{"stig":{"title":"Microsoft Exchange 2019 Edge Server Security Technical Implementation Guide","version":"2","release":"2"},"checks":[{"vulnId":"V-259577","ruleId":"SV-259577r960759_rule","severity":"medium","ruleTitle":"SchUseStrongCrypto must be enabled.","description":"Exchange Server 2019 is configured by default with TLS 1.2. However, SchUseStrongCrypto is not set by default and must be configured to meet the TLS requirement. The strong cryptography (configured by the SchUseStrongCrypto registry value) uses more secure network protocols (TLS 1.2, TLS 1.1, and TLS 1.0) and blocks protocols that are not secure. SchUseStrongCrypto affects only client (outgoing) connections in the application.","checkContent":"In a PowerShell window, run the following commands:\n\nGet-ItemProperty HKLM:\\SOFTWARE\\Microsoft\\.NetFramework\\v4.0.30319\n\nIf the value \"SchUseStrongCrypto\" is not present and set to 1, this is a finding.","fixText":"In a PowerShell window with elevated privileges, run the following commands:\n\nreg add HKLM\\SOFTWARE\\Microsoft\\.NetFramework\\v4.0.30319 /v \"SchUseStrongCrypto\" /t REG_DWORD /d 1\n\nreg add HKLM\\SOFTWARE\\WoW6432Node\\Microsoft\\.NetFramework\\v4.0.30319 /v \"SchUseStrongCrypto\" /t REG_DWORD /d 1\n\nThis will create the value within the necessary key and set the data to 1.","ccis":["CCI-000068"]},{"vulnId":"V-259578","ruleId":"SV-259578r960792_rule","severity":"medium","ruleTitle":"Exchange servers must use approved DOD certificates.","description":"To mitigate the risk of unauthorized access to sensitive information by entities that have been issued certificates by DOD-approved PKIs, all DOD systems (e.g., networks, web servers, and web portals) must be properly configured to incorporate access control methods that do not rely solely on the possession of a certificate for access. Successful authentication must not automatically give an entity access to an asset or security boundary. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset. Information systems use access control policies and enforcement mechanisms to implement this requirement. \n\nAccess control policies include identity-based policies, role-based policies, and attribute-based policies. Access enforcement mechanisms include access control lists, access control matrices, and cryptography. These policies and mechanisms must be employed by the application to control access between users (or processes acting on behalf of users) and objects (e.g., devices, files, records, processes, programs, and domains) in the information system. \n\nThis requirement is applicable to access control enforcement applications (e.g., authentication servers) and other applications that perform information and system access control functions.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ExchangeCertificate | Select-Object -Property CertificateDomains, issuer\n\nIf the value of \"CertificateDomains\" does not indicate it is issued by the DOD, this is a finding.","fixText":"Remove the non-DOD certificate and import the correct DOD certificates.","ccis":["CCI-000213"]},{"vulnId":"V-259579","ruleId":"SV-259579r960801_rule","severity":"medium","ruleTitle":"Exchange must have accepted domains configured.","description":"Exchange may be configured to accept email for multiple domain names. This setting identifies the domains for which the server will accept mail. This check verifies the email server is not accepting email for unauthorized domains.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the Accepted Domain values. \n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-AcceptedDomain | Select-Object -Property Name, DomainName, Identity, Default\n\nIf the value of \"Default\" is not set to \"True\", this is a finding.\n\nor\n\nIf the \"Default\" value for \"AcceptedDomains\" is set to another value other than \"True\" and has signoff and risk acceptance in the EDSP, this is not a finding.","fixText":"Update the EDSP.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-AcceptedDomain -Identity <'IdentityName'> -MakeDefault $true\n\nNote: The value must be in quotes.","ccis":["CCI-001368"]},{"vulnId":"V-259580","ruleId":"SV-259580r960840_rule","severity":"medium","ruleTitle":"Exchange external Receive connectors must be domain secure-enabled.","description":"The Simple Mail Transfer Protocol (SMTP) connector is used by Exchange to send and receive messages from server to server. Several controls work together to provide security between internal servers. This setting controls the authentication method used for communications between servers. With this feature enabled, messages can be securely passed from a partner domain securely.\n\nThe use of secure communication prevents eavesdroppers from reading or modifying communications between mail clients and servers. While sensitive message bodies should be encrypted by the sender at the client, requiring a secure connection from server to server adds protection by encrypting the sender and recipient information that cannot be encrypted by the sender.\n\nIndividually, channel security and encryption can be compromised by attackers. Used together, email becomes a more difficult target, and security is heightened. Failure to enable this feature gives eavesdroppers an opportunity to read or modify messages between servers.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity, DomainSecureEnabled\n\nFor each receive connector, if the value of \"DomainSecureEnabled\" is not set to \"True\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -DomainSecureEnabled $true\n\nNote: The value must be in quotes.\n\nRepeat the procedures for each receive connector.","ccis":["CCI-000044"]},{"vulnId":"V-259581","ruleId":"SV-259581r960879_rule","severity":"medium","ruleTitle":"The Exchange email diagnostic log level must be set to the lowest level.","description":"Log files help establish a history of activities and can be useful in detecting attack attempts or determining tuning adjustments to improve availability. Diagnostic logging, however, characteristically produces large volumes of data and requires care in managing the logs to prevent risk of disk capacity denial of service conditions. \n\nExchange diagnostic logging is broken up into 29 main \"services\", each of which has anywhere from two to 26 \"categories\" of events to be monitored. Moreover, each category may be set to one of four levels of logging: Lowest, Low, CAT II, and High, depending on how much detail one desires. The higher the level of detail, the more disk space required to store the audit material.\n\nDiagnostic logging is intended to help administrators debug problems with their systems, not as a general-purpose auditing tool. Because the diagnostic logs collect a great deal of information, the log files may grow large very quickly. Diagnostic log levels may be raised for limited periods of time when attempting to debug relevant pieces of Exchange functionality. Once debugging has finished, diagnostic log levels should be reduced again.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-EventLogLevel\n\nIf any \"EventLogLevel\" values returned are not set to \"Lowest\", this is a finding.\n\nNote: The default installation of Exchange has all Event Levels set to Lowest with exception of the following:\n\nMSExchange ADAccess\\Topology - Low\nMSExchangeADAccess\\Validation - Low\nMSExchange BackEndRehydration\\Configuration - Low\nMSExchange BackEndRehydration\\Server - 2\nMSExchange OAuth\\Configuration - Low\nMSExchange OAuth\\Server - 2\nMSExchange RBAC\\RBAC - Low\nMSExchangeADTopology\\Topology - Low\n\nAll of these must be set to Lowest.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-EventLogLevel -Identity <'IdentityName\\EventlogName'> -Level Lowest\n\nNote: The value must be in quotes.","ccis":["CCI-000169"]},{"vulnId":"V-259582","ruleId":"SV-259582r960879_rule","severity":"medium","ruleTitle":"Exchange connectivity logging must be enabled.","description":"A connectivity log is a record of the SMTP connection activity of the outbound message delivery queues to the destination mailbox server, smart host, or domain. Connectivity logging is available on Hub Transport servers and Edge Transport servers. By default, connectivity logging is disabled. If events are not recorded, it may be difficult or impossible to determine the root cause of system problems or the unauthorized activities of malicious users.\n\nNote: Transport configuration settings apply to the organization/global level of the Exchange SMTP path. By checking and setting them at the Hub server, the setting will apply to both Hub and Edge roles.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-TransportService | Select-Object -Property Name, Identity, ConnectivityLogEnabled\n\nIf the value of \"ConnectivityLogEnabled\" is not set to \"True\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-TransportService -Identity <'IdentityName'> -ConnectivityLogEnabled $true\n\nNote: The value must be in quotes.","ccis":["CCI-000169"]},{"vulnId":"V-259583","ruleId":"SV-259583r960900_rule","severity":"medium","ruleTitle":"Exchange message tracking logging must be enabled.","description":"A message tracking log provides a detailed log of all message activity as messages are transferred to and from a computer running Exchange.\n\nIf events are not recorded, it may be difficult or impossible to determine the root cause of system problems or the unauthorized activities of malicious users.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-Transportservice | Select-Object -Property Name, MessageTrackingLogEnabled\n\nIf the value of \"MessageTrackingLogEnabled\" is not set to \"True\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-Transportservice -MessageTrackingLogEnabled $true\n\nNote: The value must be in quotes.","ccis":["CCI-000133"]},{"vulnId":"V-259584","ruleId":"SV-259584r960918_rule","severity":"medium","ruleTitle":"Exchange queue monitoring must be configured with threshold and action.","description":"Monitors are automated \"process watchers\" that respond to performance changes and can be useful in detecting outages and alerting administrators where attention is needed. Exchange has built-in monitors that enable the administrator to generate alerts if thresholds are reached, better enabling them to react in a timely fashion.\n\nThis field offers choices of alerts when a \"warning\" or \"critical\" threshold is reached on the SMTP queue. A good rule of thumb (default) is to issue warnings when SMTP queue growth exceeds 10 minutes and critical messages when it exceeds 20 minutes, which should only exist occasionally. Frequent alerts against this counter may indicate a network or other issue (such as inbound spammer traffic) that directly impacts email delivery.\n\nNotification choices include email alert to an email-enabled account (e.g., an email administrator) or invoke a script to take other action (e.g., to add an event to the Microsoft Application Event Log, where external monitors might detect it).","checkContent":"Note: By default, there are two user-defined data collector sets created by Exchange: ExchangeDiagnosticsDailyPerformanceLog and ExchangeDiagnosticsPerformanceLog. These are not providing enough data to monitor SMTP queues per the requirement. Additionally, if a third-party application is performing monitoring functions, the reviewer should verify the application is monitoring correctly and mark the vulnerability Not Applicable.\n\nOpen the Exchange Management Shell and enter the following command:\n\nperfmon\n\nIn the left pane, navigate to Performance >> Data Collector Sets >> User Defined.\n\nIf no sets are defined or queues are not being monitored, this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nperfmon\n\nIn the left pane, navigate to Performance >> Data Collector Sets >> User Defined.