 Step 2: Verify that the prefix lists has been applied to all to the applicable CE peers as shown in the example below. router bgp xx no synchronization bgp log-neighbor-changes neighbor x.12.4.14 remote-as 64514 neighbor x.12.4.14 prefix-list FILTER_PREFIXES_CUST1 in neighbor x.12.4.16 remote-as 64516 neighbor x.12.4.16 prefix-list FILTER_PREFIXES_CUST2 in Note: Routes to PE-CE links within a VPN are needed for troubleshooting end-to-end connectivity across the MPLS/IP backbone. Hence, these prefixes are an exception to this requirement. NOTE: This check is NA for JRSS systems. If the router is not configured to reject inbound route advertisements from each CE router for prefixes that are not allocated to that customer, this is a finding. Fix_Text Configure the router to reject inbound route advertisements from each CE router for prefixes that are not allocated to that customer. Step 1: Configure a prefix list for each customer containing prefixes belonging to each. R1(config)#ip prefix-list PREFIX_FILTER_CUST1 permit x.13.1.0/24 le 32 R1(config)#ip prefix-list PREFIX_FILTER_CUST1 deny 0.0.0.0/0 ge 8 R1(config)#ip prefix-list PREFIX_FILTER_CUST2 permit x.13.2.0/24 le 32 R1(config)#ip prefix-list PREFIX_FILTER_CUST2 deny 0.0.0.0/0 ge 8 Step 2: Apply the prefix list filter inbound to each CE neighbor as shown in the example. R1(config)#router bgp xx R1(config-router)#neighbor x.12.4.14 prefix-list FILTER_PREFIXES_CUST1 in R1(config-router)#neighbor x.12.4.16 prefix-list FILTER_PREFIXES_CUST2 in Not_Reviewed Vuln_Num V-216600 Rule_ID SV-216600r1117236_rule Severity medium Rule_Title The Cisco BGP router must be configured to reject outbound route advertisements for any prefixes that do not belong to any customers or the local autonomous system (AS). Vuln_Discuss Advertisement of routes by an autonomous system for networks that do not belong to any of its customers pulls traffic away from the authorized network. This causes a denial of service (DoS) on the network that allocated the block of addresses and may cause a DoS on the network that is inadvertently advertising it as the originator. It is also possible that a misconfigured or compromised router within the GIG IP core could redistribute IGP routes into BGP, thereby leaking internal routes. Check_Content This requirement is not applicable for the DODIN Backbone. Step 1: Verify that a prefix list has been configured containing prefixes belonging to customers as well as the local AS as shown in the example below. ip prefix-list CE_PREFIX_ADVERTISEMENTS seq 5 permit x.13.1.0/24 le 32 ip prefix-list CE_PREFIX_ADVERTISEMENTS seq 10 permit x.13.2.0/24 le 32 ip prefix-list CE_PREFIX_ADVERTISEMENTS seq 15 permit x.13.3.0/24 le 32 ip prefix-list CE_PREFIX_ADVERTISEMENTS seq 20 permit x.13.4.0/24 le 32 … … … ip prefix-list CE_PREFIX_ADVERTISEMENTS seq 80 deny 0.0.0.0/0 ge 8 Step 2: Verify that the prefix lists has been applied to all CE peers as shown in the example below. router bgp 64512 no synchronization bgp log-neighbor-changes neighbor x.12.4.14 remote-as 64514 neighbor x.12.4.14 prefix-list CE_PREFIX_ADVERTISEMENTS out neighbor x.12.4.16 remote-as 64516 neighbor x.12.4.16 prefix-list CE_PREFIX_ADVERTISEMENTS out If the router is not configured to reject outbound route advertisements that do not belong to any customers or the local AS, this is a finding. Note: This check is NA for JRSS systems. Fix_Text This requirement is not applicable for the DODIN Backbone. Step 1: Configure a prefix list for containing all customer and local AS prefixes as shown in the example below. R1(config)#ip prefix-list CE_PREFIX_ADVERTISEMENTS permit x.13.1.0/24 le 32 R1(config)#ip prefix-list CE_PREFIX_ADVERTISEMENTS permit x.13.2.0/24 le 32 R1(config)#ip prefix-list CE_PREFIX_ADVERTISEMENTS permit x.13.3.0/24 le 32 R1(config)#ip prefix-list CE_PREFIX_ADVERTISEMENTS permit x.13.4.0/24 le 32 … … … R1(config)#ip prefix-list CE_PREFIX_ADVERTISEMENTS deny 0.0.0.0/0 ge 8 Not_Reviewed Vuln_Num V-216601 Rule_ID SV-216601r531085_rule Severity medium Rule_Title The Cisco BGP router must be configured to reject outbound route advertisements for any prefixes belonging to the IP core. Vuln_Discuss Outbound route advertisements belonging to the core can result in traffic either looping or being black holed, or at a minimum, using a non-optimized path. Check_Content Step 1: Verify that a prefix list has been configured containing prefixes belonging to the IP core. ip prefix-list FILTER_CORE_PREFIXES seq 5 deny x.1.1.0/24 le 32 ip prefix-list FILTER _CORE_PREFIXES seq 10 deny x.1.2.0/24 le 32 ip prefix-list FILTER _CORE_PREFIXES seq 15 permit 0.0.0.0/0 ge 8 Step 2: Verify that the prefix lists has been applied to all external BGP peers as shown in the example below. router bgp xx no synchronization bgp log-neighbor-changes neighbor x.1.4.12 remote-as yy neighbor x.1.4.12 prefix-list FILTER _CORE_PREFIXES out If the router is not configured to reject outbound route advertisements for prefixes belonging to the IP core, this is a finding. Fix_Text Step 1: Configure a prefix list for containing all customer and local AS prefixes as shown in the example below. R1(config)#ip prefix-list FILTER_CORE_PREFIXES deny x.1.1.0/24 le 32 R1(config)#ip prefix-list FILTER _CORE_PREFIXES deny x.1.2.0/24 le 32 R1(config)#ip prefix-list FILTER _CORE_PREFIXES permit 0.0.0.0/0 ge 8 Step 2: Apply the prefix list filter outbound to each CE neighbor as shown in the example. R1(config)#router bgp xx R1(config-router)#neighbor x.1.4.12 prefix-list FILTER _CORE_PREFIXES out Not_Reviewed Vuln_Num V-216602 Rule_ID SV-216602r1117236_rule Severity low Rule_Title The Cisco BGP router must be configured to reject route advertisements from BGP peers that do not list their autonomous system (AS) number as the first AS in the AS_PATH attribute. Vuln_Discuss Verifying the path a route has traversed will ensure the IP core is not used as a transit network for unauthorized or possibly even Internet traffic. All autonomous system boundary routers (ASBRs) must ensure updates received from eBGP peers list their AS number as the first AS in the AS_PATH attribute. Check_Content Review the router configuration to verify the router is configured to deny updates received from eBGP peers that do not list their AS number as the first AS in the AS_PATH attribute. By default Cisco IOS enforces the first AS in the AS_PATH attribute for all route advertisements. Review the router configuration to verify that the command no bgp enforce-first-as is not configured. router bgp xx no synchronization no bgp enforce-first-as If the router is not configured to reject updates from peers that do not list their AS number as the first AS in the AS_PATH attribute, this is a finding. Fix_Text Configure the router to deny updates received from eBGP peers that do not list their AS number as the first AS in the AS_PATH attribute. R1(config)#router bgp xx R1(config-router)#bgp enforce-first-as Not_Reviewed Vuln_Num V-216603 Rule_ID SV-216603r1117236_rule Severity low Rule_Title The Cisco BGP router must be configured to reject route advertisements from CE routers with an originating AS in the AS_PATH attribute that does not belong to that customer. Vuln_Discuss Verifying the path a route has traversed will ensure that the local AS is not used as a transit network for unauthorized traffic. To ensure that the local AS does not carry any prefixes that do not belong to any customers, all PE routers must be configured to reject routes with an originating AS other than that belonging to the customer. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to verify the router is configured to deny updates received from CE routers with an originating AS in the AS_PATH attribute that does not belong to that customer. Step 1: Review router configuration and verify that there is an as-path access-list statement defined to only accept routes from a CE router whose AS did not originate the route. The configuration should look similar to the following: ip as-path access-list 10 permit ^yy$ ip as-path access-list 10 deny .* Note: the characters “^” and “$” representing the beginning and the end of the expression respectively are optional and are implicitly defined if omitted. Step 2: Verify that the as-path access-list is referenced by the filter-list inbound for the appropriate BGP neighbors as shown in the example below: router bgp xx neighbor x.1.4.12 remote-as yy neighbor x.1.4.12 filter-list 10 in If the router is not configured to reject updates from CE routers with an originating AS in the AS_PATH attribute that does not belong to that customer, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure the router to reject updates from CE routers with an originating AS in the AS_PATH attribute that does not belong to that customer. Step 1: Configure the as-path ACL as shown in the example below: R1(config)#ip as-path access-list 10 permit ^yy$ R1(config)#ip as-path access-list 10 deny .* Step 2: Apply the as-path filter inbound as shown in the example below: R1(config)#router bgp xx R1(config-router)#neighbor x.1.4.12 filter-list 10 in Not_Reviewed Vuln_Num V-216604 Rule_ID SV-216604r856192_rule Severity medium Rule_Title The Cisco BGP router must be configured to use the maximum prefixes feature to protect against route table flooding and prefix de-aggregation attacks. Vuln_Discuss The effects of prefix de-aggregation can degrade router performance due to the size of routing tables and also result in black-holing legitimate traffic. Initiated by an attacker or a misconfigured router, prefix de-aggregation occurs when the announcement of a large prefix is fragmented into a collection of smaller prefix announcements. In 1997, misconfigured routers in the Florida Internet Exchange network (AS7007) de-aggregated every prefix in their routing table and started advertising the first /24 block of each of these prefixes as their own. Faced with this additional burden, the internal routers became overloaded and crashed repeatedly. This caused prefixes advertised by these routers to disappear from routing tables and reappear when the routers came back online. As the routers came back after crashing, they were flooded with the routing table information by their neighbors. The flood of information would again overwhelm the routers and cause them to crash. This process of route flapping served to destabilize not only the surrounding network but also the entire Internet. Routers trying to reach those addresses would choose the smaller, more specific /24 blocks first. This caused backbone networks throughout North America and Europe to crash. Maximum prefix limits on peer connections combined with aggressive prefix-size filtering of customers' reachability advertisements will effectively mitigate the de-aggregation risk. BGP maximum prefix must be used on all eBGP routers to limit the number of prefixes that it should receive from a particular neighbor, whether customer or peering AS. Consider each neighbor and how many routes they should be advertising and set a threshold slightly higher than the number expected. Check_Content Review the router configuration to verify that the number of received prefixes from each eBGP neighbor is controlled. router bgp xx neighbor x.1.1.9 remote-as yy neighbor x.1.1.9 maximum-prefix nnnnnnn neighbor x.2.1.7 remote-as zz neighbor x.2.1.7 maximum-prefix nnnnnnn If the router is not configured to control the number of prefixes received from each peer to protect against route table flooding and prefix de-aggregation attacks, this is a finding. Fix_Text Configure the router to use the maximum prefixes feature to protect against route table flooding and prefix de-aggregation attacks as shown in the example below. R1(config)#router bgp xx R1(config-router)#neighbor x.1.1.9 maximum-prefix nnnnnnn R1(config-router)#neighbor x.2.1.7 maximum-prefix nnnnnnn Not_Reviewed Vuln_Num V-216605 Rule_ID SV-216605r856193_rule Severity low Rule_Title The Cisco BGP router must be configured to limit the prefix size on any inbound route advertisement to /24 or the least significant prefixes issued to the customer. Vuln_Discuss The effects of prefix de-aggregation can degrade router performance due to the size of routing tables and also result in black-holing legitimate traffic. Initiated by an attacker or a misconfigured router, prefix de-aggregation occurs when the announcement of a large prefix is fragmented into a collection of smaller prefix announcements. