Rule ID
SV-273618r1111065_rule
Version
V1R1
CCIs
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. Distributed denial-of-service (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.
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: reverse-path-check ! interface ethernet 1/1/1 port-name downstream_link_to_LAN ip address 10.1.25.5 255.255.255.0 rpf-mode loose Egress ACL example: interface ethernet 1/2/2 port-name downstream_link_to_LAN ip address 10.1.25.5 255.255.255.0 ip access-group EGRESS_FILTER in logging enable ! … … … ip access-list extended EGRESS_FILTER sequence 10 permit udp 10.1.15.0 0.0.0.255 any eq dns sequence 20 permit tcp 10.1.15.0 0.0.0.255 any eq ftp sequence 30 permit tcp 10.1.15.0 0.0.0.255 any eq ftp-data sequence 40 permit tcp 10.1.15.0 0.0.0.255 any eq http sequence 50 permit tcp 10.1.15.0 0.0.0.255 any eq ssl sequence 60 permit icmp 10.1.15.0 0.0.0.255 any sequence 70 permit icmp 10.1.15.0 0.0.0.255 any echo sequence 80 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.
This requirement is not applicable for the DODIN Backbone. Configure the router to ensure 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. uRPF: ICX(config)#reverse-path-check ICX(config)#interface ethernet 1/2/2 ICX(config-if-e10000-1/2/2)#rpf-mode loose ACL: ICX(config)#ip access ext EGRESS_FILTER ICX(config-ext-ipacl-EGRESS_FILTER)#permit udp 10.1.15.0/24 any eq dns ICX(config-ext-ipacl-EGRESS_FILTER)#permit tcp 10.1.15.0/24 any eq ftp ICX(config-ext-ipacl-EGRESS_FILTER)#permit tcp 10.1.15.0/24 any eq ftp-data ICX(config-ext-ipacl-EGRESS_FILTER)#permit tcp 10.1.15.0/24 any eq http ICX(config-ext-ipacl-EGRESS_FILTER)#permit tcp 10.1.15.0/24 any eq http ICX(config-ext-ipacl-EGRESS_FILTER)#permit tcp 10.1.15.0/24 any eq ssl ICX(config-ext-ipacl-EGRESS_FILTER)#permit icmp 10.1.15.0/24 any ICX(config-ext-ipacl-EGRESS_FILTER)#permit icmp 10.1.15.0/24 any echo ICX(config-ext-ipacl-EGRESS_FILTER)#deny ip any any ICX(config)#interface ethernet 1/2/2 ICX(config-if-e10000-1/2/2)#port-name downstream_link_to_LAN ICX(config-if-e10000-1/2/2)#ip addr 10.1.25.5/24 ICX(config-if-e10000-1/2/2)#ip access-group EGRESS_FILTER in logging enable