\n\nIn left pane, right-click User Defined >> New >> Data Collector Set and configure the system to use the data collection set for monitoring the queues.","ccis":["CCI-000154"]},{"vulnId":"V-259585","ruleId":"SV-259585r960930_rule","severity":"medium","ruleTitle":"Exchange audit data must be protected against unauthorized access (read access).","description":"Log files help establish a history of activities and can be useful in detecting attack attempts or determining tuning adjustments to improve availability. Audit log content must always be considered sensitive and in need of protection. Audit data available for modification by a malicious user can be altered to conceal malicious activity. Audit data might also provide a means for the malicious user to plan unauthorized activities that exploit weaknesses.\n\nThe contents of audit logs are protected against unauthorized access, modification, or deletion. Only authorized auditors and the audit functions should be granted read and write access to audit log data.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the authorized groups or users that should have read access to the audit data.\n\nIf any group or user has read access to the audit data that is not documented in the EDSP, this is a finding.","fixText":"Update the EDSP to reflect the authorized groups or users that should have read access to the audit data.\n\nRestrict any unauthorized groups' or users' read access to the audit logs.","ccis":["CCI-000162"]},{"vulnId":"V-259586","ruleId":"SV-259586r960933_rule","severity":"medium","ruleTitle":"Exchange audit data must be protected against unauthorized access for modification.","description":"Log files help establish a history of activities and can be useful in detecting attack attempts or determining tuning adjustments to improve availability. Audit log content must always be considered sensitive and in need of protection. Audit data available for modification by a malicious user can be altered to conceal malicious activity. Audit data might also provide a means for the malicious user to plan unauthorized activities that exploit weaknesses.\n\nThe contents of audit logs are protected against unauthorized access, modification, or deletion. Only authorized auditors and the audit functions should be granted read and write access to audit log data.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the authorized groups or users that should have modify permissions to the audit data.\n\nIf any group or user has modify permissions for the audit data that is not documented in the EDSP, this is a finding.","fixText":"Update the EDSP to reflect the authorized groups or users that should have modify permissions to the audit data.\n\nRestrict any unauthorized groups' or users' modify permissions for the audit logs.","ccis":["CCI-000163"]},{"vulnId":"V-259587","ruleId":"SV-259587r960936_rule","severity":"medium","ruleTitle":"Exchange audit data must be protected against unauthorized access for deletion.","description":"Log files help establish a history of activities and can be useful in detecting attack attempts or determining tuning adjustments to improve availability. Audit log content must always be considered sensitive and in need of protection. Audit data available for modification by a malicious user can be altered to conceal malicious activity. Audit data might also provide a means for the malicious user to plan unauthorized activities that exploit weaknesses.\n\nThe contents of audit logs are protected against unauthorized access, modification, or deletion. Only authorized auditors and the audit functions should be granted read and write access to audit log data.","checkContent":"Review the Email Domain Security Plan (EDSP). \n\nDetermine the authorized groups or users that should have delete permissions for the audit data.\n\nIf any group or user has delete permissions for the audit data that is not documented in the EDSP, this is a finding.","fixText":"Update the EDSP to reflect the authorized groups or users that should have delete permissions for the audit data.\n\nRestrict any unauthorized groups' or users' delete permissions for the audit logs.","ccis":["CCI-000164"]},{"vulnId":"V-259588","ruleId":"SV-259588r960948_rule","severity":"medium","ruleTitle":"Exchange audit data must be on separate partitions.","description":"Log files help establish a history of activities and can be useful in detecting attack attempts or determining tuning adjustments to improve availability. Audit log content must always be considered sensitive and in need of protection.\n\nSuccessful exploit of an application server vulnerability may well be logged by monitoring or audit processes when it occurs. Writing log and audit data to a separate partition where separate security contexts protect them may offer the ability to protect this information from being modified or removed by the exploit mechanism.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the audit logs' assigned partition.\n\nNote: By default, the logs are located on the application partition in \\Program Files\\Microsoft\\Exchange Server\\V15\\Logging\\.\n\nIf the log files are not on a separate partition from the application, this is a finding.","fixText":"Update the EDSP.\n\nConfigure the audit log location to be on a partition drive separate from the application.","ccis":["CCI-001348"]},{"vulnId":"V-259589","ruleId":"SV-259589r1015762_rule","severity":"medium","ruleTitle":"Exchange local machine policy must require signed scripts.","description":"Scripts often provide a way for attackers to infiltrate a system, especially scripts downloaded from untrusted locations. By setting machine policy to prevent unauthorized script executions, unanticipated system impacts can be avoided. Failure to allow only signed remote scripts reduces the attack vector vulnerabilities from unsigned remote scripts.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ExecutionPolicy\n\nIf the value returned is not \"RemoteSigned\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ExecutionPolicy RemoteSigned","ccis":["CCI-003992","CCI-001749"]},{"vulnId":"V-259590","ruleId":"SV-259590r960963_rule","severity":"medium","ruleTitle":"Exchange must not send customer experience reports to Microsoft.","description":"It is detrimental for applications to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors.\n\nApplications are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions).\n\nExamples of nonessential capabilities include, but are not limited to, advertising software or browser plug-ins not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled.\n\nAll system errors in Exchange will result in outbound traffic that may be identified by an eavesdropper. For this reason, the \"Report Fatal Errors to Microsoft\" feature must be disabled.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-OrganizationConfig | Select-Object -Property Name, Identity, CustomerFeedbackEnabled \n\nIf the value for \"CustomerFeedbackEnabled\" is not set to \"False\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-OrganizationConfig -CustomerFeedbackEnabled $false\n\nNote: This can be done during initial installation of Exchange.","ccis":["CCI-000381"]},{"vulnId":"V-259591","ruleId":"SV-259591r960963_rule","severity":"medium","ruleTitle":"Exchange Send Fatal Errors to Microsoft must be disabled.","description":"It is detrimental for applications to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors.\n\nApplications are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions).\n\nExamples of nonessential capabilities include, but are not limited to, advertising software or browser plug-ins not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled.\n\nCustomer Experience reports in Exchange will result in outbound traffic that may be identified by an eavesdropper. For this reason, the Customer Experience reports to Microsoft must not be sent.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ExchangeServer –status | Select-Object -Property Name, Identity, ErrorReportingEnabled\n\nFor each exchange server, if the value of \"ErrorReportingEnabled\" is not set to \"False\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ExchangeServer -Identity <'IdentityName'> -ErrorReportingEnabled $false\n\nNote: The value must be in quotes.\n\nRepeat the procedure for each identity.","ccis":["CCI-000381"]},{"vulnId":"V-259592","ruleId":"SV-259592r961095_rule","severity":"medium","ruleTitle":"Exchange queue database must reside on a dedicated partition.","description":"In the same way that added security layers can provide a cumulative positive effect on security posture, multiple applications can provide a cumulative negative effect. A vulnerability and subsequent exploit to one application can lead to an exploit of other applications sharing the same security context. For example, an exploit to a web server process that leads to unauthorized administrative access to the host system can most likely lead to a compromise of all applications hosted by the same system.\n\nEmail services should be installed to a discrete set of directories on a partition that does not host other applications. Email services should never be installed on a Domain Controller/Directory Services server.","checkContent":"Open the Exchange Management Shell and run the following command:\n\nGet-Content $exbin\\EdgeTransport.exe.config |Select-String \"QueueDatabasePath\" -SimpleMatch\n\nExample Output:\n\n\n\nIf the path of the Queue Database is in the same volume as the installation of Exchange, this is a finding.\n\nIf the path of the Queue Database is on the same volume of existing applications, this is a finding.","fixText":"It is recommended to follow the instructions found in the following documentation:\nhttps://learn.microsoft.com/en-us/exchange/mail-flow/queues/relocate-queue-database?view=exchserver-2019\n\nSet aside time for maintenance before correcting the issue, as this will affect mail flow through the Edge role on that server.\n\nOpen an Exchange Management Shell and use the automated script (shipped with Exchange) to move the queue database and its existing files to the new destination.\n\nThe following parameters must be answered to successfully complete the move:\n\n-queueDatabasePath #New destination for the Queue Database. If destination does not exist, the script will create it with the appropriate permissions.\n-queueDatabaseLoggingPath #New destination for the Queue Database Logs. If destination does not exist, the script will create it with the appropriate permissions.\n-ipFilterDatabasePath #New destination for the IP filtering Database. If the destination does not exist, the script will create it with the appropriate permissions.\n-ipFilterDatabaseLoggingPath #New destination for the IP filtering Database Logs. If the destination does not exist, the script will create it with the appropriate permissions.\n-temporaryStorage #This will be the path that the script moves the old version of the EdgeTransport.exe.config. The new version will have the updated path.\n\nNote: Always back up the configuration file as CUs will overwrite any added custom configuration.","ccis":["CCI-001082"]},{"vulnId":"V-259593","ruleId":"SV-259593r961101_rule","severity":"medium","ruleTitle":"Exchange internet-facing send connectors must specify a Smart Host.","description":"When identifying a \"Smart Host\" for the email environment, a logical send connector is the preferred method.\n\nA Smart Host acts as an internet-facing concentrator for other email servers. Appropriate hardening can be applied to the Smart Host, rather than at multiple locations throughout the enterprise.\n\nFailure to identify a Smart Host could default to each email server performing its own lookups (potentially through protective firewalls). Exchange servers should not be internet facing and should therefore not perform any Smart Host functions. When the Exchange servers are internet facing, they must be configured to identify the internet-facing server that is performing the Smart Host function.","checkContent":"Note: This is not applicable for SIPR enclaves.\n\nReview the Email Domain Security Plan (EDSP).