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if it is compliant with this requirement. Step 1: Verify that a route filter has been configured to reject prefixes longer than /24, or the least significant prefixes issued to the customers as shown in the example below: ip prefix-list FILTER_PREFIX_LENGTH seq 5 permit 0.0.0.0/0 ge 8 le 24 ip prefix-list FILTER_PREFIX_LENGTH seq 10 deny 0.0.0.0/0 le 32 Step 2: Verify that prefix filtering has been applied to each eBGP peer as shown in the example: router bgp xx neighbor x.1.1.9 remote-as yy neighbor x.1.1.9 prefix-list FILTER_PREFIX_LENGTH in neighbor x.2.1.7 remote-as zz neighbor x.2.1.7 prefix-list FILTER_PREFIX_LENGTH in If the router is not configured to limit the prefix size on any inbound route advertisement to /24, or the least significant prefixes issued to the customer, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure the router to limit the prefix size on any route advertisement to /24 or the least significant prefixes issued to the customer. Step 1: Configure a prefix list to reject any prefix that is longer than /24. R1(config)#ip prefix-list FILTER_PREFIX_LENGTH permit 0.0.0.0/0 ge 8 le 24 R1(config)#ip prefix-list FILTER_PREFIX_LENGTH deny 0.0.0.0/0 le 32 Step 2: Apply the prefix list to all eBGP peers as shown in the example below. R1(config)#router bgp xx R1(config-router)#neighbor x.1.1.9 prefix-list FILTER_PREFIX_LENGTH in R1(config-router)#neighbor x.2.1.7 prefix-list FILTER_PREFIX_LENGTH in Not_Reviewed Vuln_Num V-216606 Rule_ID SV-216606r991839_rule Severity low Rule_Title The Cisco BGP router must be configured to use its loopback address as the source address for iBGP peering sessions. Vuln_Discuss Using a loopback address as the source address offers a multitude of uses for security, access, management, and scalability of the BGP routers. It is easier to construct appropriate ingress filters for router management plane traffic destined to the network management subnet since the source addresses will be from the range used for loopback interfaces instead of a larger range of addresses used for physical interfaces. Log information recorded by authentication and syslog servers will record the router’s loopback address instead of the numerous physical interface addresses. When the loopback address is used as the source for eBGP peering, the BGP session will be harder to hijack since the source address to be used is not known globally, making it more difficult for a hacker to spoof an eBGP neighbor. By using traceroute, a hacker can easily determine the addresses for an eBGP speaker when the IP address of an external interface is used as the source address. The routers within the iBGP domain should also use loopback addresses as the source address when establishing BGP sessions. Check_Content Step 1: Review the router configuration to verify that a loopback address has been configured. interface Loopback0 ip address 10.1.1.1 255.255.255.255 Step 2: Verify that the loopback interface is used as the source address for all iBGP sessions. router bgp xx no synchronization no bgp enforce-first-as bgp log-neighbor-changes redistribute static neighbor 10.1.1.1 remote-as xx neighbor 10.1.1.1 password xxxxxxxx neighbor 10.1.1.1 update-source Loopback0 If the router does not use its loopback address as the source address for all iBGP sessions, this is a finding. Fix_Text Configure the router to use its loopback address as the source address for all iBGP peering. R1(config)#router bgp xx R1(config-router)#neighbor 10.1.1.1 update-source Loopback0 Not_Reviewed Vuln_Num V-216607 Rule_ID SV-216607r991840_rule Severity low Rule_Title The Cisco MPLS router must be configured to use its loopback address as the source address for LDP peering sessions. Vuln_Discuss Using a loopback address as the source address offers a multitude of uses for security, access, management, and scalability of backbone routers. It is easier to construct appropriate ingress filters for router management plane traffic destined to the network management subnet since the source addresses will be from the range used for loopback interfaces instead of from a larger range of addresses used for physical interfaces. Log information recorded by authentication and syslog servers will record the router's loopback address instead of the numerous physical interface addresses. Check_Content Review the router configuration to determine if it is compliant with this requirement. Verify that a loopback address has been configured as shown in the following example: interface Loopback0 ip address 10.1.1.1 255.255.255.255 By default, routers will use its loopback address for LDP peering. If an address has not be configured on the loopback interface, it will use its physical interface connecting to the LDP peer. If the router-id command is specified that overrides this default behavior, verify that it is a loopback interface as shown in the example below. mpls ldp router-id Loopback0 If the router is not configured do use its loopback address for LDP peering, this is a finding. Fix_Text Configure the router to use their loopback address as the source address for LDP peering sessions. As noted in the check content, the default behavior is to use its loopback address. R4(config)#mpls ldp router-id lo0 Not_Reviewed Vuln_Num V-216608 Rule_ID SV-216608r531085_rule Severity low Rule_Title The Cisco MPLS router must be configured to synchronize IGP and LDP to minimize packet loss when an IGP adjacency is established prior to LDP peers completing label exchange. Vuln_Discuss Packet loss can occur when an IGP adjacency is established and the router begins forwarding packets using the new adjacency before the LDP label exchange completes between the peers on that link. Packet loss can also occur if an LDP session closes and the router continues to forward traffic using the link associated with the LDP peer rather than an alternate pathway with a fully synchronized LDP session. The MPLS LDP-IGP Synchronization feature provides a means to synchronize LDP with OSPF or IS-IS to minimize MPLS packet loss. When an IGP adjacency is established on a link but LDP-IGP synchronization is not yet achieved or is lost, the IGP will advertise the max-metric on that link. Check_Content Review the router OSPF or IS-IS configuration and verify that LDP will synchronize with the link-state routing protocol as shown in the example below. OSPF Example router ospf 1 mpls ldp sync IS-IS Example router isis mpls ldp sync net 49.0001.1234.1600.5531.00 If the router is not configured to synchronize IGP and LDP, this is a finding. Fix_Text Configure the MPLS router to synchronize IGP and LDP, minimizing packet loss when an IGP adjacency is established prior to LDP peers completing label exchange. OSPF Example R2(config)#router ospf 1 R2(config-router)#mpls ldp sync IS-IS Example R5(config)#router isis R5(config-router)#mpls ldp sync Not_Reviewed Vuln_Num V-216609 Rule_ID SV-216609r531085_rule Severity low Rule_Title The MPLS router with RSVP-TE enabled must be configured with message pacing to adjust maximum burst and maximum number of RSVP messages to an output queue based on the link speed and input queue size of adjacent core routers. Vuln_Discuss RSVP-TE can be used to perform constraint-based routing when building LSP tunnels within the network core that will support QoS and traffic engineering requirements. RSVP-TE is also used to enable MPLS Fast Reroute, a network restoration mechanism that will reroute traffic onto a backup LSP in case of a node or link failure along the primary path. When there is a disruption in the MPLS core, such as a link flap or router reboot, the result is a significant amount of RSVP signaling, such as "PathErr" and "ResvErr" messages that need to be sent for every LSP using that link. When RSVP messages are sent out, they are sent either hop by hop or with the router alert bit set in the IP header. This means that every router along the path must examine the packet to determine if additional processing is required for these RSVP messages. If there is enough signaling traffic in the network, it is possible for an interface to receive more packets for its input queue than it can hold, resulting in dropped RSVP messages and hence slower RSVP convergence. Increasing the size of the interface input queue can help prevent dropping packets; however, there is still the risk of having a burst of signaling traffic that can fill the queue. Solutions to mitigate this risk are RSVP message pacing or refresh reduction to control the rate at which RSVP messages are sent. RSVP refresh reduction includes the following features: RSVP message bundling, RSVP Message ID to reduce message processing overhead, Reliable delivery of RSVP messages using Message ID, and summary refresh to reduce the amount of information transmitted every refresh interval. Check_Content Review the router configuration to determine RSVP messages are rate limited. Step 1: Determine if MPLS TE is enabled globally and at least one interface as shown in the example below. mpls traffic-eng tunnels … … … interface GigabitEthernet0/2 ip address x.x.x.x 255.255.255.0 mpls traffic-eng tunnels mpls ip Step 2: If MPLS TE is enabled, verify that message pacing is enabled. ip rsvp signaling rate-limit period 30 burst 9 maxsize 2100 limit 50 Note: The command ip rsvp msg-pacing has been deprecated by the command ip rsvp signaling rate-limit. If the router with RSVP-TE enabled does not rate limit RSVP messages based on the link speed and input queue size of adjacent core routers, this is a finding. Fix_Text Configure the router to rate limit RSVP messages per interface as shown in the example. R2(config)#ip rsvp signaling rate-limit burst 9 maxsize 2100 period 30 limit 50 Not_Reviewed Vuln_Num V-216610 Rule_ID SV-216610r531085_rule Severity medium Rule_Title The Cisco MPLS router must be configured to have TTL Propagation disabled. Vuln_Discuss The head end of the label-switched path (LSP), the label edge router (LER) will decrement the IP packet's time-to-live (TTL) value by one and then copy the value to the MPLS TTL field. At each label-switched router (LSR) hop, the MPLS TTL value is decremented by one. The MPLS router that pops the label (either the penultimate LSR or the egress LER) will copy the packet's MPLS TTL value to the IP TTL field and decrement it by one. This TTL propagation is the default behavior. Because the MPLS TTL is propagated from the IP TTL, a traceroute will list every hop in the path, be it routed or label switched, thereby exposing core nodes. With TTL propagation disabled, LER decrements the IP packet's TTL value by one and then places a value of 255 in the packet's MPLS TTL field, which is then decremented by one as the packet passes through each LSR in the MPLS core. Because the MPLS TTL never drops to zero, none of the LSP hops triggers an ICMP TTL exceeded message and consequently, these hops are not recorded in a traceroute. Hence, nodes within the MPLS core cannot be discovered by an attacker. Check_Content Review the router configuration to verify that TTL propagation is disabled as shown in the example below. no mpls ip propagate-ttl If the MPLS router is not configured to disable TTL propagation, this is a finding. Fix_Text Configure the MPLS router to disable TTL propagation as shown in the example below. R5(config)#no mpls ip propagate-ttl Not_Reviewed Vuln_Num V-216611 Rule_ID SV-216611r991841_rule Severity high Rule_Title The Cisco PE router must be configured to have each Virtual Routing and Forwarding (VRF) instance bound to the appropriate physical or logical interfaces to maintain traffic separation between all MPLS L3VPNs. Vuln_Discuss The primary security model for an MPLS L3VPN infrastructure is traffic separation. The service provider must guarantee the customer that traffic from one VPN does not leak into another VPN or into the core, and that core traffic must not leak into any VPN. Hence, it is imperative that each CE-facing interface can only be associated to one VRF—that alone is the fundamental framework for traffic separation. Check_Content Step 1: Review the design plan for deploying MPLS/L3VPN. Step 2: Review all CE-facing interfaces and verify that the proper VRF is defined via the "ip vrf forwarding" command. In the example below, COI1 is bound to interface GigabitEthernet0/1, while COI2 is bound to GigabitEthernet0/2. interface GigabitEthernet0/1 description link to COI1 ip vrf forwarding COI1 ip address x.1.0.1 255.255.255.0 ! interface GigabitEthernet0/2 description link to COI2 ip vrf forwarding COI2 ip address x.2.0.2 255.255.255.0 If any VRFs are not bound to the appropriate physical or logical interface, this is a finding. Fix_Text Configure the PE router to have each VRF bound to the appropriate physical or logical interfaces to maintain traffic separation between all MPLS L3VPNs. Not_Reviewed Vuln_Num V-216612 Rule_ID SV-216612r991842_rule Severity high Rule_Title The Cisco PE router must be configured to have each Virtual Routing and Forwarding (VRF) instance with the appropriate Route Target (RT). Vuln_Discuss The primary security model for an MPLS L3VPN as well as a VRF-lite infrastructure is traffic separation. Each interface can only be associated to one VRF, which is the fundamental framework for traffic separation. Forwarding decisions are made based on the routing table belonging to the VRF. Control of what routes are imported into or exported from a VRF is based on the RT. It is critical that traffic does not leak from one COI tenant or L3VPN to another; hence, it is imperative that the correct RT is configured for each VRF. Check_Content Review the design plan for MPLS/L3VPN to determine what RTs have been assigned for each VRF. Review the router configuration and verify that the correct RT is configured for each VRF. In the example below, route target 13:13 has been configured for customer 1. ip vrf CUST1 rd 13:13 route-target export 13:13 route-target import 13:13 If there are VRFs configured with the wrong RT, this is a finding. Fix_Text Configure the router to have each VRF instance defined with the