\n\nDetermine the internet-facing connectors.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-SendConnector | Select-Object -Property Name, Identity, SmartHosts, DNSRoutingEnabled\n\nFor each send connector, if the value of \"SmartHosts\" does not return the Smart Host IP Address and the value for \"DNSRoutingEnabled\" is not set to \"False\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-SendConnector <'IdentityName'> -SmartHosts <'IP Address of Smart Host'> -DNSRoutingEnabled $false \n\nNote: The value must be in quotes.\n\nRepeat the procedure for each send connector.","ccis":["CCI-001178"]},{"vulnId":"V-259594","ruleId":"SV-259594r1043178_rule","severity":"medium","ruleTitle":"Exchange internal send connectors must use domain security (mutual authentication Transport Layer Security).","description":"The Simple Mail Transfer Protocol (SMTP) connector is used by Exchange to send and receive messages from server to server. Several controls work together to provide security between internal servers. This setting controls the authentication method used for communications between servers. With this feature enabled, only servers capable of supporting domain authentication will be able to send and receive mail within the domain.\n\nThe use of secure communication prevents eavesdroppers from reading or modifying communications between mail clients and servers. While sensitive message bodies should be encrypted by the sender at the client, requiring a secure connection from server to server adds protection by encrypting the sender and recipient information that cannot be encrypted by the sender. \n\nIndividually, channel security and encryption can be compromised by attackers. Used together, email becomes a more difficult target, and security is heightened. Failure to enable this feature gives eavesdroppers an opportunity to read or modify messages between servers.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-SendConnector | Select-Object -Property Name, Identity, DomainSecureEnabled\n\nFor each send connector, if the value of \"DomainSecureEnabled\" is not set to \"True\", this is a finding.\n\nIf the \"TlsAuthLevel\" parameter is set to \"DomainValidation\" then the \"TlsDomain\" parameter is required if \"DNSRoutingEnabled\" parameter is set to \"$false\".\n\nThe \"DNSRoutingEnabled\" parameter must be \"$true\" If the value of \"DomainSecureEnabled\" is \"$true\".","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-SendConnector <'IdentityName'> -DomainSecureEnabled $true\n\nNote: The value must be in quotes.\n\nRepeat the procedure for each send connector.","ccis":["CCI-001184"]},{"vulnId":"V-259595","ruleId":"SV-259595r1043178_rule","severity":"medium","ruleTitle":"Exchange internet-facing receive connectors must offer Transport Layer Security (TLS) before using basic authentication.","description":"Sending unencrypted email over the internet increases the risk that messages can be intercepted or altered. TLS is designed to protect confidentiality and data integrity by encrypting email messages between servers and thereby reducing the risk of eavesdropping, interception, and alteration. This setting forces Exchange to offer TLS before using basic authentication.","checkContent":"Note: This is not applicable for SIPR enclaves.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity, AuthMechanism\n\nFor each receive connector, if the value of \"AuthMechanism\" is not set to \"Tls, BasicAuth, BasicAuthRequireTLS\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -AuthMechanism 'Tls, BasicAuth, BasicAuthRequireTLS'\n\nNote: The value must be in quotes.\n\nExample only for the Identity: \\Frontend \n\nRepeat the procedure for each receive connector.","ccis":["CCI-001184"]},{"vulnId":"V-259596","ruleId":"SV-259596r961152_rule","severity":"medium","ruleTitle":"More than one Edge server must be deployed.","description":"To ensure hostile insiders are unable to easily commit DoS attacks and reduce the effectiveness of mail flow throughout the environment, a second Edge server is deployed to allow for multiple paths of mail flow both internally and externally into the environment. This prevents a single point-of-failure and allows for service to continue in the event of a DoS attack targeting one Edge role.","checkContent":"Review the EDSP for current configuration.\n\nOn the mailbox server, open a PowerShell prompt and run the following command:\n\nGet-EdgeSubscription\n\nIf there is only one subscription on each server, this is a finding.","fixText":"At a minimum, a second server must be deployed and subscribed to.","ccis":["CCI-001094"]},{"vulnId":"V-259597","ruleId":"SV-259597r961155_rule","severity":"medium","ruleTitle":"Exchange Outbound Connection Timeout must be 10 minutes or less.","description":"Email system availability depends in part on best practice strategies for setting tuning configurations. This configuration controls the number of idle minutes before the connection is dropped. It works in conjunction with the Maximum Outbound Connections Count setting.\n\nConnections, once established, may incur delays in message transfer. The default of 10 minutes is a reasonable window in which to resume activities without maintaining idle connections for excessive intervals. If the timeout period is too long, idle connections may be maintained for unnecessarily long time periods, preventing new connections from being established. Sluggish connectivity increases the risk of lost data. A value of 10 or less is optimal.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the Connection Timeout value.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-SendConnector | Select-Object -Property Name, Identity, ConnectionInactivityTimeOut\n\nFor each send connector, if the value of \"ConnectionInactivityTimeOut\" is not set to \"00:10:00\", this is a finding.\n\nor\n\nIf \"ConnectionInactivityTimeOut\" is set to other than \"00:10:00\" and has signoff and risk acceptance in the EDSP, this is not a finding.","fixText":"Update the EDSP to reflect the Connection Timeout value.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-SendConnector -Identity <'IdentityName'> -ConnectionInactivityTimeOut 00:10:00\n\nNote: The value must be in quotes.\n\nor\n\nThe value as identified by the EDSP that has obtained a signoff with risk acceptance.\n\nRepeat the procedure for each send connector.","ccis":["CCI-001095"]},{"vulnId":"V-259598","ruleId":"SV-259598r961155_rule","severity":"medium","ruleTitle":"Exchange Outbound Connection limit per Domain Count must be controlled.","description":"Email system availability depends in part on best practice strategies for setting tuning configurations. This configuration controls the maximum number of simultaneous outbound connections from a domain and works in conjunction with the Maximum Outbound Connections Count setting as a delivery tuning mechanism. If the limit is too low, connections may be dropped. If the limit is too high, some domains may use a disproportionate resource share, denying access to other domains. Appropriate tuning reduces the risk of data delay or loss.\n\nBy default, a limit of 20 simultaneous outbound connections from a domain should be sufficient. The value may be adjusted if justified by local site conditions.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the value for Maximum Domain Connections.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-TransportService | Select-Object -Property Name, Identity, MaxPerDomainOutboundConnections\n\nIf the value of \"MaxPerDomainOutboundConnections\" is not set to \"20\", this is a finding.\n\nor\n\nIf the value of \"MaxPerDomainOutboundConnections\" is set to a value other than \"20\" and has signoff and risk acceptance in the EDSP, this is not a finding.","fixText":"Update the EDSP to reflect the value for Maximum Domain Connections.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-TransportService -Identity <'IdentityName'> -MaxPerDomainOutboundConnections 20\n\nNote: The value must be in quotes.\n\nor\n\nThe value as identified by the EDSP that has obtained a signoff with risk acceptance.","ccis":["CCI-001095"]},{"vulnId":"V-259599","ruleId":"SV-259599r961155_rule","severity":"medium","ruleTitle":"Exchange receive connector maximum hop count must be 60.","description":"Email system availability depends in part on best practice strategies for setting tuning configurations. This setting controls the maximum number of hops (email servers traversed) a message may take as it travels to its destination. Part of the original internet protocol implementation, the hop count limit prevents a message from being passed in a routing loop indefinitely. Messages exceeding the maximum hop count are discarded undelivered. \n\nRecent studies indicate that virtually all messages can be delivered in fewer than 60 hops. If the hop count is set too low, messages may expire before they reach their destinations. If set too high, an undeliverable message may cycle between servers, raising the risk of network congestion.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the value for receive connectors.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity, MaxHopCount\n\nFor each receive connector, if the value of \"MaxHopCount\" is not set to \"60\", this is a finding. \n\nor \n\nIf the value of \"MaxHopCount\" is set to a value other than \"60\" and has signoff and risk acceptance, this is not a finding.","fixText":"Update the EDSP to reflect the value for receive connectors.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -MaxHopCount 60\n\nNote: The value must be in quotes.\n\nor\n\nThe value as identified by the EDSP that has obtained a signoff with risk acceptance.\n\nRepeat the procedure for each receive connector.","ccis":["CCI-001095"]},{"vulnId":"V-259600","ruleId":"SV-259600r961155_rule","severity":"medium","ruleTitle":"Exchange receive connectors must control the number of recipients per message.","description":"Email system availability depends in part on best practice strategies for setting tuning configurations. \n\nThis configuration controls the maximum number of recipients who will receive a copy of a message at one time. This tunable value is related to throughput capacity and can enable the ability to optimize message delivery. \n\nNote: There are two types of default receive connecters:\n\n\"Client Servername\" accepts SMTP connections from all non-MAPI clients, such as POP and IMAP. As POP and IMAP are not authorized for use in DOD, these should not be present. Their default value for MaxRecipientsPerMessage is 200. IMAP Secure is not restricted and may be configured.\n\n\"Default Servername\" accepts connections from other mailbox servers and any Edge Transport servers. Their default value for MaxRecipientsPerMessage is 5000.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the Maximum Recipients per Message value.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity, MaxRecipientsPerMessage\n\nFor each receive connector, if the value of \"MaxRecipientsPerMessage\" is not set to \"5000\", this is a finding.\n\nor\n\nIf the value of \"MaxRecipientsPerMessage\" is set to a value other than \"5000\" and has signoff and risk acceptance in the EDSP, this is not a finding.","fixText":"Update the EDSP to reflect the Maximum Recipients per Message value.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -MaxRecipientsPerMessage 5000 \n\nNote: The value must be in quotes.\n\nor \n\nThe value as identified by the EDSP that has obtained a signoff with risk acceptance.\n\nRepeat the procedure for each receive connector.","ccis":["CCI-001095"]},{"vulnId":"V-259601","ruleId":"SV-259601r961155_rule","severity":"medium","ruleTitle":"Exchange send connector connections count must be limited.","description":"This setting controls the maximum number of simultaneous outbound connections allowed for a given SMTP Connector and can be used to throttle the SMTP service if resource constraints warrant it. If the limit is too low, connections may be dropped. If the limit is too high, some domains may use a disproportionate resource share, denying access to other domains. Appropriate tuning reduces the risk of data delay or loss.