correct RT. R5(config)#ip vrf CUST1 R5(config-vrf)#route-target import 13:13 R5(config-vrf)#route-target export 13:13 R5(config-vrf)#end Not_Reviewed Vuln_Num V-216613 Rule_ID SV-216613r991844_rule Severity medium Rule_Title The Cisco PE router must be configured to have each VRF with the appropriate Route Distinguisher (RD). Vuln_Discuss An RD provides uniqueness to the customer address spaces within the MPLS L3VPN infrastructure. The concept of the VPN-IPv4 and VPN-IPv6 address families consists of the RD prepended before the IP address. Hence, if the same IP prefix is used in several different L3VPNs, it is possible for BGP to carry several completely different routes for that prefix, one for each VPN. Since VPN-IPv4 addresses and IPv4 addresses are different address families, BGP never treats them as comparable addresses. The purpose of the RD is to create distinct routes for common IPv4 address prefixes. On any given PE router, a single RD can define a VRF in which the entire address space may be used independently, regardless of the makeup of other VPN address spaces. Hence, it is imperative that a unique RD is assigned to each L3VPN and that the proper RD is configured for each VRF. Check_Content Review the design plan for MPLS/L3VPN to determine what RD have been assigned for each VRF. Review the router configuration and verify that the correct RD is configured for each VRF. In the example below, route distinguisher 13:13 has been configured for customer 1. ip vrf CUST1 rd 13:13 Note: This requirement is only applicable for MPLS L3VPN implementations. If the wrong RD has been configured for any VRF, this is a finding. Fix_Text Configure the correct RD for each VRF. R5(config)#ip vrf CUST1 R5(config-vrf)#rd 13:13 R5(config-vrf)#end Not_Reviewed Vuln_Num V-216614 Rule_ID SV-216614r864155_rule Severity medium Rule_Title The Cisco PE router providing MPLS Layer 2 Virtual Private Network (L2VPN) services must be configured to authenticate targeted Label Distribution Protocol (LDP) sessions used to exchange virtual circuit (VC) information using a FIPS-approved message authentication code algorithm. Vuln_Discuss LDP provides the signaling required for setting up and tearing down pseudowires (virtual circuits used to transport Layer 2 frames) across an MPLS IP core network. Using a targeted LDP session, each PE router advertises a virtual circuit label mapping that is used as part of the label stack imposed on the frames by the ingress PE router during packet forwarding. Authentication provides protection against spoofed TCP segments that can be introduced into the LDP sessions. Check_Content The Cisco router is not compliant with this requirement; hence, it is a finding. However, the severity level can be mitigated to a category 3 if the router is configured to authenticate targeted LDP sessions using MD5 as shown in the configuration example below. mpls ldp neighbor 10.1.1.2 password xxxxxxx mpls label protocol ldp If the router is not configured to authenticate targeted LDP sessions using MD5, the finding will remain as a category 2. Fix_Text The severity level can be downgraded to a category 3 if the router is configured to authenticate targeted LDP sessions using MD5 as shown in the example below. R5(config)#mpls ldp neighbor 10.1.1.2 password xxxxxxxx Not_Reviewed Vuln_Num V-216615 Rule_ID SV-216615r991845_rule Severity high Rule_Title The Cisco PE router providing MPLS Virtual Private Wire Service (VPWS) must be configured to have the appropriate virtual circuit identification (VC ID) for each attachment circuit. Vuln_Discuss VPWS is an L2VPN technology that provides a virtual circuit between two PE routers to forward Layer 2 frames between two customer-edge routers or switches through an MPLS-enabled IP core. The ingress PE router (virtual circuit head-end) encapsulates Ethernet frames inside MPLS packets using label stacking and forwards them across the MPLS network to the egress PE router (virtual circuit tail-end). During a virtual circuit setup, the PE routers exchange VC label bindings for the specified VC ID. The VC ID specifies a pseudowire associated with an ingress and egress PE router and the customer-facing attachment circuits. To guarantee that all frames are forwarded onto the correct pseudowire and to the correct customer and attachment circuits, it is imperative that the correct VC ID is configured for each attachment circuit. Check_Content Verify that the correct and unique VCID has been configured for the appropriate attachment circuit. In the example below GigabitEthernet0/1 is the CE-facing interface that is configured for VPWS with the VCID of 55. interface GigabitEthernet0/1 xconnect x.2.2.12 55 encapsulation mpls If the correct VC ID has not been configured on both routers, this is a finding. Fix_Text Assign globally unique VC IDs for each virtual circuit and configure the attachment circuits with the appropriate VC ID. R5(config)#int g0/1 R5(config-if)#xconnect x.2.2.12 55 encapsulation mpls Not_Reviewed Vuln_Num V-216616 Rule_ID SV-216616r531085_rule Severity high Rule_Title The Cisco PE router must be configured to block any traffic that is destined to IP core infrastructure. Vuln_Discuss IP/MPLS networks providing VPN and transit services must provide, at the least, the same level of protection against denial-of-service (DoS) attacks and intrusions as Layer 2 networks. Although the IP core network elements are hidden, security should never rely entirely on obscurity. IP addresses can be guessed. Core network elements must not be accessible from any external host. Protecting the core from any attack is vital for the integrity and privacy of customer traffic as well as the availability of transit services. A compromise of the IP core can result in an outage or, at a minimum, non-optimized forwarding of customer traffic. Protecting the core from an outside attack also prevents attackers from using the core to attack any customer. Hence, it is imperative that all routers at the edge deny traffic destined to any address belonging to the IP core infrastructure. Check_Content Step 1: Review the router configuration to verify that an ingress ACL is applied to all external or CE-facing interfaces. interface GigabitEthernet0/2 ip address x.1.12.2 255.255.255.252 ip access-group BLOCK_TO_CORE in Step 2: Verify that the ingress ACL discards and logs packets destined to the IP core address space. ip access-list extended BLOCK_TO_CORE deny ip any 10.1.x.0 0.0.255.255 log-input permit ip any any ! If the PE router is not configured to block any traffic with a destination address assigned to the IP core infrastructure, this is a finding. Note: Internet Control Message Protocol (ICMP) echo requests and traceroutes will be allowed to the edge from external adjacent neighbors. Fix_Text Configure protection for the IP core to be implemented at the edges by blocking any traffic with a destination address assigned to the IP core infrastructure. Step 1: Configure an ingress ACL to discard and log packets destined to the IP core address space. R2(config)#ip access-list extended BLOCK_TO_CORE R2(config-ext-nacl)#deny ip any 10.1.x.0 0.0.255.255 log-input R2(config-ext-nacl)#exit Step 2: Apply the ACL inbound to all external or CE-facing interfaces. R2(config)#int R4(config)#int g0/2 R2(config-if)#ip access-group BLOCK_TO_CORE in R2(config-if)#end Not_Reviewed Vuln_Num V-216617 Rule_ID SV-216617r531085_rule Severity medium Rule_Title The Cisco PE router must be configured with Unicast Reverse Path Forwarding (uRPF) loose mode enabled on all CE-facing interfaces. Vuln_Discuss The uRPF feature is a defense against spoofing and denial-of-service (DoS) attacks by verifying if the source address of any ingress packet is reachable. To mitigate attacks that rely on forged source addresses, all provider edge routers must enable uRPF loose mode to guarantee that all packets received from a CE router contain source addresses that are in the route table. Check_Content Review the router configuration to determine if uRPF loose mode is enabled on all CE-facing interfaces. interface GigabitEthernet0/2 ip address x.1.12.2 255.255.255.252 ip access-group BLOCK_TO_CORE in ip verify unicast source reachable-via any If uRPF loose mode is not enabled on all CE-facing interfaces, this is a finding. Fix_Text Configure uRPF loose mode on all CE-facing interfaces as shown in the example below. R2(config)#int R4(config)#int g0/2 R2(config-if)#ip verify unicast source reachable-via any R2(config-if)#end Not_Reviewed Vuln_Num V-216619 Rule_ID SV-216619r917417_rule Severity low Rule_Title The Cisco PE router must be configured to enforce a Quality-of-Service (QoS) policy to provide preferred treatment for mission-critical applications. Vuln_Discuss Different applications have unique requirements and toleration levels for delay, jitter, bandwidth, packet loss, and availability. To manage the multitude of applications and services, a network requires a QoS framework to differentiate traffic and provide a method to manage network congestion. The Differentiated Services Model (DiffServ) is based on per-hop behavior by categorizing traffic into different classes and enabling each node to enforce a forwarding treatment to each packet as dictated by a policy. Packet markings such as IP Precedence and its successor, Differentiated Services Code Points (DSCP), were defined along with specific per-hop behaviors for key traffic types to enable a scalable QoS solution. DiffServ QoS categorizes network traffic, prioritizes it according to its relative importance, and provides priority treatment based on the classification. It is imperative that end-to-end QoS is implemented within the IP core network to provide preferred treatment for mission-critical applications. Check_Content Review the router configuration and verify that a QoS policy has been configured to provide preferred treatment for mission-critical applications. Step 1: Verify that the class-maps are configured to match on DSCP values as shown in the configuration example below. class-map match-all C2_VOICE match ip dscp af47 class-map match-all VOICE match ip dscp ef class-map match-all VIDEO match ip dscp af41 class-map match-all CONTROL_PLANE match ip dscp cs6 class-map match-all PREFERRED_DATA match ip dscp af33 Step 2: Verify that the policy map reserves the bandwidth for each traffic type as shown in the following example: policy-map QOS_POLICY class C2_VOICE priority percent 10 class VOICE priority percent 15 class VIDEO bandwidth percent 25 class CONTROL_PLANE priority percent 10 class PREFERRED_DATA bandwidth percent 25 class class-default bandwidth percent 15 Step 3: Verify that an output service policy is bound to all interfaces as shown in the configuration example below. interface GigabitEthernet1/1 ip address 10.1.15.1 255.255.255.252 service-policy output QOS_POLICY ! interface GigabitEthernet1/2 ip address 10.1.15.4 255.255.255.252 service-policy output QOS_POLICY Note: Enclaves must mark or re-mark their traffic to be consistent with the DODIN backbone admission criteria to gain the appropriate level of service. A general DiffServ principle is to mark or trust traffic as close to the source as administratively and technically possible. However, certain traffic types might need to be re-marked before handoff to the DODIN backbone to gain admission to the correct class. If such re-marking is required, it is recommended that the re-marking be performed at the CE egress edge. If the router is not configured to enforce a QoS policy in accordance with the QoS DODIN Technical Profile, this is a finding. Fix_Text Configure to enforce a QoS policy to provide preferred treatment for mission-critical applications. Step 1: Configure class-maps to match on DSCP values as shown in the configuration example below. R5(config-cmap)#class-map match-all C2_VOICE R5(config-cmap)#match ip dscp 47 R5(config-cmap)#class-map match-all VOICE R5(config-cmap)#match ip dscp ef R5(config-cmap)#class-map match-all VIDEO R5(config-cmap)#match ip dscp af41 R5(config-cmap)#class-map match-all CONTROL_PLANE R5(config-cmap)#match ip dscp cs6 R5(config)#class-map match-all PREFERRED_DATA R5(config-cmap)#match ip dscp af33 R5(config-cmap)#exit Step 2: Configure a policy map to be applied to the core-layer-facing interface that reserves the bandwidth for each traffic type as shown in the example below. R5(config)#policy-map QOS_POLICY R5(config-pmap-c)#class C2_VOICE R5(config-pmap-c)#priority percent 10 R5(config-pmap-c)#class VOICE R5(config-pmap-c)#priority percent 15 R5(config-pmap-c)#class VIDEO R5(config-pmap-c)#bandwidth percent 25 R5(config-pmap)#class CONTROL_PLANE R5(config-pmap-c)#priority percent 10 R5(config-pmap-c)#class PREFERRED_DATA R5(config-pmap-c)#bandwidth percent 25 R5(config-pmap-c)#class class-default R5(config-pmap-c)#bandwidth percent 15 R5(config-pmap-c)#exit R5(config-pmap)#exit Step 3: Apply the output service policy to the core-layer-facing interface as shown in the configuration example below. R5(config)#int g1/1 R5(config-if)#service-policy output QOS_POLICY R5(config-if)#exit R5(config)#int g1/2 R5(config-if)#service-policy output QOS_POLICY R5(config-if)#end Not_Reviewed Vuln_Num V-216620 Rule_ID SV-216620r917420_rule Severity low Rule_Title The Cisco P router must be