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the value for SMTP Server Maximum Outbound Connections.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-TransportService | Select-Object -Property Name, Identity, MaxOutboundConnections\n\nIf the value of \"MaxOutboundConnections\" is not set to \"1000\", this is a finding.\n\nor\n\nIf the value of \"MaxOutboundConnections\" is set to a value other than \"1000\" and has signoff and risk acceptance in the EDSP, this is not a finding.","fixText":"Update the EDSP to reflect the value for SMTP Server Maximum Outbound Connections.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-TransportService -Identity <'IdentityName'> -MaxOutboundConnections 1000\n\nNote: The value must be in quotes.\n\nor\n\nThe value as identified by the EDSP that has obtained a signoff with risk acceptance.","ccis":["CCI-001095"]},{"vulnId":"V-259602","ruleId":"SV-259602r961155_rule","severity":"medium","ruleTitle":"Exchange message size restrictions must be controlled on Send connectors.","description":"Email system availability depends in part on best practice strategies for setting tuning configurations. For message size restrictions, multiple places exist to set or override inbound or outbound message size. Failure to control the configuration strategy can result in loss of data or system availability. \n\nThis setting enables the administrator to control the maximum message size on a Send connector. Using connectors to control size limits may necessitate applying message size limitations in multiple places, with the potential of introducing conflicts and impediments in the mail flow. Changing this setting at the connector overrides the global one. Therefore, if operational needs require it, the connector value may be set lower than the global value with the rationale documented in the EDSP.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the maximum message send size.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-SendConnector | Select-Object -Property Name, Identity, MaxMessageSize\n\nFor each send connector, if the value of \"MaxMessageSize\" is not the same as the global value, this is a finding.\n\nor\n\nIf \"MaxMessageSize\" is set to a numeric value different from the maximum message send size value documented in the EDSP, this is a finding.","fixText":"Update the EDSP to reflect the maximum message send size.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-SendConnector -Identity <'IdentityName'> -MaxMessageSize \n\nNote: The value must be in quotes.\n\nor\n\nThe value as identified by the EDSP that has obtained a signoff with risk acceptance.\n\nRepeat the procedure for each send connector.","ccis":["CCI-001095"]},{"vulnId":"V-259603","ruleId":"SV-259603r961155_rule","severity":"medium","ruleTitle":"Exchange send connectors delivery retries must be controlled.","description":"This setting controls the rate at which delivery attempts from the home domain are retried and user notifications are issued and notes the expiration time when the message will be discarded. \n\nIf delivery retry attempts are too frequent, servers will generate network congestion. If they are too far apart, messages may remain queued longer than necessary, potentially raising disk resource requirements.\n\nThe default values of these fields should be adequate for most environments. Administrators may wish to modify the values, but changes should be documented in the System Security Plan.\n\nNote: Transport configuration settings apply to the organization/global level of the Exchange SMTP path. By checking and setting them at the Hub server, the setting will apply to both Hub and Edge roles.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the value for Transient Failure Retry Count.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-TransportService | Select-Object -Property Name, Identity, TransientFailureRetryCount\n\nIf the value of \"TransientFailureRetryCount\" is not set to \"10\" or less, this is a finding.\n\nor\n\nIf the value of \"TransientFailureRetryCount\" is set to more than \"10\" or has signoff and risk acceptance in the EDSP, this is not a finding.","fixText":"Update the EDSP to reflect the value for Transient Failure Retry Count.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-TransportService -Identity <'IdentityName'> -TransientFailureRetryCount 10\n\nNote: The value must be in quotes.\n\nor\n\nThe value as identified by the EDSP that has obtained a signoff with risk acceptance.","ccis":["CCI-001095"]},{"vulnId":"V-259604","ruleId":"SV-259604r961155_rule","severity":"medium","ruleTitle":"Exchange receive connectors must be clearly named.","description":"For receive connectors, unclear naming as to direction and purpose increases risk that messages may not flow as intended, troubleshooting efforts may be impaired, or incorrect assumptions may be made about the completeness of the configuration. \n\nCollectively, connectors should account for all connections required for the overall email topology design. Simple Mail Transfer Protocol (SMTP) connectors, when listed, must name purpose and direction clearly, and their counterparts on servers to which they connect should be recognizable as their partners.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity\n\nFor each receive connector, review the naming for connectors.\n\nIf the connectors are not clearly named for purpose and direction, this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Name <'NewName'> -Identity <'IdentityName'>\n\nNote: Both the and value must be in quotes.\n\nRepeat the procedure for each receive connector.","ccis":["CCI-001095"]},{"vulnId":"V-259605","ruleId":"SV-259605r961155_rule","severity":"medium","ruleTitle":"Exchange receive connectors must control the number of recipients chunked on a single message.","description":"Email system availability depends in part on best practice strategies for setting tuning configurations. For message size restrictions, multiple places exist to set or override inbound or outbound message size. Failure to control the configuration strategy can result in loss of data or system availability.\n\nThis setting enables the administrator to enable \"chunking\" on received messages as they arrive at the domain. This is done so large message bodies can be relayed by the remote sender to the Receive connector in multiple, smaller chunks.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity, ChunkingEnabled\n\nFor each receive connector, if the value of \"ChunkingEnabled\" is not set to \"True\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -ChunkingEnabled $true\n\nNote: The value must be in quotes.\n\nRepeat the procedure for each receive connector.","ccis":["CCI-001095"]},{"vulnId":"V-259606","ruleId":"SV-259606r961155_rule","severity":"medium","ruleTitle":"The Exchange internet receive connector connections count must be set to default.","description":"Email system availability depends in part on best practice strategies for setting tuning configurations. This configuration controls the maximum number of simultaneous inbound connections allowed to the SMTP server. \n\nBy default, the number of simultaneous inbound connections is 5000. If a limit is set too low, the connections pool may be filled. If attackers perceive the limit is too low, they could deny service to the Simple Mail Transfer Protocol (SMTP) server by using a connection count that exceeds the limit set. By setting the default configuration to 5000, attackers would need many more connections to cause denial of service.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the Maximum Inbound connections value. \n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity, MaxInboundConnection\n\nIdentify internet-facing connectors.\n\nFor each receive connector, if the value of \"MaxInboundConnection\" is not set to \"5000\", this is a finding.\n\nor\n\nIf \"MaxInboundConnection\" is set to a value other than \"5000\" or is set to unlimited and has signoff and risk acceptance in the EDSP, this is not a finding.","fixText":"Update the EDSP to reflect the Maximum Inbound connections value.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -MaxInboundConnection 5000\n\nNote: The value must be in quotes.\n\nor\n\nThe value as identified by the EDSP that has obtained a signoff with risk acceptance.\n\nRepeat the procedure for each receive connector.","ccis":["CCI-001095"]},{"vulnId":"V-259607","ruleId":"SV-259607r961155_rule","severity":"medium","ruleTitle":"Exchange Message size restrictions must be controlled on receive connectors.","description":"Email system availability depends in part on best practices strategies for setting tuning configurations. For message size restrictions, multiple places exist to set or override inbound or outbound message size. Failure to control the configuration strategy can result in loss of data or system availability. \n\nThis setting enables the administrator to control the maximum message size on receive connectors. Using connectors to control size limits may necessitate applying message size limitations in multiple places, with the potential of introducing conflicts and impediments in the mail flow. Changing this setting at the connector overrides the global one. Therefore, if operational needs require it, the connector value may be set lower than the global value with the rationale documented in the EDSP.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the global maximum message receive size.\n\nOpen the Exchange Management Shell and enter the following command:\n\nIdentify internet-facing connectors.\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity, MaxMessageSize\n\nIf the value of \"MaxMessageSize\" is not the same as the global value, this is a finding.\n\nor\n\nIf \"MaxMessageSize\" is set to a numeric value different from the global value and has signoff and risk acceptance in the EDSP, this is not a finding.","fixText":"Update the EDSP to reflect the global maximum message receive size.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -MaxMessageSize <'MaxReceiveSize'>\n\nNote: The and values must be in quotes.\n\nor \n\nThe value as identified by the EDSP that has obtained a signoff with risk acceptance.","ccis":["CCI-001095"]},{"vulnId":"V-259608","ruleId":"SV-259608r961161_rule","severity":"medium","ruleTitle":"Active hyperlinks in messages from non .mil domains must be rendered unclickable.","description":"Active hyperlinks within an email are susceptible to attacks of malicious software or malware. The hyperlink could lead to a malware infection or redirect the website to another fraudulent website without the user's consent or knowledge.\n\nExchange does not have a built-in message filtering capability. DOD Enterprise Email (DEE) has created a custom resolution to filter messages from non-.mil users that have hyperlinks in the message body. The hyperlink within the messages will be modified, preventing end users from automatically clicking links.","checkContent":"Note: If using another DOD-approved anti-spam product for email or a DOD-approved Email Gateway spamming device, such as Enterprise Email Security Gateway (EEMSG), this is not applicable.\n\nNote: If system is on SIPRNet, this is not applicable.\n\nReview the Email Domain Security Plan (EDSP).\n\nDetermine the name of the Transport Agent. \n\nOpen the Windows PowerShell console and enter the following command:\n\nGet-TransportAgent -Name 'customAgent' | Format-List\n\nIf the value does not return \"customAgent\", this is a finding.\n\nNote: \"customAgent\" is the name of the custom agent developed to render hyperlink email sources from non .mil domains as unclickable.","fixText":"Update the EDSP to reflect the name of the Transport Agent.\n\nContact the DISA Enterprise Email Service Desk at disa.tinker.eis.mbx.dod-enterprise-services-service-desk@mail.mil and request the Agent and installation procedures.