configured to enforce a Quality-of-Service (QoS) policy to provide preferred treatment for mission-critical applications. Vuln_Discuss Different applications have unique requirements and toleration levels for delay, jitter, bandwidth, packet loss, and availability. To manage the multitude of applications and services, a network requires a QoS framework to differentiate traffic and provide a method to manage network congestion. The Differentiated Services Model (DiffServ) is based on per-hop behavior by categorizing traffic into different classes and enabling each node to enforce a forwarding treatment to each packet as dictated by a policy. Packet markings such as IP Precedence and its successor, Differentiated Services Code Points (DSCP), were defined along with specific per-hop behaviors for key traffic types to enable a scalable QoS solution. DiffServ QoS categorizes network traffic, prioritizes it according to its relative importance, and provides priority treatment based on the classification. It is imperative that end-to-end QoS is implemented within the IP core network to provide preferred treatment for mission-critical applications. Check_Content Review the router configuration and verify that a QoS policy has been configured to provide preferred treatment for mission-critical applications. Step 1: Verify that the class-maps are configured to match on DSCP values as shown in the configuration example below. class-map match-all PREFERRED_DATA match ip dscp af33 class-map match-all CONTROL_PLANE match ip dscp cs6 class-map match-all VIDEO match ip dscp af41 class-map match-all VOICE match ip dscp ef class-map match-all C2_VOICE match ip dscp 47 Step 2: Verify that the policy map reserves the bandwidth for each traffic type as shown in the following example: policy-map QOS_POLICY class CONTROL_PLANE priority percent 10 class C2_VOICE priority percent 10 class VOICE priority percent 15 class VIDEO bandwidth percent 25 class PREFERRED_DATA bandwidth percent 25 class class-default bandwidth percent 15 Step 3: Verify that an output service policy is bound to all interfaces as shown in the configuration example below. interface GigabitEthernet1/1 ip address 10.1.15.5 255.255.255.252 service-policy output QOS_POLICY ! interface GigabitEthernet1/2 ip address 10.1.15.8 255.255.255.252 service-policy output QOS_POLICY If the router is not configured to implement a QoS policy in accordance with the QoS DODIN Technical Profile, this is a finding. Fix_Text Configure to enforce a QoS policy to provide preferred treatment for mission-critical applications. Step 1: Configure class-maps to match on DSCP values as shown in the configuration example below. R5(config)#class-map match-all PREFERRED_DATA R5(config-cmap)#match ip dscp af33 R5(config-cmap)#class-map match-all CONTROL_PLANE R5(config-cmap)#match ip dscp cs6 R5(config-cmap)#class-map match-all VIDEO R5(config-cmap)#match ip dscp af41 R5(config-cmap)#class-map match-all VOICE R5(config-cmap)#match ip dscp ef R5(config-cmap)#class-map match-all C2_VOICE R5(config-cmap)#match ip dscp 47 R5(config-cmap)#exit Step 2: Configure a policy map to be applied to the core-layer-facing interface that reserves the bandwidth for each traffic type as shown in the example below. R5(config)#policy-map QOS_POLICY R5(config-pmap)#class CONTROL_PLANE R5(config-pmap-c)#priority percent 10 R5(config-pmap-c)#class C2_VOICE R5(config-pmap-c)#priority percent 10 R5(config-pmap-c)#class VOICE R5(config-pmap-c)#priority percent 15 R5(config-pmap-c)#class VIDEO R5(config-pmap-c)#bandwidth percent 25 R5(config-pmap-c)#class PREFERRED_DATA R5(config-pmap-c)#bandwidth percent 25 R5(config-pmap-c)#class class-default R5(config-pmap-c)#bandwidth percent 15 R5(config-pmap-c)#exit R5(config-pmap)#exit Step 3: Apply the output service policy to all interfaces as shown in the configuration example below. R5(config)#int g1/1 R5(config-if)#service-policy output QOS_POLICY R5(config-if)#exit R5(config)#int g1/2 R5(config-if)#service-policy output QOS_POLICY R5(config-if)#end Not_Reviewed Vuln_Num V-216621 Rule_ID SV-216621r531085_rule Severity medium Rule_Title The Cisco PE router must be configured to enforce a Quality-of-Service (QoS) policy to limit the effects of packet flooding denial-of-service (DoS) attacks. Vuln_Discuss DoS is a condition when a resource is not available for legitimate users. Packet flooding distributed denial-of-service (DDoS) attacks are referred to as volumetric attacks and have the objective of overloading a network or circuit to deny or seriously degrade performance, which denies access to the services that normally traverse the network or circuit. Volumetric attacks have become relatively easy to launch using readily available tools such as Low Orbit Ion Cannon or botnets. Measures to mitigate the effects of a successful volumetric attack must be taken to ensure that sufficient capacity is available for mission-critical traffic. Managing capacity may include, for example, establishing selected network usage priorities or quotas and enforcing them using rate limiting, Quality of Service (QoS), or other resource reservation control methods. These measures may also mitigate the effects of sudden decreases in network capacity that are the result of accidental or intentional physical damage to telecommunications facilities (such as cable cuts or weather-related outages). Check_Content Review the router configuration to determine if it is configured to enforce a QoS policy to limit the effects of packet flooding DoS attacks. Step 1: Verify that a class map has been configured for the Scavenger class as shown in the example below. class-map match-all SCAVENGER match ip dscp cs1 Step 2: Verify that the policy map includes the SCAVENGER class with low priority as shown in the following example below. policy-map QOS_POLICY class CONTROL_PLANE priority percent 10 class C2_VOICE priority percent 10 class VOICE priority percent 15 class VIDEO bandwidth percent 25 class PREFERRED_DATA bandwidth percent 25 class SCAVENGER bandwidth percent 5 class class-default bandwidth percent 10 Note: Traffic out of profile must be marked at the customer access layer or CE egress edge. If the router is not configured to enforce a QoS policy to limit the effects of packet flooding DoS attacks, this is a finding. Fix_Text Step 1: Configure a class map for the SCAVENGER class. R5(config)#class-map match-all SCAVENGER R5(config-cmap)#match ip dscp cs1 Step 2: Add the SCAVENGER class to the policy map as shown in the example below. R5(config)#policy-map QOS_POLICY R5(config-pmap-c)#no class class-default R5(config-pmap)#class SCAVENGER R5(config-pmap-c)#bandwidth percent 5 R5(config-pmap-c)#class class-default R5(config-pmap-c)#bandwidth percent 10 R5(config-pmap-c)#end Not_Reviewed Vuln_Num V-216622 Rule_ID SV-216622r1117237_rule Severity medium Rule_Title The Cisco multicast router must be configured to disable Protocol Independent Multicast (PIM) on all interfaces that are not required to support multicast routing. Vuln_Discuss If multicast traffic is forwarded beyond the intended boundary, it is possible that it can be intercepted by unauthorized or unintended personnel. Limiting where, within the network, a given multicast group's data is permitted to flow is an important first step in improving multicast security. A scope zone is an instance of a connected region of a given scope. Zones of the same scope cannot overlap while zones of a smaller scope will fit completely within a zone of a larger scope. For example, Admin-local scope is smaller than Site-local scope, so the administratively configured boundary fits within the bounds of a site. According to RFC 4007 IPv6 Scoped Address Architecture (section 5), scope zones are also required to be "convex from a routing perspective"; that is, packets routed within a zone must not pass through any links that are outside of the zone. This requirement forces each zone to be one contiguous island rather than a series of separate islands. As stated in the DoD IPv6 IA Guidance for MO3, "One should be able to identify all interfaces of a zone by drawing a closed loop on their network diagram, engulfing some routers and passing through some routers to include only some of their interfaces." Therefore, it is imperative that the network engineers have documented their multicast topology and thereby knows which interfaces are enabled for multicast. Once this is done, the zones can be scoped as required. Check_Content Step 1: Review the network's multicast topology diagram. Step 2: Review the router configuration to verify that only the PIM interfaces as shown in the multicast topology diagram are enabled for PIM as shown in the example below. interface GigabitEthernet1/1 ip address 10.1.3.3 255.255.255.0 ip pim sparse-mode If an interface is not required to support multicast routing and it is enabled, this is a finding. Fix_Text Document all enabled interfaces for PIM in the network's multicast topology diagram. Disable support for PIM on interfaces that are not required to support it. R5(config)#int g1/1 R5(config-if)#no ip pim sparse-mode Not_Reviewed Vuln_Num V-216623 Rule_ID SV-216623r1117237_rule Severity medium Rule_Title The Cisco multicast router must be configured to bind a Protocol Independent Multicast (PIM) neighbor filter to interfaces that have PIM enabled. Vuln_Discuss PIM is a routing protocol used to build multicast distribution trees for forwarding multicast traffic across the network infrastructure. PIM traffic must be limited to only known PIM neighbors by configuring and binding a PIM neighbor filter to those interfaces that have PIM enabled. If a PIM neighbor filter is not applied to those interfaces that have PIM enabled, unauthorized routers can join the PIM domain, discover and use the rendezvous points, and also advertise their rendezvous points into the domain. This can result in a denial of service by traffic flooding or result in the unauthorized transfer of data. Check_Content This requirement is not applicable for the DODIN Backbone. Step 1: Verify all interfaces enabled for PIM have a neighbor ACL bound to the interface as shown in the example below. interface GigabitEthernet1/1 ip address 10.1.2.2 255.255.255.0 ip pim neighbor-filter PIM_NEIGHBORS ip pim sparse-mode Step 2: Review the configured ACL for filtering PIM neighbors as shown in the example below. ip access-list standard PIM_NEIGHBORS permit 10.1.2.6 If PIM neighbor ACLs are not bound to all interfaces that have PIM enabled, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure neighbor ACLs to only accept PIM control plane traffic from documented PIM neighbors. Bind neighbor ACLs to all PIM enabled interfaces. Step 1: Configure ACL for PIM neighbors R2(config)#ip access-list standard PIM_NEIGHBORS R2(config-std-nacl)#permit 10.1.2.6 R2(config-std-nacl)#exit Step 2: Apply the ACL to all interfaces enabled for PIM R2(config)#int g1/1 R2(config-if)#ip pim neighbor-filter PIM_NEIGHBORS Not_Reviewed Vuln_Num V-216624 Rule_ID SV-216624r1117237_rule Severity low Rule_Title The Cisco multicast edge router must be configured to establish boundaries for administratively scoped multicast traffic. Vuln_Discuss If multicast traffic is forwarded beyond the intended boundary, it is possible that it can be intercepted by unauthorized or unintended personnel. Administrative scoped multicast addresses are locally assigned and are to be used exclusively by the enterprise network or enclave. Administrative scoped multicast traffic must not cross the enclave perimeter in either direction. Restricting multicast traffic makes it more difficult for a malicious user to access sensitive traffic. Admin-Local scope is encouraged for any multicast traffic within a network intended for network management, as well as for control plane traffic that must reach beyond link-local destinations. Check_Content Review the router configuration and verify that admin-scope multicast traffic is blocked at the external edge as shown in the example below. interface GigabitEthernet1/2 ip address x.1.12.2 255.255.255.252 ip pim sparse-mode ip multicast boundary MULTICAST_SCOPE … … … ip access-list standard MULTICAST_SCOPE deny 239.0.0.0 0.255.255.255 permit any If the router is not configured to establish boundaries for administratively scoped multicast traffic, this is a finding. Fix_Text Step 1: Configure the ACL to deny packets with multicast administratively scoped destination addresses as shown in the example below. R2(config)#ip access-list standard MULTICAST_SCOPE R2(config-std-nacl)#deny 239.0.0.0 0.255.255.255 R2(config-std-nacl)#permit any R2(config-std-nacl)#exit Step 2: Apply the multicast boundary at the appropriate interfaces as shown in the example below. R2(config)#int g1/2 R2(config-if)#ip multicast boundary MULTICAST_SCOPE R2(config-if)#end Not_Reviewed Vuln_Num V-216625 Rule_ID SV-216625r864156_rule Severity low Rule_Title The Cisco multicast Rendezvous Point (RP) router must be configured to limit the multicast forwarding cache so that its resources are not saturated by managing an overwhelming number of Protocol Independent Multicast (PIM) and Multicast Source Discovery Protocol (MSDP) source-active entries. Vuln_Discuss MSDP peering between networks enables sharing of multicast source information. Enclaves with an existing multicast topology using PIM-SM can configure their RP routers to peer with MSDP routers. As a first step of defense against a denial-of-service (DoS) attack, all RP routers must limit the multicast forwarding cache to ensure that router resources are not saturated managing an overwhelming number of PIM and MSDP source-active entries. Check_Content The Cisco router does not have a mechanism to limit the multicast forwarding cache. However, the risk associated with this requirement can be fully mitigated by configuring the router to: 1. Filter PIM register messages. 2. Rate limiting the number of PIM register messages. 3. Accept MSDP packets only from known MSDP peers. Step 1: Verify that the RP router is configured to filter PIM register messages for any undesirable multicast groups and sources. The example below will deny any multicast streams for groups 239.5.0.0/16 and allow from only sources 10.1.2.6 and 10.1.2.7. ip pim rp-address 10.1.12.3 ip pim accept-register list PIM_REGISTER_FILTER … … … ip access-list extended PIM_REGISTER_FILTER deny ip any 239.5.0.0 0.0.255.255 permit ip host 10.1.2.6 any permit ip host 10.1.2.7 any deny ip any any Step 2: Verify that the router is configured to rate limiting the number of PIM register messages as shown in the example below. ip pim rp-address 10.2.2.2 ip pim register-rate-limit nn Step 3: Review the router configuration to determine if there is a receive path or interface filter to only accept MSDP packets from known MSDP peers as shown in the example below. Step 3a: Verify that interfaces used for MSDP peering have an inbound ACL as shown in the example. interface GigabitEthernet1/1 ip address x.1.28.8 255.255.255.0 ip access-group EXTERNAL_ACL_INBOUND in ip pim sparse-mode Step 3b: Verify that the ACL restricts MSDP peering to only known sources. ip access-list extended EXTERNAL_ACL_INBOUND permit tcp any any established permit tcp host x.1.28.2 host x.1.28.8 eq 639 deny tcp any host x.1.28.8 eq 639 log permit tcp host x.1.28.2 host 10.1.28.8 eq bgp permit tcp host x.1.28.2 eq bgp host x.1.28.8 permit pim host x.1.28.2 pim host x.1.28.8 … … … deny ip any any log Note: MSDP connections is via TCP port 639 If the RP router is not configured to filter PIM register messages, rate limiting the number of PIM register messages, and accept MSDP packets only from known MSDP peers, this is a finding. Fix_Text The risk associated with this requirement can be fully mitigated by configuring the router to filter PIM register messages, rate limiting the number of PIM register messages, and accept MSDP packets only from known MSDP peers. Step 1: Configure the router to filter PIM register messages received from a multicast DR for any undesirable multicast groups and sources. The example below will deny any multicast streams for groups 239.5.0.0/16 and allow from only sources 10.1.2.6 and 10.1.2.7. R2(config)#ip access-list extended PIM_REGISTER_FILTER R2(config-ext-nacl)#deny ip any 239.5.0.0 0.0.255.255 R2(config-ext-nacl)#permit ip host 10.1.2.6 any R2(config-ext-nacl)#permit ip host 10.1.2.7 any R2(config-ext-nacl)#deny ip any any R2(config-ext-nacl)#exit R2(config)#ip pim accept-register list PIM_REGISTER_FILTER R2(config)#end Step 2: Configure the RP to rate limit the number of multicast register messages. R2(config)#ip pim register-rate-limit nn Step 3: Configure the receive path or interface ACLs to only accepts MSDP packets from known MSDP peers. R8(config)#ip access-list extended EXTERNAL_ACL_INBOUND R8(config-ext-nacl)#permit tcp any any established R8(config-ext-nacl)#permit tcp host x.1.28.2 host x.1.28.8 eq 639 R8(config-ext-nacl)#deny tcp any host x.1.28.8 eq 639 R8(config-ext-nacl)#permit tcp host x.1.28.2 host x.1.28.8 eq bgp R8(config-ext-nacl)#permit tcp host x.1.28.2 eq bgp host x.1.28.8 R8(config-ext-nacl)#permit pim host x.1.28.2 host x.1.28.8 … … … R8(config-ext-nacl)#deny ip any any Not_Reviewed Vuln_Num V-216626 Rule_ID SV-216626r1117237_rule Severity low Rule_Title The Cisco multicast Rendezvous Point (RP) router must be configured to filter Protocol Independent Multicast (PIM) Register messages received from the Designated Router (DR) for any undesirable multicast groups and sources. Vuln_Discuss Real-time multicast traffic can entail multiple large flows of data. An attacker can flood a network segment with multicast packets, over-using the available bandwidth and thereby creating a denial-of-service (DoS) condition. Hence, it is imperative that register messages are accepted only for authorized multicast groups and sources. Check_Content Verify that the RP router is configured to filter PIM register messages. The example below will deny any multicast streams for groups 239.5.0.0/16 and allow from only sources 10.1.2.6 and 10.1.2.7. ip pim rp-address 10.1.12.3 ip pim accept-register list PIM_REGISTER_FILTER … … … ip access-list extended PIM_REGISTER_FILTER deny ip any 239.5.0.0 0.0.255.255 permit ip host 10.1.2.6 any permit ip host 10.1.2.7 any deny ip any any If the RP router peering with PIM-SM routers is not configured with a policy to block registration messages for any undesirable multicast groups and sources, this is a finding. Fix_Text Configure the router to filter PIM register messages received from a multicast DR for any undesirable multicast groups and sources. The example below will deny any multicast streams for groups 239.5.0.0/16 and allow from only sources 10.1.2.6 and 10.1.2.7. R2(config)#ip access-list extended PIM_REGISTER_FILTER R2(config-ext-nacl)#deny ip any 239.5.0.0 0.0.255.255 R2(config-ext-nacl)#permit ip host 10.1.2.6 any R2(config-ext-nacl)#permit ip host 10.1.2.7 any R2(config-ext-nacl)#deny ip any any R2(config-ext-nacl)#exit R2(config)#ip pim accept-register list PIM_REGISTER_FILTER R2(config)#end Not_Reviewed Vuln_Num V-216627 Rule_ID SV-216627r1117237_rule Severity low Rule_Title The Cisco multicast Rendezvous Point (RP) router must be configured to filter Protocol Independent Multicast (PIM) Join messages received from the Designated Router (DR) for any undesirable multicast groups. Vuln_Discuss Real-time multicast traffic can entail multiple large flows of data. An attacker can flood a network segment with multicast packets, over-using the available bandwidth and thereby creating a denial-of-service (DoS) condition. Hence, it is imperative that join messages are only accepted for authorized multicast groups. Check_Content Verify that the RP router is configured to filter PIM join messages for any undesirable multicast groups. In the example below, groups from 239.8.0.0/16 are not allowed. ip pim rp-address 10.2.2.2 ip pim accept-rp 10.2.2.2 FILTER_PIM_JOINS … … … ip access-list standard FILTER_PIM_JOINS deny 239.8.0.0 0.0.255.255 permit any ! If the RP is not configured to filter join messages received from the DR for any undesirable multicast groups, this is a finding. Fix_Text Configure the RP to filter PIM join messages for any undesirable multicast groups as shown in the example below. R2(config)#ip access-list standard PIM_JOIN_FILTER R2(config-std-nacl)#deny 239.8.0.0 0.0.255.255 R2(config-std-nacl)#permit any R2(config-std-nacl)#exit R2(config)#ip pim accept-rp 10.2.2.2 PIM_JOIN_FILTER R2(config)#end Not_Reviewed Vuln_Num V-216628 Rule_ID SV-216628r856196_rule Severity medium Rule_Title The Cisco multicast Rendezvous Point (RP) must be configured to rate limit the number of Protocol Independent Multicast (PIM) Register messages. Vuln_Discuss When a new source starts transmitting in a PIM Sparse Mode network, the DR will encapsulate the multicast packets into register messages and forward them to the RP using unicast. This process can be taxing on the CPU for both the DR and the RP if the source is running at a high data rate and there are many new sources starting at the same time. This scenario can potentially occur immediately after a network failover. The rate limit for the number of register messages should be set to a relatively low value based on the known number of multicast sources within the multicast domain. Check_Content Review the configuration of the RP to verify that it is rate limiting the number of PIM register messages. ip pim rp-address 10.2.2.2 ip pim register-rate-limit nn If the RP is not limiting PIM register messages, this is a finding. Fix_Text Configure the RP to rate limit the number of multicast register messages. R2(config)#ip pim register-rate-limit nn Not_Reviewed Vuln_Num V-216629 Rule_ID SV-216629r864157_rule Severity low Rule_Title The Cisco multicast Designated Router (DR) must be configured to filter the Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Report messages to allow hosts to join only multicast groups that have been approved by the organization. Vuln_Discuss Real-time multicast traffic can entail multiple large flows of data. Large unicast flows tend to be fairly isolated (i.e., someone doing a file download here or there), whereas multicast can have broader impact on bandwidth consumption, resulting in extreme network congestion. Hence, it is imperative that there is multicast admission control to restrict which multicast groups hosts are allowed to join via IGMP or MLD. Check_Content Review the configuration of the DR to verify that it is filtering IGMP or MLD Membership Report messages, allowing hosts to join only those groups that have been approved. Step 1: Verify that all host facing interfaces are configured to filter IGMP Membership Report messages (IGMP joins) as shown in the example below. interface GigabitEthernet0/0 ip address 10.3.3.3 255.255.255.0 ip pim sparse-mode ip igmp access-group IGMP_JOIN_FILTER ip igmp version 3 Step 2: Verify that the Access Control List (ACL) denies unauthorized groups or permits only authorized groups. The example below denies all groups from 239.8.0.0/16 range. ip access-list standard IGMP_JOIN_FILTER deny 239.8.0.0 0.0.255.255 permit any Note: This requirement is only applicable to Source Specific Multicast (SSM) implementation. This requirement is not applicable to Any Source Multicast (ASM) since the filtering is being performed by the Rendezvous Point router. If the DR is not filtering IGMP or MLD Membership Report messages, this is a finding. Fix_Text Configure the DR to filter the IGMP or MLD Membership Report messages to allow hosts to join only those multicast groups that have been approved. Step 1: Configure the ACL to filter IGMP Membership Report messages as shown in the example. R3(config)#ip access-list standard IGMP_JOIN_FILTER R3(config-std-nacl)#deny 239.8.0.0 0.0.255.255 R3(config-std-nacl)#permit any R3(config-std-nacl)#exit Step 2: Apply the filter to all host facing interfaces. R3(config)#int g0/0 R3(config-if)#ip igmp access-group IGMP_JOIN_FILTER Not_Reviewed Vuln_Num V-216630 Rule_ID SV-216630r864158_rule Severity medium Rule_Title The Cisco multicast Designated Router (DR) must be configured to filter the Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Report messages to allow hosts to join a multicast group only from sources that have been approved by the organization. Vuln_Discuss Real-time multicast traffic can entail multiple large flows of data. Large unicast flows tend to be fairly isolated (i.e., someone doing a file download here or there), whereas multicast can have broader impact on bandwidth consumption, resulting in extreme network congestion. Hence, it is imperative that there is multicast admission control to restrict which multicast groups hosts are allowed to join via IGMP or MLD. Check_Content Review the configuration of the DR to verify that it is filtering IGMP or MLD report messages, allowing hosts to only join multicast groups from sources that have been approved. Step 1: Verify that all host-facing interfaces are configured to filter IGMP Membership Report messages (IGMP joins) as shown in the example below. interface GigabitEthernet0/0 ip address 10.3.3.3 255.255.255.0 ip pim sparse-mode ip igmp access-group IGMP_JOIN_FILTER ip igmp version 3 Step 2: Verify that the Access Control List (ACL) denies unauthorized sources or allows only authorized sources. The example below denies all groups from 232.8.0.0/16 range and permits sources only from the x.0.0.0/8 network. ip access-list extended IGMP_JOIN_FILTER deny ip any 232.8.0.0 0.0.255.255 permit ip x.0.0.0 0.255.255.255 any deny ip any any Note: This requirement is only applicable to Source Specific Multicast (SSM) implementation. If the DR is not filtering IGMP or MLD report messages, this is a finding. Fix_Text Configure the DR to filter the IGMP and MLD report messages to allow hosts to join only those multicast groups from sources that have been approved as shown in the example. R3(config)#ip access-list extended IGMP_JOIN_FILTER R3(config-ext-nacl)#deny ip any 232.8.0.0 0.0.255.255 R3(config-ext-nacl)#permit ip x.0.0.0 0.255.255.255 any R3(config-ext-nacl)#deny ip any any R3(config-ext-nacl)#exit Step 2: Apply the filter to all host facing interfaces. R3(config)#int g0/0 R3(config-if)#ip igmp access-group IGMP_JOIN_FILTER Not_Reviewed Vuln_Num V-216631 Rule_ID SV-216631r856199_rule Severity medium Rule_Title The Cisco multicast Designated Router (DR) must be configured to limit the number of mroute states resulting from Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Host Membership