\n\nor\n\nContact DEE Engineering PMO and request the Agent and installation procedures.","ccis":["CCI-001308"]},{"vulnId":"V-259609","ruleId":"SV-259609r961161_rule","severity":"medium","ruleTitle":"Exchange messages with a blank sender field must be rejected.","description":"By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. Anonymous email (messages with blank sender fields) cannot be replied to. Messages formatted in this way may be attempting to hide their true origin to avoid responses or to spam any receiver with impunity while hiding their source of origination.\n\nRather than spend resources and risk infection while evaluating them, it is recommended that these messages be filtered immediately upon receipt and not forwarded to end users.","checkContent":"This requirement is Not Applicable for SIPR enclaves.\n\nThis requirement is Not Applicable if the organization subscribes to EEMSG or other similar DOD enterprise protections for email services.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-SenderFilterConfig | Select-Object -Property Name, Action \n\nIf the value of \"Action\" is not set to \"Reject\", this is a finding.\n\nNote: \"Reject\" is the default value.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-SenderFilterConfig -Action Reject","ccis":["CCI-001308"]},{"vulnId":"V-259610","ruleId":"SV-259610r961161_rule","severity":"medium","ruleTitle":"Exchange messages with a blank sender field must be filtered.","description":"By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. Anonymous email (messages with blank sender fields) cannot be replied to. Messages formatted in this way may be attempting to hide their true origin to avoid responses or to spam any receiver with impunity while hiding their source of origination. \n\nRather than spend resources and risk infection while evaluating them, it is recommended that these messages be filtered immediately upon receipt and not forwarded to end users.","checkContent":"This requirement is Not Applicable for SIPR enclaves. \n\nThis requirement is Not Applicable if the organization subscribes to EEMSG or other similar DOD enterprise protections for email services.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-SenderFilterConfig | Select-Object -Property Name, BlankSenderBlockingEnabled\n\nIf the value of \"BlankSenderBlockingEnabled\" is not set to \"True\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-SenderFilterConfig -BlankSenderBlockingEnabled $true","ccis":["CCI-001308"]},{"vulnId":"V-259611","ruleId":"SV-259611r961161_rule","severity":"medium","ruleTitle":"Exchange filtered messages must be archived.","description":"By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. This significantly reduces the attack vector for inbound email-borne spam and malware.\n\nAs messages are filtered, it is prudent to temporarily host them in an archive for evaluation by administrators or users. The archive can be used to recover messages that might have been inappropriately filtered, preventing data loss, and to provide a base of analysis that can provide future filter refinements.","checkContent":"Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-ContentFilterConfig | Select-Object -Property Name, quarantineMailbox\n\nIf no SMTP address is assigned to \"quarantineMailbox\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ContentFilterConfig -quarantineMailbox <'quarantineMailbox SmtpAddress'>\n\nNote: The value must be in quotes.","ccis":["CCI-001308"]},{"vulnId":"V-259612","ruleId":"SV-259612r961161_rule","severity":"medium","ruleTitle":"The Exchange sender filter must block unaccepted domains.","description":"Spam origination sites and other sources of suspected email-borne malware have the ability to corrupt, compromise, or otherwise limit availability of email servers. Limiting exposure to unfiltered inbound messages can reduce the risk of spam and malware impacts.\n\nThe Global Deny list blocks messages originating from specific sources. Most block list filtering is done using a commercial block list service, because eliminating threats from known spammers prevents the messages being evaluated inside the enclave where there is more risk they can do harm.\n\nAdditional sources should also be blocked to supplement the contents of the commercial Block List service. For example, during a zero-day threat action, entries can be added and then removed when the threat is mitigated. An additional best practice is to enter the enterprise's home domains in the block list, because inbound email with a \"from\" address of the home domain is very likely to be spoofed spam.","checkContent":"Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement.\n\nReview the Email Domain Security Plan (EDSP).\n\nDetermine the unaccepted domains that are to be blocked.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-SenderFilterConfig | Select-Object -Property Name, BlockedDomains, BlockedDomainsAndSubdomains\n\nIf the value for \"BlockedDomains\" or \"BlockedDomainsAndSubdomains\" does not reflect the list of accepted domains, this is a finding.","fixText":"Update the EDSP to reflect the unaccepted domains that are to be blocked.\n\nOpen the Exchange Management Shell and enter the following command:\n\nFor BlockedDomains:\n\nSet-SenderFilterConfig -BlockedDomains \n\nTo add additional domains to the list (array):\n\nSet-SenderFilterConfig -BlockedDomains @{add=\"\",\"\",\"\"}\n\nEach domain added must be quotes and separated by a comma.\n\nRepeat the procedure for each domain that is to be blocked.\n\nor\n\nFor BlockedDomainsAndSubdomains:\n\nSet-SenderFilterConfig -BlockedDomainsAndSubdomains \n\nSame procedure applies for adding multiple domains applies to this filter.\n\nRepeat the procedure for each domain and all of its subdomains that are to be blocked.","ccis":["CCI-001308"]},{"vulnId":"V-259613","ruleId":"SV-259613r961161_rule","severity":"medium","ruleTitle":"Exchange nonexistent recipients must not be blocked.","description":"Spam originators, in an effort to refine mailing lists, sometimes use a technique where they first create fictitious names and then monitor rejected emails for nonexistent recipients. Those not rejected are deemed to exist and are used in future spam mailings.\n\nTo prevent this disclosure of existing email accounts to spammers, email to nonexistent recipients must not be blocked. Instead, it is recommended that all messages be received, then evaluated and disposed of without enabling the sender to determine existent versus nonexistent recipients.","checkContent":"Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement.\n\nAdditionally, the default value for \"RecipientValidationEnabled\" is \"False\".\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-RecipientFilterConfig | Select-Object -Property Name, RecipientValidationEnabled\n\nIf the value of \"RecipientValidationEnabled\" is not set to \"False\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-RecipientFilterConfig -RecipientValidationEnabled $false","ccis":["CCI-001308"]},{"vulnId":"V-259614","ruleId":"SV-259614r961161_rule","severity":"medium","ruleTitle":"The Exchange Sender Reputation filter must be enabled.","description":"By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. Sender Reputation is anti-spam functionality that blocks messages according to many characteristics of the sender. Sender Reputation relies on persisted data about the sender to determine what action, if any, to take on an inbound message. This setting enables the Sender Reputation function.","checkContent":"Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement.\n\nAdditionally, the default value for \"Sender Reputation\" is \"True\" for \"Enabled\".\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-SenderReputationConfig | Select-Object -Property Name, Enabled\n\nIf the value of \"Enabled\" is not set to \"True\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-SenderReputationConfig -Enabled $true","ccis":["CCI-001308"]},{"vulnId":"V-259615","ruleId":"SV-259615r961161_rule","severity":"medium","ruleTitle":"The Exchange Sender Reputation filter must identify the spam block level.","description":"By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. Sender Reputation is anti-spam functionality that blocks messages according to many characteristics of the sender. Sender Reputation relies on persisted data about the sender to determine what action, if any, to take on an inbound message. This setting enables the threshold at which an email will be considered spam.","checkContent":"Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement.\n\nReview the Email Domain Security Plan (EDSP).\n\nDetermine the SrlBlockThreshold value.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-SenderReputationConfig | Select-Object -Property Name, SrlBlockThreshold\n\nIf the value of SrlBlockThreshold is not set to \"6\", this is a finding.\n\nor\n\nIf the value of \"SrlBlockThreshold\" is set to a value other than \"6\" and has signoff and risk acceptance in the EDSP, this is not a finding.","fixText":"Update the EDSP to reflect the SrlBlockThreshold size. \n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-SenderReputationConfig -SrlBlockThreshold 6\n\nor\n\nThe value as identified by the EDSP that has obtained a signoff with risk acceptance.","ccis":["CCI-001308"]},{"vulnId":"V-259616","ruleId":"SV-259616r961161_rule","severity":"medium","ruleTitle":"Exchange Attachment filtering must remove undesirable attachments by file type.","description":"By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment.\n\nAttachments are being used more frequently for different forms of attacks. By filtering undesirable attachments, a large percent of malicious code can be prevented from entering the system. Attachments must be controlled at the entry point into the email environment to prevent successful attachment-based attacks. The following is a basic list of known attachments that should be filtered from internet mail attachments:\n\n*.ade *.crt *.jse *.msi *.scr *.wsh *.dir\n*.adp *.csh *.ksh *.msp *.sct *.htm *.dcr\n*.app *.exe *.lnk *.mst *.shb *.html *.plg\n*.asx *.fxp *.mda *.ops *.shs *.htc *.spl\n*.bas *.hlp *.mdb *.pcd *.url *.mht *.swf\n*.bat *.hta *.mde *.pif *.vb *.mhtml *.zip\n*.chm *.inf *.mdt *.prf *.vbe *.shtm \n*.cmd *.ins *.mdw *.prg *.vbs *.shtml \n*.com *.isp *.mdz *.reg *.wsc *.stm \n*.cpl *.js *.msc *.scf *.wsf *.xml","checkContent":"Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement.\n\nReview the Email Domain Security Plan (EDSP).\n\nDetermine the list of undesirable attachment types that should be stripped.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-AttachmentFilterEntry \n\nFor each attachment type, if the values returned are different from the EDSP documented attachment types, this is a finding.","fixText":"Update the EDSP to reflect the list of undesirable attachment types that should be stripped.\n\nOpen the Exchange Management Shell and enter the following command:\n\nAdd-AttachmentFilterEntry -Name <'*.FileExtension'> -Type FileName\n\nRepeat the procedure for each undesirable attachment type.","ccis":["CCI-001308"]},{"vulnId":"V-259617","ruleId":"SV-259617r961161_rule","severity":"medium","ruleTitle":"The Exchange Spam Evaluation filter must be enabled.","description":"By performing filtering at the perimeter, up to 90 percent of spam, malware, and other undesirable messages may be eliminated from the transport message stream, preventing their entry into the Exchange environment. This significantly reduces the attack vector for inbound email-borne spam and malware.\n\nSpam Evaluation filters scan inbound email messages for evidence of spam and other attacks that primarily use social engineering techniques. Upon evaluation completion, a rating is assigned to each message estimating the likelihood of its being spam. Upon arrival at the destination mailbox, the junk mail filter threshold (also configurable) determines whether the message will be withheld from delivery, delivered to the junk mail folder, or delivered to the user's inbox.","checkContent":"Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement. Additionally, the default value for this property is Enabled \"True\".