Reports. Vuln_Discuss The current multicast paradigm can let any host join any multicast group at any time by sending an IGMP or MLD membership report to the DR. In a Protocol Independent Multicast (PIM) Sparse Mode network, the DR will send a PIM Join message for the group to the RP. Without any form of admission control, this can pose a security risk to the entire multicast domain - specifically the multicast routers along the shared tree from the DR to the RP that must maintain the mroute state information for each group join request. Hence, it is imperative that the DR is configured to limit the number of mroute state information that must be maintained to mitigate the risk of IGMP or MLD flooding. Check_Content Review the DR configuration to verify that it is limiting the number of mroute states via IGMP or MLD. Verify IGMP limits have been configured globally or on each host-facing interface via the ip igmp limit command as shown in the example. interface GigabitEthernet0/0 ip address 10.3.3.3 255.255.255.0 … … … ip igmp limit nn If the DR is not limiting multicast join requests via IGMP or MLD on a global or interfaces basis, this is a finding. Fix_Text Configure the DR on a global or interface basis to limit the number of mroute states resulting from IGMP or MLD membership reports. R3(config)#int g0/0 R3(config-if)#ip igmp limit 2 Not_Reviewed Vuln_Num V-216632 Rule_ID SV-216632r945856_rule Severity medium Rule_Title The Cisco multicast Designated Router (DR) must be configured to set the shortest-path tree (SPT) threshold to infinity to minimalize source-group (S, G) state within the multicast topology where Any Source Multicast (ASM) is deployed. Vuln_Discuss ASM can have many sources for the same groups (many-to-many). For many receivers, the path via the RP may not be ideal compared with the shortest path from the source to the receiver. By default, the last-hop router will initiate a switch from the shared tree to a source-specific SPT to obtain lower latencies. This is accomplished by the last-hop router sending an (S, G) Protocol Independent Multicast (PIM) Join toward S (the source). When the last-hop router begins to receive traffic for the group from the source via the SPT, it will send a PIM Prune message to the RP for the (S, G). The RP will then send a Prune message toward the source. The SPT switchover becomes a scaling issue for large multicast topologies that have many receivers and many sources for many groups because (S, G) entries require more memory than (*, G). Hence, it is imperative to minimize the amount of (S, G) state to be maintained by increasing the threshold that determines when the SPT switchover occurs. Check_Content Review the DR configuration to verify that the SPT switchover threshold is increased (default is "0") or set to infinity (never switch over). ip pim rp-address 10.2.2.2 ip pim spt-threshold infinity If the DR is not configured to increase the SPT threshold or set to infinity to minimalize (S, G) state, this is a finding. Fix_Text Configure the DR to increase the SPT threshold or set it to infinity to minimalize (S, G) state within the multicast topology where ASM is deployed. R3(config)#ip pim spt-threshold infinity Not_Reviewed Vuln_Num V-216633 Rule_ID SV-216633r856201_rule Severity medium Rule_Title The Cisco Multicast Source Discovery Protocol (MSDP) router must be configured to only accept MSDP packets from known MSDP peers. Vuln_Discuss MSDP peering with customer network routers presents additional risks to the DISN Core, whether from a rogue or misconfigured MSDP-enabled router. To guard against an attack from malicious MSDP traffic, the receive path or interface filter for all MSDP-enabled RP routers must be configured to only accept MSDP packets from known MSDP peers. Check_Content Review the router configuration to determine if there is a receive path or interface filter to only accept MSDP packets from known MSDP peers. Step 1: Verify that interfaces used for MSDP peering have an inbound ACL as shown in the example. interface GigabitEthernet1/1 ip address x.1.28.8 255.255.255.0 ip access-group EXTERNAL_ACL_INBOUND in ip pim sparse-mode Step 2: Verify that the ACL restricts MSDP peering to only known sources. ip access-list extended EXTERNAL_ACL_INBOUND permit tcp any any established permit tcp host x.1.28.2 host x.1.28.8 eq 639 deny tcp any host x.1.28.8 eq 639 log permit tcp host x.1.28.2 host 10.1.28.8 eq bgp permit tcp host x.1.28.2 eq bgp host x.1.28.8 permit pim host x.1.28.2 pim host x.1.28.8 … … … deny ip any any log Note: MSDP connections is via TCP port 639 If the router is not configured to only accept MSDP packets from known MSDP peers, this is a finding. Fix_Text Configure the receive path or interface ACLs to only accept MSDP packets from known MSDP peers. R8(config)#ip access-list extended EXTERNAL_ACL_INBOUND R8(config-ext-nacl)#permit tcp any any established R8(config-ext-nacl)#permit tcp host x.1.28.2 host x.1.28.8 eq 639 R8(config-ext-nacl)#deny tcp any host x1.28.8 eq 639 R8(config-ext-nacl)#permit tcp host x.1.28.2 host x.1.28.8 eq bgp R8(config-ext-nacl)#permit tcp host x.1.28.2 eq bgp host x.1.28.8 R8(config-ext-nacl)#permit pim host x.1.28.2 host x.1.28.8 … … … R8(config-ext-nacl)#deny ip any any Not_Reviewed Vuln_Num V-216634 Rule_ID SV-216634r856202_rule Severity medium Rule_Title The Cisco Multicast Source Discovery Protocol (MSDP) router must be configured to authenticate all received MSDP packets. Vuln_Discuss MSDP peering with customer network routers presents additional risks to the core, whether from a rogue or misconfigured MSDP-enabled router. MSDP password authentication is used to validate each segment sent on the TCP connection between MSDP peers, protecting the MSDP session against the threat of spoofed packets being injected into the TCP connection stream. Check_Content Review the router configuration to determine if received MSDP packets are authenticated. ip msdp peer x.1.28.8 remote-as 8 ip msdp password peer x.1.28.8 xxxxxxxxxxxx If the router does not require MSDP authentication, this is a finding. Fix_Text Configure the router to authenticate MSDP messages as shown in the following example: R2(config)#ip msdp password peer x.1.28.8 xxxxxxxxxxxx Not_Reviewed Vuln_Num V-216635 Rule_ID SV-216635r1117236_rule Severity low Rule_Title The Cisco Multicast Source Discovery Protocol (MSDP) router must be configured to filter received source-active multicast advertisements for any undesirable multicast groups and sources. Vuln_Discuss The interoperability of BGP extensions for interdomain multicast routing and MSDP enables seamless connectivity of multicast domains between autonomous systems. MP-BGP advertises the unicast prefixes of the multicast sources used by Protocol Independent Multicast (PIM) routers to perform RPF checks and build multicast distribution trees. MSDP is a mechanism used to connect multiple PIM sparse-mode domains, allowing RPs from different domains to share information about active sources. When RPs in peering multicast domains hear about active sources, they can pass on that information to their local receivers, thereby allowing multicast data to be forwarded between the domains. Configuring an import policy to block multicast advertisements for reserved, Martian, single-source multicast, and any other undesirable multicast groups, as well as any source-group (S, G) states with Bogon source addresses, would assist in avoiding unwanted multicast traffic from traversing the core. Check_Content Review the router configuration to determine if there is import policy to block source-active multicast advertisements for any undesirable multicast groups, as well as any (S, G) states with undesirable source addresses. Step 1: Verify that an inbound source-active filter is bound to each MSDP peer. ip msdp peer x.1.28.2 remote-as 2 ip msdp sa-filter in x.1.28.2 list INBOUND_MSDP_SA_FILTER Step 2: Review the access lists referenced by the source-active filter to verify that undesirable multicast groups, auto-RP, single-source multicast (SSM) groups, and advertisements from undesirable sources are blocked. ip access-list extended INBOUND_MSDP_SA_FILTER deny ip any host 224.0.1.3 log deny ip any host 224.0.1.24 log deny ip any host 224.0.1.22 log deny ip any host 224.0.1.2 log deny ip any host 224.0.1.35 log deny ip any host 224.0.1.60 log deny ip any host 224.0.1.39 log deny ip any host 224.0.1.40 log deny ip any 232.0.0.0 0.255.255.255 log deny ip any 239.0.0.0 0.255.255.255 log deny ip 10.0.0.0 0.255.255.255 any log deny ip 127.0.0.0 0.255.255.255 any log deny ip 172.16.0.0 0.15.255.255 any log deny ip 192.168.0.0 0.0.255.255 any log permit ip any any log If the router is not configured with an import policy to filter undesirable SA multicast advertisements, this is a finding. Fix_Text Configure the MSDP router to filter received source-active multicast advertisements for any undesirable multicast groups and sources as shown in the example below. R8(config)#ip access-list extended INBOUND_MSDP_SA_FILTER R8(config-ext-nacl)#deny ip any host 224.0.1.3 log ! Rwhod R8(config-ext-nacl)#deny ip any host 224.0.1.24 log ! Microsoft-ds R8(config-ext-nacl)#deny ip any host 224.0.1.22 log ! SVRLOC R8(config-ext-nacl)#deny ip any host 224.0.1.2 log ! SGI-Dogfight R8(config-ext-nacl)#deny ip any host 224.0.1.35 log ! SVRLOC-DA R8(config-ext-nacl)#deny ip any host 224.0.1.60 log ! hp-device-disc R8(config-ext-nacl)#deny ip any host 224.0.1.39 log ! Auto-RP R8(config-ext-nacl)#deny ip any host 224.0.1.40 log ! Auto-RP R8(config-ext-nacl)#deny ip any 232.0.0.0 0.255.255.255 log ! SSM range R8(config-ext-nacl)#deny ip any 239.0.0.0 0.255.255.255 log ! Admin scoped range R8(config-ext-nacl)#deny ip 10.0.0.0 0.255.255.255 any log ! RFC 1918 address range R8(config-ext-nacl)#deny ip 127.0.0.0 0.255.255.255 any log ! RFC 1918 address range R8(config-ext-nacl)#deny ip 172.16.0.0 0.15.255.255 any log ! RFC 1918 address range R8(config-ext-nacl)#deny ip 192.168.0.0 0.0.255.255 any log ! RFC 1918 address range R8(config-ext-nacl)#permit ip any any log R8(config-ext-nacl)#exit R8(config)#ip msdp sa-filter in x.1.28.2 list INBOUND_MSDP_SA_FILTER Not_Reviewed Vuln_Num V-216636 Rule_ID SV-216636r1117236_rule Severity low Rule_Title The Cisco Multicast Source Discovery Protocol (MSDP) router must be configured to filter source-active multicast advertisements to external MSDP peers to avoid global visibility of local-only multicast sources and groups. Vuln_Discuss To avoid global visibility of local information, there are a number of source-group (S, G) states in a PIM-SM domain that must not be leaked to another domain, such as multicast sources with private address, administratively scoped multicast addresses, and the auto-RP groups (224.0.1.39 and 224.0.1.40). Allowing a multicast distribution tree, local to the core, to extend beyond its boundary could enable local multicast traffic to leak into other autonomous systems and customer networks. Check_Content Review the router configuration to determine if there is export policy to block local source-active multicast advertisements. Step 1: Verify that an outbound source-active filter is bound to each MSDP peer as shown in the example below. ip msdp peer 10.1.28.8 remote-as 8 ip msdp sa-filter out 10.1.28.8 list OUTBOUND_MSDP_SA_FILTER Step 2: Review the access lists referenced by the source-active filters and verify that MSDP source-active messages being sent to MSDP peers do not leak advertisements that are local. ip access-list extended OUTBOUND_MSDP_SA_FILTER deny ip 10.0.0.0 0.255.255.255 any permit ip any any If the router is not configured with an export policy to filter local source-active multicast advertisements, this is a finding. Fix_Text Configure the router with an export policy avoid global visibility of local multicast (S, G) states. The example below will prevent exporting multicast active sources belonging to the private network. R8(config)#ip access-list extended OUTBOUND_MSDP_SA_FILTER R8(config-ext-nacl)#deny ip 10.0.0.0 0.255.255.255 any R8(config-ext-nacl)#permit ip any any R8(config-ext-nacl)#exit R8(config)#ip msdp sa-filter in x.1.28.2 list OUTBOUND_MSDP_SA_FILTER Not_Reviewed Vuln_Num V-216637 Rule_ID SV-216637r1117236_rule Severity low Rule_Title The Cisco Multicast Source Discovery Protocol (MSDP) router must be configured to limit the amount of source-active messages it accepts on a per-peer basis. Vuln_Discuss To reduce any risk of a denial-of-service (DoS) attack from a rogue or misconfigured MSDP router, the router must be configured to limit the number of source-active messages it accepts from each peer. Check_Content Review the router configuration to determine if it is configured to limit the amount of source-active messages it accepts on a per-peer basis. ip msdp peer x.1.28.2 remote-as nn ip msdp sa-filter in 10.1.28.2 list MSDP_SA_FILTER ip msdp sa-limit X.1.28.2 nnn If the router is not configured to limit the source-active messages it accepts, this is a finding. Fix_Text Configure the router to limit the amount of source-active messages it accepts from each peer. R8(config)#ip msdp sa-limit x.1.28.2 nnn Not_Reviewed Vuln_Num V-216638 Rule_ID SV-216638r991846_rule Severity low Rule_Title The Cisco Multicast Source Discovery Protocol (MSDP) router must