\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-ContentFilterConfig | Select-Object -Property Name, Identity, Enabled\n\nIf the value of \"Enabled\" is not set to \"True\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ContentFilterConfig -Enabled $true","ccis":["CCI-001308"]},{"vulnId":"V-259618","ruleId":"SV-259618r961161_rule","severity":"medium","ruleTitle":"The Exchange Block List service provider must be identified.","description":"Block List filtering is a sanitization process performed on email messages prior to their arrival at the destination mailbox. By performing this process at the email perimeter, threats can be eliminated outside the enclave, where there is less risk for them to do harm.\n\nBlock List services (sometimes called Reputation Data services) are fee-based data providers that collect the IP addresses of known spammers and other malware purveyors. Block List service subscribers benefit from more effective spam elimination. (Spam is estimated to compose up to 90 percent of inbound mail volume.) Failure to specify a Block List provider risks that manual email administration effort would be needed to maintain and update larger Block Lists than a single email site administrator could conveniently or accurately maintain.\n\nThe Block List service vendor provides a value for this field, usually the Domain Name System (DNS) suffix for its domain.","checkContent":"If not using a service provider, this requirement is not applicable. \n\nReview the Email Domain Security Plan (EDSP).\n\nDetermine the name and information for the Block List provider. \n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-IPBlockListProvider | Select-Object -Property Name, Identity, LookupDomain\n\nIf the values for \"Name\", GUID, and \"LookupDomain\" are not configured, this is a finding.","fixText":"Update the EDSP to reflect the name and information for the Block List provider.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-IPBlockListProvider -Name [Additional optional parameters as required by the service provider]","ccis":["CCI-001308"]},{"vulnId":"V-259619","ruleId":"SV-259619r1040909_rule","severity":"medium","ruleTitle":"Exchange messages with a malformed From address must be rejected.","description":"Sender Identification (SID) is an email anti-spam sanitization process. Sender ID uses DNS MX record lookups to verify the Simple Mail Transfer Protocol (SMTP) sending server is authorized to send email for the originating domain.\n\nFailure to implement Sender ID risks that spam could be admitted into the email domain that originates from rogue servers. Most spam content originates from domains where the IP address has been spoofed prior to sending, thereby avoiding detection. For example, messages with malformed or incorrect \"purported responsible sender\" data in the message header could be (best case) created by using RFI noncompliant software but is more likely to be spam.","checkContent":"If this server is in a SIPR Enclave, this requirement is Not Applicable.\n\nNote: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-SenderIdConfig | Select-Object -Property Name, Identity, SpoofedDomainAction\n\nIf the value of \"SpoofedDomainAction\" is not set to \"Reject\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-SenderIdConfig -SpoofedDomainAction Reject","ccis":["CCI-001308"]},{"vulnId":"V-259620","ruleId":"SV-259620r961161_rule","severity":"medium","ruleTitle":"The Exchange Recipient filter must be enabled.","description":"Email system availability depends in part on best practice strategies for setting tuning configurations. Careful tuning reduces the risk that system or network congestion will contribute to availability impacts.\n\nFilters that govern inbound email evaluation can significantly reduce spam, phishing, and spoofed emails. Messages from blank senders, known spammers, or zero-day attack modifications must be enabled to be effective.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-RecipientFilterConfig | Select-Object -Property Name, Enabled\n\nIf the value of \"Enabled\" is not set to \"True\", this is a finding.\n\nNote: The default value is set to \"True\".","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-RecipientFilterConfig -Enabled $true","ccis":["CCI-001308"]},{"vulnId":"V-259621","ruleId":"SV-259621r961161_rule","severity":"medium","ruleTitle":"The Exchange tarpitting interval must be set.","description":"Tarpitting is the practice of artificially delaying server responses for specific Simple Mail Transfer Protocol (SMTP) communication patterns that indicate high volumes of spam or other unwelcome messages. The intent of tarpitting is to slow down the communication process for spam batches to reduce the cost effectiveness of sending spam and thwart directory harvest attacks.\n\nA directory harvest attack is an attempt to collect valid email addresses from a particular organization so the email addresses can be added to a spam database. A program can be written to collect email addresses that return a \"Recipient OK\" SMTP response and discard all email addresses that return a \"User unknown\" SMTP response.\n\nTarpitting makes directory harvest attacks too costly to automate efficiently.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select Name, Identity, TarpitInterval\n\nFor each Receive connector, if the value of \"TarpitInterval\" is not set to \"00:00:05\" or greater, this is a finding.\n\nNote: The default value for \"TarpitInterval\" is \"00:00:05\".","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -TarpitInterval '00:00:05'\n\nNote: The value and the Interval must be in quotes.\n\nRepeat the procedures for each Receive connector.","ccis":["CCI-001308"]},{"vulnId":"V-259622","ruleId":"SV-259622r961161_rule","severity":"medium","ruleTitle":"Exchange internal Receive connectors must not allow anonymous connections.","description":"This control is used to limit the servers that may use this server as a relay. If a Simple Mail Transport Protocol (SMTP) sender does not have a direct connection to the internet (for example, an application that produces reports to be emailed), it will need to use an SMTP Receive connector that does have a path to the internet (for example, a local email server) as a relay.\n\nSMTP relay functions must be protected so third parties are not able to hijack a relay service for their own purposes. Most commonly, relay hijacking is done by spammers to disguise the source of their messages and may also be used to cover the source of more destructive attacks.\n\nRelays can be restricted in one of three ways: by blocking relays (restrict to a blank list of servers); by restricting use to lists of valid servers; or by restricting use to servers that can authenticate. Because authenticated connections are the most secure for SMTP Receive connectors, it is recommended that relays allow only servers that can authenticate.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity, PermissionGroups |Format-List\n\nFor each Receive connector, if the value of \"PermissionGroups\" is \"AnonymousUsers\" for any noninternet connector, this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -PermissionGroups 'valid user group(s)'\n\nNote: The value and user group(s) must be in quotes.\n\nExample for user groups only: 'ExchangeServers, ExchangeUsers' \n\nRepeat the procedures for each Receive connector.\n\nThis is an example only: Set-ReceiveConnector -Identity <'IdentityName'> -PermissionGroups 'ExchangeUsers'","ccis":["CCI-001308"]},{"vulnId":"V-259623","ruleId":"SV-259623r961161_rule","severity":"medium","ruleTitle":"Exchange Simple Mail Transfer Protocol (SMTP) IP Allow List entries must be empty.","description":"Email system availability depends in part on best practice strategies for setting tuning configurations. Careful tuning reduces the risk that system or network congestion will contribute to availability impacts.\n\nFilters that govern inbound email evaluation can significantly reduce spam, phishing, and spoofed emails. Filters for messages from blank senders, known spammers, or zero-day attack modifications must be enabled to be effective.\n\nHaving items identified in the Allow List causes other spam evaluation steps to be bypassed and therefore should be used only with an abundance of caution. If spammers were to learn of entries in the Allow List, it could enable them to plan a denial of service attack (or other attack) by spoofing that source.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nIdentify the SMTP Allow List settings.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-IPAllowListEntry | Format-List\n\nIf the result returns any values, this is a finding.\n\nor \n\nIf the result returns any values but has signoff and risk acceptance in the EDSP, this is not a finding.","fixText":"Update the EDSP to reflect the SMTP Allow List settings.\n\nOpen the Exchange Management Shell and enter the following command:\n\nNote: Remove any value(s) that are not identified by the EDSP or have not obtained a signoff with risk acceptance.\n\nRemove-IPAllowListEntry -Identity ","ccis":["CCI-001308"]},{"vulnId":"V-259624","ruleId":"SV-259624r961161_rule","severity":"medium","ruleTitle":"The Exchange Simple Mail Transfer Protocol (SMTP) IP Allow List Connection filter must be enabled.","description":"Email system availability depends in part on best practice strategies for setting tuning configurations. Careful tuning reduces the risk that system or network congestion will contribute to availability impacts.\n\nFilters that govern inbound email evaluation can significantly reduce spam, phishing, and spoofed emails. Filters for messages from blank senders, known spammers, or zero-day attack modifications must be enabled to be effective.\n\nHaving items identified in the Allow List causes other spam evaluation steps to be bypassed and therefore should be used only with an abundance of caution. If spammers were to learn of entries in the Allow List, it could enable them to plan a denial of service attack (or other attack) by spoofing that source.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-IPAllowListConfig | Select-Object -Property Name, Enabled\n\nIf the value for \"Enabled\" is not set to \"True\", this is a finding.\n\nNote: \"Enabled\" set to \"True\" is the default value.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-IPAllowListConfig -Enabled $true","ccis":["CCI-001308"]},{"vulnId":"V-259625","ruleId":"SV-259625r961161_rule","severity":"medium","ruleTitle":"The Exchange Simple Mail Transfer Protocol (SMTP) Sender filter must be enabled.","description":"Email system availability depends in part on best practices strategies for setting tuning configurations. Careful tuning reduces the risk that system or network congestion will contribute to availability impacts.\n\nFilters that govern inbound email evaluation can significantly reduce spam, phishing, and spoofed emails. Filters for messages from blank senders, known spammers, or zero-day attack modifications must be enabled to be effective.\n\nFailure to enable the filter will result in no action taken. This setting should always be enabled.","checkContent":"This requirement is not applicable for SIPR enclaves. \n\nThis requirement is not applicable if the organization subscribes to EEMSG or other similar DOD enterprise protections for email services.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-SenderFilterConfig | Select-Object -Property Name, Enabled\n\nIf the value of \"Enabled\" is not set to \"True\", this is a finding.\n\nNote: \"Enabled\" set to \"True\" is the default value.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-SenderFilterConfig -Enabled $true","ccis":["CCI-001308"]},{"vulnId":"V-259626","ruleId":"SV-259626r961161_rule","severity":"medium","ruleTitle":"Exchange must have anti-spam filtering installed.","description":"Originators of spam messages are constantly changing their techniques to defeat spam countermeasures; therefore, spam software must be constantly updated to address the changing threat. Spam protection mechanisms include, for example, signature definitions, rule sets, and algorithms.\n\nExchange 2019 provides both anti-spam and anti-malware protection out of the box. The Exchange 2019 anti-spam and anti-malware product capabilities are limited but still provide some protection.","checkContent":"Review the Email Domain Security Plan (EDSP) for an installed anti-spam product.\n\nNote: If using another DOD-approved anti-spam product for email or a DOD-approved Email Gateway spamming device, such as Enterprise Email Security Gateway (EEMSG), this is not applicable.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-ContentFilterConfig | Format-Table Name, Enabled \n\nIf no value is returned, this is a finding.","fixText":"Install the anti-Spam module.\n\nOpen the Exchange Management Shell and enter the following command:\n\n& $env:ExchangeInstallPath\\Scripts\\Install-anti-SpamAgents.ps1","ccis":["CCI-001308"]},{"vulnId":"V-259627","ruleId":"SV-259627r961161_rule","severity":"medium","ruleTitle":"Exchange must have anti-spam filtering enabled.","description":"Originators of spam messages are constantly changing their techniques to defeat spam countermeasures; therefore, spam software must be constantly updated to address the changing threat. Spam protection mechanisms include, for example, signature definitions, rule sets, and algorithms.\n\nExchange 2019 provides both anti-spam and anti-malware protection out of the box. The Exchange 2019 anti-spam and anti-malware product capabilities are limited but still provide some protection.","checkContent":"Review the Email Domain Security Plan (EDSP) for an installed anti-spam product.\n\nNote: If using another DOD-approved anti-spam product for email or a DOD-approved Email Gateway spamming device, such as Enterprise Email Security Gateway (EEMSG), this is not applicable.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-ContentFilterConfig | Format-Table Name, Enabled; Get-SenderFilterConfig | Format-Table Name, Enabled; Get-SenderIDConfig | Format-Table Name, Enabled; Get-SenderReputationConfig | Format-Table Name, Enabled\n\nIf any of the following values returned are not set to \"True\", this is a finding:\n\nSet-ContentFilterConfig \nSet-SenderFilterConfig \nSet-SenderIDConfig \nSet-SenderReputationConfig","fixText":"Open the Exchange Management Shell and enter the following command for any values that were not set to True:\n\nSet-ContentFilterConfig -Enabled $true\n\nSet-SenderFilterConfig -Enabled $true\n\nSet-SenderIDConfig -Enabled $true\n\nSet-SenderReputationConfig -Enabled $true","ccis":["CCI-001308"]},{"vulnId":"V-259628","ruleId":"SV-259628r961161_rule","severity":"medium","ruleTitle":"Exchange must have anti-spam filtering configured.","description":"Originators of spam messages are constantly changing their techniques to defeat spam countermeasures; therefore, spam software must be constantly updated to address the changing threat. A manual update procedure is labor intensive and does not scale well in an enterprise environment. This risk may be mitigated by using an automatic update capability. Spam protection mechanisms include, for example, signature definitions, rule sets, and algorithms.\n\nExchange 2019 provides both anti-spam and anti-malware protection out of the box. The Exchange 2019 anti-spam and anti-malware product capabilities are limited but still provide some protection.","checkContent":"The site should use an approved DOD scanner as Exchange Malware software has a limited scanning capability.\n\nIf an approved DOD scanner is not being used, this is a finding.","fixText":"Following vendor best practice guidance, install and configure a DOD approved scanner.","ccis":["CCI-001308"]},{"vulnId":"V-259629","ruleId":"SV-259629r961161_rule","severity":"medium","ruleTitle":"Exchange Sender Identification Framework must be enabled.","description":"Email is only as secure as the recipient. When the recipient is an email server accepting inbound messages, authenticating the sender enables the receiver to better assess message quality and to validate the sending domain as authentic. One or more authentication techniques used in combination can be effective in reducing spam, phishing, and forger attacks.\n\nThe Sender ID Framework (SIDF) receiver accesses specially formatted DNS records (SPF format) that contain the IP address of authorized sending servers for the sending domain that can be compared to data in the email message header. Receivers are able to validate the authenticity of the sending domain, helping to avoid receiving inbound messages from phishing or other spam domains.","checkContent":"Note: If third-party anti-spam product is being used, the anti-spam product must be configured to meet the requirement.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-SenderIdConfig | Select-Object -Property Name, Identity, Enabled\n\nIf the value of \"Enabled\" is not set to \"True\", this is a finding.\n\nNote: By Default, the value of \"Enabled\" is set to \"True\".","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-SenderIdConfig -Enable $true","ccis":["CCI-001308"]},{"vulnId":"V-259630","ruleId":"SV-259630r1043182_rule","severity":"medium","ruleTitle":"Exchange must limit the Receive connector timeout.","description":"Email system availability depends in part on best practices strategies for setting tuning. This configuration controls the number of idle minutes before the connection is dropped. It works in conjunction with the Maximum Inbound Connections Count setting.","checkContent":"Review the Email Domain Security Plan (EDSP), or Organizations applicable documentation.\n\nDetermine the connection Timeout value.\n\nOpen the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity, ConnectionTimeout\n\nFor each Receive connector, if the value of \"ConnectionTimeout\" is not set to \"00:05:00\", this is a finding.\n\nIf \"ConnectionTimeout\" is set to another value other than \"00:05:00\" and has signoff and risk acceptance in the EDSP, this is not a finding.","fixText":"Update the EDSP, or the applicable documentation.\n\nOpen the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -ConnectionTimeout 00:05:00\n\nNote: The value must be in quotes.\n\nor\n\nThe value as identified by the EDSP that has obtained a signoff with risk acceptance.\n\nRepeat the procedures for each Receive connector.","ccis":["CCI-002361"]},{"vulnId":"V-259631","ruleId":"SV-259631r961353_rule","severity":"medium","ruleTitle":"Role-Based Access Control must be defined for privileged and nonprivileged users.","description":"Role Based Access Control (RBAC) is the permissions model used in Microsoft Exchange Server 2013, 2016, and 2019. With RBAC, there is no need to modify and manage access control lists (ACLs), which was done in Exchange Server 2007. ACLs created several challenges in Exchange 2007, such as modifying ACLs without causing unintended consequences, maintaining ACL modifications through upgrades, and troubleshooting problems that occurred due to using ACLs in a nonstandard way.\n\nRBAC enables users to control, at both broad and granular levels, what administrators and end users can do. RBAC also enables users to more closely align the roles assigned to users and administrators to the actual roles they hold within the organization. In Exchange 2007, the server permissions model applied only to the administrators who managed the Exchange 2007 infrastructure. Starting in Exchange 2013, RBAC now controls both the administrative tasks that can be performed and the extent to which users can now administer their own mailbox and distribution groups.","checkContent":"Check the EDSP to verify who should be in each built in RBAC management role group.\n\nIf this is not found, this is a finding.","fixText":"Update the EDSP and define who should and should not have elevated privileges within the organization.\n\nFollow the rule of least privilege and ensure that administrators are given just enough access to complete their job.\n\nReference document: https://docs.microsoft.com/en-us/exchange/understanding-management-role-groups-exchange-2013-help?view=exchserver-2019","ccis":["CCI-002235"]},{"vulnId":"V-259632","ruleId":"SV-259632r1015763_rule","severity":"medium","ruleTitle":"The Exchange application directory must be protected from unauthorized access.","description":"Default product installations may provide more generous access permissions than are necessary to run the application. By examining and tailoring access permissions to provide the least amount of privilege possible more closely, attack vectors that align with user permissions are less likely to access more highly secured areas.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the authorized groups and users that have access to the Exchange application directories.\n\nDetermine if the access permissions on the directory match the access permissions listed in the EDSP.\n\nIf any group or user has different access permissions than listed in the EDSP, this is a finding.\n\nNote: The default installation directory is \\Program Files\\Microsoft\\Exchange Server\\V15.","fixText":"Update the EDSP to reflect the authorized groups and users that have access to the Exchange application directories.\n\nNavigate to the Exchange application directory and remove or modify the group or user access permissions.\n\nNote: The default installation directory is \\Program Files\\Microsoft\\Exchange Server\\V15.","ccis":["CCI-003980","CCI-001812"]},{"vulnId":"V-259633","ruleId":"SV-259633r961461_rule","severity":"medium","ruleTitle":"The Exchange software baseline copy must exist.","description":"Exchange software, as with other application software installed on a host system, must be included in a system baseline record and periodically reviewed; otherwise, unauthorized changes to the software may not be discovered. This effort is a vital step to securing the host and the applications, as it is the only method that may provide the ability to detect and recover from otherwise undetected changes, such as those that result from worm or bot intrusions.\n\nThe Exchange software and configuration baseline is created and maintained for comparison during scanning efforts. Operational procedures must include baseline updates as part of configuration management tasks that change the software and configuration.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the baseline documentation.\n\nReview the application software baseline procedures and implementation artifacts.\n\nNote the list of files and directories included in the baseline procedure for completeness.\n\nIf an email software copy exists to serve as a baseline and is available for comparison during scanning efforts, this is not a finding.","fixText":"Implement an email software baseline process and update the EDSP.","ccis":["CCI-001813"]},{"vulnId":"V-259634","ruleId":"SV-259634r1015764_rule","severity":"medium","ruleTitle":"The Exchange local machine policy must require signed scripts.","description":"Scripts, especially those downloaded from untrusted locations, often provide a way for attackers to infiltrate a system. By setting machine policy to prevent unauthorized script executions, unanticipated system impacts can be avoided.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ExecutionPolicy\n\nIf the value returned is not \"RemoteSigned\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ExecutionPolicy RemoteSigned","ccis":["CCI-003938","CCI-001814"]},{"vulnId":"V-259635","ruleId":"SV-259635r961470_rule","severity":"medium","ruleTitle":"Exchange services must be documented, and unnecessary services must be removed or disabled.","description":"Unneeded but running services offer attackers an enhanced attack profile, and attackers are constantly watching to discover open ports with running services. By analyzing and disabling unneeded services, the associated open ports become unresponsive to outside queries, and servers become more secure as a result.