be configured to use a loopback address as the source address when originating MSDP traffic. Vuln_Discuss Using a loopback address as the source address offers a multitude of uses for security, access, management, and scalability of MSDP routers. It is easier to construct appropriate ingress filters for router management plane traffic destined to the network management subnet since the source addresses will be from the range used for loopback interfaces instead of a larger range of addresses used for physical interfaces. Log information recorded by authentication and syslog servers will record the router’s loopback address instead of the numerous physical interface addresses. Check_Content Verify that the loopback interface is used as the source address for all MSDP packets generated by the router. ip msdp peer x.44.2.34 connect-source Loopback12 remote-as nn If the router does not use its loopback address as the source address when originating MSDP traffic, this is a finding. Fix_Text Configure the router to use its loopback address is used as the source address when sending MSDP packets. R2(config)#ip msdp peer x.44.2.34 connect-source lo12 remote-as nn Not_Reviewed Vuln_Num V-216989 Rule_ID SV-216989r945858_rule Severity high Rule_Title The Cisco perimeter router must be configured to restrict it from accepting outbound IP packets that contain an illegitimate address in the source address field via egress filter or by enabling Unicast Reverse Path Forwarding (uRPF). Vuln_Discuss A compromised host in an enclave can be used by a malicious platform to launch cyberattacks on third parties. This is a common practice in "botnets", which are a collection of compromised computers using malware to attack other computers or networks. DDoS attacks frequently leverage IP source address spoofing to send packets to multiple hosts that in turn will then send return traffic to the hosts with the IP addresses that were forged. This can generate significant amounts of traffic. Therefore, protection measures to counteract IP source address spoofing must be taken. When uRPF is enabled in strict mode, the packet must be received on the interface that the device would use to forward the return packet; thereby mitigating IP source address spoofing. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to verify uRPF or an egress ACL has been configured on all internal interfaces to restrict the router from accepting outbound IP packets that contain an illegitimate address in the source address field. uRPF example interface GigabitEthernet0/1 description downstream link to LAN ip address 10.1.25.5 255.255.255.0 ip verify unicast source reachable-via rx Egress ACL example interface GigabitEthernet0/1 description downstream link to LAN ip address 10.1.25.5 255.255.255.0 ip access-group EGRESS_FILTER in … … … ip access-list extended EGRESS_FILTER permit udp 10.1.15.0 0.0.0.255 any eq domain permit tcp 10.1.15.0 0.0.0.255 any eq ftp permit tcp 10.1.15.0 0.0.0.255 any eq ftp-data permit tcp 10.1.15.0 0.0.0.255 any eq www permit icmp 10.1.15.0 0.0.0.255 any permit icmp 10.1.15.0 0.0.0.255 any echo deny ip any any If uRPF or an egress ACL to restrict the router from accepting outbound IP packets that contain an illegitimate address in the source address field has not been configured on all internal interfaces in an enclave, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure the router to ensure that an egress ACL or uRPF is configured on internal interfaces to restrict the router from accepting any outbound IP packet that contains an illegitimate address in the source field. The example below enables uRPF. R5(config)#int g0/1 R5(config-if)#ip verify unicast source reachable-via rx Not_Reviewed Vuln_Num V-216990 Rule_ID SV-216990r945859_rule Severity medium Rule_Title The Cisco perimeter router must be configured to block all packets with any IP options. Vuln_Discuss Packets with IP options are not fast switched and henceforth must be punted to the router processor. Hackers who initiate denial-of-service (DoS) attacks on routers commonly send large streams of packets with IP options. Dropping the packets with IP options reduces the load of IP options packets on the router. The end result is a reduction in the effects of the DoS attack on the router and on downstream routers. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if it will block all packets with IP options. ip access-list extended EXTERNAL_ACL permit tcp any any established deny ip any any option any-options permit … … … … deny ip any any log-input If the router is not configured to drop all packets with IP options, this is a finding. Fix_Text This requirement is not applicable for the DODIN Backbone. Configure the router to drop all packets with IP options. R1(config)#ip access-list extended EXTERNAL_ACL R1(config-ext-nacl)#15 deny ip any any option any-options Not_Reviewed Vuln_Num V-216991 Rule_ID SV-216991r856208_rule Severity low Rule_Title The Cisco BGP router must be configured to enable the Generalized TTL Security Mechanism (GTSM). Vuln_Discuss As described in RFC 3682, GTSM is designed to protect a router's IP-based control plane from DoS attacks. Many attacks focused on CPU load and line-card overload can be prevented by implementing GTSM on all Exterior Border Gateway Protocol speaking routers. GTSM is based on the fact that the vast majority of control plane peering is established between adjacent routers; that is, the Exterior Border Gateway Protocol peers are either between connecting interfaces or between loopback interfaces. Since TTL spoofing is considered nearly impossible, a mechanism based on an expected TTL value provides a simple and reasonably robust defense from infrastructure attacks based on forged control plane traffic. Check_Content Review the BGP configuration to verify that TTL security has been configured for each external neighbor as shown in the example below. router bgp xx no synchronization bgp log-neighbor-changes neighbor x.1.1.9 remote-as yy neighbor x.1.1.9 password xxxxxxxx neighbor x.1.1.9 ttl-security hops 1 neighbor x.2.1.7 remote-as zz neighbor x.2.1.7 password xxxxxxxx neighbor x.2.1.7 ttl-security hops 1 If the router is not configured to use GTSM for all Exterior Border Gateway Protocol peering sessions, this is a finding. Fix_Text Configure TTL security on all external BGP neighbors as shown in the example below. R1(config)#router bgp xx R1(config-router)#neighbor x.1.1.9 ttl-security hops 1 R1(config-router)#neighbor x.2.1.7 ttl-security hops 1 Not_Reviewed Vuln_Num V-216992 Rule_ID SV-216992r945862_rule Severity medium Rule_Title The Cisco BGP router must be configured to use a unique key for each autonomous system (AS) that it peers with. Vuln_Discuss If the same keys are used between eBGP neighbors, the chance of a hacker compromising any of the BGP sessions increases. It is possible that a malicious user exists in one autonomous system who would know the key used for the eBGP session. This user would then be able to hijack BGP sessions with other trusted neighbors. Check_Content This check is Not Applicable for JRSS internal EBGP use. Review the BGP configuration to determine if it is peering with multiple autonomous systems. Interview the ISSM and router administrator to determine if unique keys are being used. router bgp xx no synchronization bgp log-neighbor-changes neighbor x.1.1.9 remote-as yy neighbor x.1.1.9 password yyyyyyyy neighbor x.2.1.7 remote-as zz neighbor x.2.1.7 password zzzzzzzzz If unique keys are not being used, this is a finding. Fix_Text Configure the router to use unique keys for each AS that it peers with as shown in the example below. R1(config)#router bgp xx R1(config-router)#neighbor x.1.1.9 password yyyyyyyy R1(config-router)#neighbor x.2.1.7 password zzzzzzzzz Not_Reviewed Vuln_Num V-216993 Rule_ID SV-216993r945860_rule Severity medium Rule_Title The Cisco PE router must be configured to drop all packets with any IP options. Vuln_Discuss Packets with IP options are not fast switched and therefore must be punted to the router processor. Hackers who initiate denial-of-service (DoS) attacks on routers commonly send large streams of packets with IP options. Dropping the packets with IP options reduces the load of IP options packets on the router. The end result is a reduction in the effects of the DoS attack on the router and on downstream routers. Check_Content Review the router configuration to determine if it will drop all packets with IP options as shown below. ip options drop If the router is not configured to drop all packets with IP options, this is a finding. Fix_Text Configure the router to drop all packets with IP options as shown below. R4(config)#ip options drop Not_Reviewed Vuln_Num V-229030 Rule_ID SV-229030r878127_rule Severity medium Rule_Title The Cisco router must be configured to have Cisco Express Forwarding enabled. Vuln_Discuss The Cisco Express Forwarding (CEF) switching mode replaces the traditional Cisco routing cache with a data structure that mirrors the entire system routing table. Because there is no need to build cache entries when traffic starts arriving for new destinations, CEF behaves more predictably when presented with large volumes of traffic addressed to many destinations—such as a SYN flood attacks that. Because many SYN flood attacks use randomized source addresses to which the hosts under attack will reply to, there can be a substantial amount of traffic for a large number of destinations that the router will have to handle. Consequently, routers configured for CEF will perform better under SYN floods directed at hosts inside the network than routers using the traditional cache. Check_Content Review the router to verify that CEF is enabled. IPv4 Example: ip cef IPv6 Example: ipv6 cef If CEF is not enabled, this is a finding. Fix_Text Enable CEF IPv4 Example: ip cef IPv6 Example: ipv6 cef Not_Reviewed Vuln_Num V-230038 Rule_ID SV-230038r531386_rule Severity low Rule_Title The Cisco router must be configured to advertise a hop limit of at least 32 in Router Advertisement messages for IPv6 stateless auto-configuration deployments. Vuln_Discuss The Neighbor Discovery protocol allows a hop limit value to be advertised by routers in a Router Advertisement message being used by hosts instead of the standardized default value. If a very small value was configured and advertised to hosts on the LAN segment, communications would fail due to the hop limit reaching zero before the packets sent by a host reached its destination. Check_Content Review the router configuration to determine if the hop limit has been configured for Router Advertisement messages as shown in the example. ipv6 hop-limit 128 If it has been configured and has not been set to at least 32, it is a finding. Fix_Text Configure the router to advertise a hop limit of at least 32 in Router Advertisement messages. R1(config)#ipv6 hop-limit 128 Not_Reviewed Vuln_Num V-230041 Rule_ID SV-230041r532998_rule Severity medium Rule_Title The Cisco router must not be configured to use IPv6 Site Local Unicast addresses. Vuln_Discuss As currently defined, site local addresses are ambiguous and can be present in multiple sites. The address itself does not contain any indication of the site to which it belongs. The use of site-local addresses has the potential to adversely affect network security through leaks, ambiguity, and potential misrouting as documented in section 2 of RFC3879. RFC3879 formally deprecates the IPv6 site-local unicast prefix FEC0::/10 as defined in RFC3513. Check_Content Review the router configuration to ensure FEC0::/10 IPv6 addresses are not defined. If IPv6 Site Local Unicast addresses are defined, this is a finding. Fix_Text Configure the router using only authorized IPv6 addresses. Not_Reviewed Vuln_Num V-230044 Rule_ID SV-230044r533005_rule Severity medium Rule_Title The Cisco perimeter router must be configured to suppress Router Advertisements on all external IPv6-enabled interfaces. Vuln_Discuss Many of the known attacks in stateless autoconfiguration are defined in RFC 3756 were present in IPv4 ARP attacks. To mitigate these vulnerabilities, links that have no hosts connected such as the interface connecting to external gateways must be configured to suppress router advertisements. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to verify that Router Advertisements are suppressed on all external IPv6-enabled interfaces as shown in the example below. interface gigabitethernet1/0 ipv6 address 2001::1:0:22/64 ipv6 nd ra suppress If the router is not configured to suppress Router Advertisements on all external IPv6-enabled interfaces, this is a finding. Fix_Text Configure the router to suppress Router Advertisements on all external IPv6-enabled interfaces as shown in the example below. R1(config)#int g1/0 R1(config-if)#ipv6 nd ra suppress R1(config-if)#end Not_Reviewed Vuln_Num V-230047 Rule_ID SV-230047r950991_rule Severity medium Rule_Title The Cisco perimeter router must be configured to drop IPv6 undetermined transport packets. Vuln_Discuss One of the fragmentation weaknesses known in IPv6 is the undetermined transport packet. This packet contains an undetermined protocol due to fragmentation. Depending on the length of the IPv6 extension header chain, the initial fragment may not contain the layer four port information of the packet. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if it is configured to drop IPv6 undetermined transport packets. Step 1: Verify that an inbound IPv6 ACL has been configured on the external interface. interface gigabitethernet1/0 ipv6 address 2001::1:0:22/64 ipv6 traffic-filter FILTER_IPV6 in Step 2: Verify that the ACL drops undetermined transport packets as shown in the example below. ipv6 access-list FILTER_IPV6 deny ipv6 any any log undetermined-transport permit ipv6 … … … … deny ipv6 any any log If the router is not configured to drop IPv6 undetermined transport packets, this is a finding. Fix_Text Configure the router to drop IPv6 undetermined transport packets as shown in the example below. R1(config)#ipv6 access-list FILTER_IPV6 R1(config-ipv6-acl)#deny ipv6 any any undetermined-transport log R1(config-ipv6-acl)#permit ipv6 … … … … R1(config-ipv6-acl)#deny ipv6 any any log R1(config-ipv6-acl)#exit R1(config)#int g1/0 R1(config-if)#ipv6 traffic-filter FILTER_IPV6 in Not_Reviewed Vuln_Num V-230050 Rule_ID SV-230050r856665_rule Severity medium Rule_Title The Cisco perimeter router must be configured drop IPv6 packets with a Routing Header type 0, 1, or 3–255. Vuln_Discuss The routing header can be used maliciously to send a packet through a path where less robust security is in place, rather than through the presumably preferred path of routing protocols. Use of the routing extension header has few legitimate uses other than as implemented by Mobile IPv6. The Type 0 Routing Header (RFC 5095) is dangerous because it allows attackers to spoof source addresses and obtain traffic in response, rather than the real owner of the address. Secondly, a packet with an allowed destination address could be sent through a Firewall using the Routing Header functionality, only to bounce to a different node once inside. The Type 1 Routing Header is defined by a specification called "Nimrod Routing", a discontinued project funded by DARPA. Assuming that most implementations will not recognize the Type 1 Routing Header, it must be dropped. The Type 3–255 Routing Header values in the routing type field are currently undefined and should be dropped inbound and outbound. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if it is configured to drop IPv6 packets containing a Routing Header of type 0, 1, or 3-255. Step 1: Verify that an inbound IPv6 ACL has been configured on the external interface. interface gigabitethernet1/0 ipv6 address 2001::1:0:22/64 ipv6 traffic-filter FILTER_IPV6 in Step 2: Verify that the ACL drops IPv6 packets with a Routing Header type 0, 1, or 3-255 as shown in the example below. ipv6 access-list FILTER_IPV6 permit ipv6 any host 2001:DB8::1:1:1234 routing-type 2 deny ipv6 any any log routing permit ipv6 … … … … deny ipv6 any any log Note: The example above allows routing-type 2 in the event Mobility IPv6 is deployed. If the router is not configured to drop IPv6 packets containing a Routing Header of type 0, 1, or 3-255, this is a finding. Fix_Text Configure the router to drop IPv6 packets with Routing Header of type 0, 1, or 3-255 as shown in the example below. R1(config)#ipv6 access-list FILTER_IPV6 R1(config-ipv6-acl)#permit ipv6 any host 2001:DB8::0:1:1:1234 routing-type 2 R1(config-ipv6-acl)#deny ipv6 any any routing log R1(config-ipv6-acl)#permit … … … … R1(config-ipv6-acl)#deny ipv6 any any log R1(config-ipv6-acl)#exit R1(config)#int g1/0 R1(config-if)#ipv6 traffic-filter FILTER_IPV6 Not_Reviewed Vuln_Num V-230145 Rule_ID SV-230145r1132551_rule Severity medium Rule_Title The Cisco perimeter router must be configured to drop IPv6 packets containing a Hop-by-Hop header with invalid option type values. Vuln_Discuss These options are intended to be for the Destination Options header only. The optional and extensible natures of the IPv6 extension headers require higher scrutiny since many implementations do not always drop packets with headers that it cannot recognize and hence could cause a Denial-of-Service on the target device. In addition, the type, length, value (TLV) formatting provides the ability for headers to be very large. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if it is compliant with this requirement. Step 1: Verify that an inbound IPv6 ACL has been configured on the external interface. interface gigabitethernet1/0 ipv6 address 2001::1:0:22/64 ipv6 traffic-filter FILTER_IPV6 in Step 2: Verify that the ACL drops IPv6 packets containing a Hop-by-Hop header with destination options as shown in the example below. ipv6 access-list FILTER_IPV6 deny hbh any any dest-option log permit ipv6 … … … … deny ipv6 any any log Note: Cisco has deprecated the dest-option-type command used to filter by option type within the Hop-by-Hop header. Therefore, all packets with the Hop-by-Hop header option types must be dropped. If the router is not configured to drop IPv6 packets containing a Hop-by-Hop header with destination options, this is a finding. Fix_Text Drop IPv6 packets containing a Hop-by-Hop header as shown in the example below. R1(config)#ipv6 access-list FILTER_IPV6 R1(config-ipv6-acl)#deny hbh any any dest-option log R1(config-ipv6-acl)# permit ipv6 … … … … R1(config-ipv6-acl)#deny ipv6 any any log R1(config-ipv6-acl)#exit R1(config)#int g1/0 R1(config-if)#ipv6 traffic-filter FILTER_IPV6 R1(config-if)#end Not_Reviewed Vuln_Num V-230149 Rule_ID SV-230149r1132504_rule Severity medium Rule_Title The Cisco perimeter router must be configured to drop IPv6 packets containing a Destination Option header with invalid option type values. Vuln_Discuss These options are intended to be for the Hop-by-Hop header only. The optional and extensible natures of the IPv6 extension headers require higher scrutiny since many implementations do not always drop packets with headers that it cannot recognize. Hence, this could cause a Denial-of-Service on the target device. In addition, the type, length, value (TLV) formatting provides the ability for headers to be very large. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if it is compliant with this requirement. Step 1: Verify that an inbound IPv6 ACL has been configured on the external interface. interface gigabitethernet1/0 ipv6 address 2001::1:0:22/64 ipv6 traffic-filter FILTER_IPV6 in Step 2: Verify that the ACL drops IPv6 packets containing a Destination Option header with option type values of 0x05 (Router Alert) or 0xC2 (Jumbo Payload) as shown in the example below. ipv6 access-list FILTER_IPV6 deny 60 any any dest-option log permit ipv6 … … … … deny ipv6 any any log Note: Cisco has deprecated the dest-option-type command used to filter by option type within the Destination Option header. Therefore, all packets with the Destination Option header must be dropped. If the router is not configured to drop IPv6 packets containing a Destination Option header, this is a finding. Fix_Text Configure the router to drop IPv6 packets containing a Destination Option header as shown in the example below. R1(config)#ipv6 access-list FILTER_IPV6 R1(config-ipv6-acl)#deny 60 any any dest-option log R1(config-ipv6-acl)#permit … … … … R1(config-ipv6-acl)#deny ipv6 any any log R1(config-ipv6-acl)#exit R1(config)#int g1/0 R1(config-if)#ipv6 traffic-filter FILTER_IPV6 R1(config-if)#end Not_Reviewed Vuln_Num V-230152 Rule_ID SV-230152r1132507_rule Severity medium Rule_Title The Cisco perimeter router must be configured to drop IPv6 packets containing an extension header with the Endpoint Identification option. Vuln_Discuss The optional and extensible natures of the IPv6 extension headers require higher scrutiny since many implementations do not always drop packets with headers that it cannot recognize, and hence could cause a Denial-of-Service on the target device. In addition, the type, length, value (TLV) formatting provides the ability for headers to be very large. This option type is associated with the Nimrod Routing system and has no defining RFC document. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if it is compliant with this requirement. Step 1: Verify that an inbound IPv6 ACL has been configured on the external interface. interface gigabitethernet1/0 ipv6 address 2001::1:0:22/64 ipv6 traffic-filter FILTER_IPV6 in Step 2: Verify that the ACL drops IPv6 packets containing a Destination Option header as shown in the example below. ipv6 access-list FILTER_IPV6 deny 60 any any dest-option log permit ipv6 … … … … deny ipv6 any any log Note: Cisco has deprecated the dest-option-type command used to filter by option type within the Destination Option header. Therefore, all packets with the Destination Option header must be dropped. If the router is not configured to drop IPv6 packets containing a Destination Option header, this is a finding. Fix_Text Configure the router to drop IPv6 packets containing an option type value of 0x8A (Endpoint Identification) regardless of whether it appears in a Hop-by-Hop or Destination Option header as shown in the example below. R1(config)#ipv6 access-list FILTER_IPV6 R1(config-ipv6-acl)#deny 60 any any dest-option log R1(config-ipv6-acl)#deny hbh any any dest-option log R1(config-ipv6-acl)#permit … … … … R1(config-ipv6-acl)#deny ipv6 any any log R1(config-ipv6-acl)#exit R1(config)#int g1/0 R1(config-if)#ipv6 traffic-filter FILTER_IPV6 R1(config-if)#end Not_Reviewed Vuln_Num V-230155 Rule_ID SV-230155r1132510_rule Severity medium Rule_Title The Cisco perimeter router must be configured to drop IPv6 packets containing the NSAP address option within Destination Option header. Vuln_Discuss The optional and extensible natures of the IPv6 extension headers require higher scrutiny since many implementations do not always drop packets with headers that it cannot recognize, and hence could cause a Denial-of-Service on the target device. In addition, the type, length, value (TLV) formatting provides the ability for headers to be very large. This option type from RFC 1888 (OSI NSAPs and IPv6) has been deprecated by RFC 4048. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if it is compliant with this requirement. Step 1: Verify that an inbound IPv6 ACL has been configured on the external interface. interface gigabitethernet1/0 ipv6 address 2001::1:0:22/64 ipv6 traffic-filter FILTER_IPV6 in Step 2: Verify that the ACL drops IPv6 packets containing a Destination Option header as shown in the example below. ipv6 access-list FILTER_IPV6 deny 60 any any dest-option log permit ipv6 … … … … deny ipv6 any any log Note: Cisco has deprecated the dest-option-type command used to filter by option type within the Destination Option header. Therefore, all packets with the Destination Option header must be dropped. If the router is not configured to drop IPv6 packets containing a Destination Option header, this is a finding. Fix_Text Configure the router to drop IPv6 packets containing a Destination Option header as shown in the example below. R1(config)#ipv6 access-list FILTER_IPV6 R1(config-ipv6-acl)#deny 60 any any dest-option log R1(config-ipv6-acl)#permit … … … … R1(config-ipv6-acl)#deny ipv6 any any log R1(config-ipv6-acl)#exit R1(config)#int g1/0 R1(config-if)#ipv6 traffic-filter FILTER_IPV6 R1(config-if)#end Not_Reviewed Vuln_Num V-230158 Rule_ID SV-230158r1132513_rule Severity medium Rule_Title The Cisco perimeter router must be configured to drop IPv6 packets containing a Hop-by-Hop or Destination Option extension header with an undefined option type. Vuln_Discuss The optional and extensible natures of the IPv6 extension headers require higher scrutiny since many implementations do not always drop packets with headers that it cannot recognize, and hence could cause a Denial-of-Service on the target device. In addition, the type, length, value (TLV) formatting provides the ability for headers to be very large. Check_Content This requirement is not applicable for the DODIN Backbone. Review the router configuration to determine if it is compliant with this requirement. Step 1: Verify that an inbound IPv6 ACL has been configured on the external interface. interface gigabitethernet1/0 ipv6 address 2001::1:0:22/64 ipv6 traffic-filter FILTER_IPV6 in Step 2: Verify that the ACL drops IPv6 packets containing a Destination Option header as shown in the example below. ipv6 access-list FILTER_IPV6 deny 60 any any dest-option log deny hbh any any dest-option log permit ipv6 … … … … deny ipv6 any any log Note: Cisco has deprecated the dest-option-type command used to filter by option type within the Destination Option and Hop-by-Hop header. Therefore, all packets with the Destination Option header and Hop-by-Hop options must be dropped. If the router is not configured to drop IPv6 packets containing a Destination Option header, this is a finding. Fix_Text Configure the router to drop all inbound IPv6 packets containing destination option type values regardless of whether they appear in a Hop-by-Hop or Destination Option header as shown in the example below. R1(config)#ipv6 access-list FILTER_IPV6 R1(config-ipv6-acl)#deny 60 any any dest-option log R1(config-ipv6-acl)#deny hbh any any dest-option log R1(config-ipv6-acl)#permit … … … … R1(config-ipv6-acl)#deny ipv6 any any log R1(config-ipv6-acl)#exit R1(config)#int g1/0 R1(config-if)#ipv6 traffic-filter FILTER_IPV6 R1(config-if)#end Not_Reviewed