\n\nExchange Server has role-based server deployment to enable protocol path control and logical separation of network traffic types.\n\nFor example, a server implemented in the Client Access role (i.e., Outlook Web App [OWA]) is configured and tuned as a web server using web protocols. A client access server exposes only web protocols (HTTP/HTTPS), enabling system administrators to optimize the protocol path and disable all services unnecessary for Exchange web services.\n\nSimilarly, servers created to host mailboxes are dedicated to that task and must operate only the services needed for mailbox hosting. (Exchange servers must also operate some web services but only to the degree that Exchange requires the IIS engine in order to function).\n\nBecause POP3 and IMAP4 clients are not included in the standard desktop offering, they must be disabled.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nNote: Required services will vary between organizations and will vary depending on the role of the individual system. Organizations will develop their own list of services, which will be documented and justified with the ISSO. The site's list will be provided for any security review. Services that are common to multiple systems can be addressed in one document. Exceptions for individual systems should be identified separately by system.\n\nOpen a Windows PowerShell and enter the following command:\n\nGet-Service | Where-Object {$_.status -eq 'running'}\n\nNote: The command returns a list of installed services and the status of that service.\n\nIf the services required are not documented in the EDSP or undocumented or unnecessary services are running, this is a finding.","fixText":"Update the EDSP with the services required for the system to function.\n\nNavigate to Administrator Tools >> Services and disable or remove any services that are not required.\n\nor \n\nin PowerShell:\nStop-Service -Name ;\nSet-Service -Name -StartupType Disabled \nStop and disable services that are not required.","ccis":["CCI-001762"]},{"vulnId":"V-259636","ruleId":"SV-259636r961587_rule","severity":"medium","ruleTitle":"The Exchange Edge server must point to a trusted list of DNS servers for external and internal resolution.","description":"To mitigate the risk of possible erroneous queries that may have been coopted by bad actors, the Exchange Edge server must use DNS servers that utilize DNSSEC to resolve external hosts and internal hosts before routing messages to the appropriate destination.","checkContent":"Verify in the EDSP or consult with the appropriate personnel who manage DNS which servers to use for Internal and External DNS resolution. \n\nIf the server is not multi-homed, this does not apply.\n\nIn Exchange Management Shell, run the following command:\n\nGet-TransportService |Format-List *dns*\n\nIf \"ExternalDNSAdapterEnabled : True\", and no GUID exists, this is a finding.\n\nIf \"ExternalDNSAdapterEnabled : False\", and the property \"ExternalDNSServers\" is not populated with the documented trusted DNS servers for External DNS queries, this is a finding.\n\nIf \"InternalDNSAdapterEnabled : True\" and no GUID exists, this is a finding.\n\nIf \"InternalDNSAdapterEnabled : False\" and the property \"InternalDNSServers\" is not populated the documented trusted DNS servers for Internal DNS queries, this is a finding.","fixText":"Verify in the EDSP or consult with the appropriate personnel who manage which DNS servers to use for Internal and External DNS resolution.\n\nIf a GUID for the External and Internal network adapters are applicable, then gather the values to populate the appropriate properties with the following commands:\n\nnetsh lan show interfaces\n\nThis will provide the adapters and the GUIDs for each. Identify the external and internal adapters for the Edge server.\n\nOnce gathered, run the following:\n\nSet-TransportService -Identity -ExternalDNSAdapterEnabled $true -ExternalDNSAdapterGuid -InternalDNSAdapterEnabled $true -InternalDNSAdapterGuid \n\nIf the \"ExternalDNSAdapterEnabled\" or InternalDNSAdapterEnabled are set to false, use the following to set the DNS configuration:\n\nSet-TransportService -Identity -InternalDNSServers @{add=\"Trusted DNS IP1\",\"Trusted DNS IP2\"}\nSet-TransportService -Identity -ExternalDNSServers @{add=\"Trusted DNS IP1\",\"Trusted DNS IP2\"}","ccis":["CCI-002466"]},{"vulnId":"V-259637","ruleId":"SV-259637r961608_rule","severity":"medium","ruleTitle":"Exchange software must be installed on a separate partition from the OS.","description":"In the same way that added security layers can provide a cumulative positive effect on security posture, multiple applications can provide a cumulative negative effect. A vulnerability and subsequent exploit to one application can lead to an exploit of other applications sharing the same security context. For example, an exploit to a web server process that leads to unauthorized administrative access to the host system can most likely lead to a compromise of all applications hosted by the same system.\n\nEmail services should be installed on a partition that does not host other applications. Email services should never be installed on a Domain Controller/Directory Services server.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nDetermine the directory where Exchange is installed.\n\nOpen Windows Explorer. \n\nNavigate to the location where Exchange is installed.\n\nIf Exchange resides on a directory or partition other than that of the OS and does not have other applications installed (without associated approval from the ISSO), this is not a finding.","fixText":"Update the EDSP to reflect the directory where Exchange is installed.\n\nInstall Exchange on a dedicated application directory or partition separate than that of the OS.","ccis":["CCI-002530"]},{"vulnId":"V-259638","ruleId":"SV-259638r961620_rule","severity":"medium","ruleTitle":"The Exchange SMTP automated banner response must not reveal server details.","description":"Automated connection responses occur as a result of FTP or Telnet connections when connecting to those services. They report a successful connection by greeting the connecting client and stating the name, release level, and (often) additional information about the responding product. While useful to the connecting client, connection responses can also be used by a third party to determine operating system or product release levels on the target server. The result can include disclosure of configuration information to third parties, paving the way for possible future attacks. For example, when querying the SMTP service on port 25, the default response looks similar to this one: \n\n220 exchange.mydomain.org Microsoft ESMTP MAIL Service ready at Tuesday, 23 Nov 2021 13:43:00 -0500\n\nChanging the response to hide local configuration details reduces the attack profile of the target.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity, Banner\n\nIf the value of \"Banner\" is not set to \"220 SMTP Server Ready\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -Banner '220 SMTP Server Ready'\n\nNote: The and 220 SMTP Server Ready values must be in quotes.","ccis":["CCI-002385"]},{"vulnId":"V-259639","ruleId":"SV-259639r961620_rule","severity":"medium","ruleTitle":"Exchange internal Send connectors must use an authentication level.","description":"The Simple Mail Transfer Protocol (SMTP) connector is used by Exchange to send and receive messages from server to server. Several controls work together to provide security between internal servers. This setting controls the encryption method used for communications between servers. With this feature enabled, only servers capable of supporting Transport Layer Security (TLS) will be able to send and receive mail within the domain.\n\nThe use of secure communication prevents eavesdroppers from reading or modifying communications between mail clients and servers. While sensitive message bodies should be encrypted by the sender at the client, requiring a secure connection from server to server adds protection by encrypting the sender and recipient information that cannot be encrypted by the sender.\n\nIndividually, channel security and encryption can be compromised by attackers. Used together, email becomes a more difficult target, and security is heightened. Failure to enable this feature gives eavesdroppers an opportunity to read or modify messages between servers.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-SendConnector | Select-Object -Property Name, Identity, TlsAuthLevel\n\nIf the value of \"TlsAuthLevel\" is not set to \"DomainValidation\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-SendConnector -Identity <'IdentityName'> -TlsAuthLevel DomainValidation","ccis":["CCI-002385"]},{"vulnId":"V-259640","ruleId":"SV-259640r961632_rule","severity":"high","ruleTitle":"Exchange must provide redundancy.","description":"Denial of Service (DoS) is a condition when a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded capacity.\n\nThis requirement addresses the configuration of applications to mitigate the impact of DoS attacks that have occurred or are ongoing on application availability. For each application, known and potential DoS attacks must be identified and solutions for each type implemented. A variety of technologies exist to limit or, in some cases, eliminate the effects of DoS attacks (e.g., limiting processes or restricting the number of sessions the application opens at one time). Employing increased capacity and bandwidth, combined with service redundancy, may reduce the susceptibility to some DoS attacks.","checkContent":"Review the Email Domain Security Plan (EDSP).\n\nFrom a Mailbox server in the subscribed Edge Subscription site, determine if the Exchange servers are using redundancy by entering the following command:\n\nGet-EdgeSubscription\n\nIf the value returned is not at least two Edge servers, this is a finding.","fixText":"Update the EDSP to reflect the Exchange servers used for redundancy.\n\nConfigure and subscribe to two or more Edge servers for load balancing.","ccis":["CCI-002418"]},{"vulnId":"V-259641","ruleId":"SV-259641r961632_rule","severity":"high","ruleTitle":"Exchange internal Receive connectors must require encryption.","description":"The Simple Mail Transfer Protocol (SMTP) Receive connector is used by Exchange to send and receive messages from server to server using SMTP protocol. This setting controls the encryption strength used for client connections to the SMTP Receive connector. With this feature enabled, only clients capable of supporting secure communications will be able to send mail using this SMTP server. Where secure channels are required, encryption can also be selected.\n\nThe use of secure communication prevents eavesdroppers from reading or modifying communications between mail clients and servers. While sensitive message bodies should be encrypted by the sender at the client, requiring a secure connection from the client to the server adds protection by encrypting the sender and recipient information that cannot be encrypted by the sender.\n\nIndividually, channel security and encryption have been compromised by attackers. Used together, email becomes a more difficult target, and security is heightened. Failure to enable this feature gives eavesdroppers an opportunity to read or modify messages between the client and server.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ReceiveConnector | Select-Object -Property Name, Identity, AuthMechanism\n\nFor each Receive connector, if the value of \"AuthMechanism\" is not set to \"Tls\", this is a finding.","fixText":"Open the Exchange Management Shell and enter the following command:\n\nSet-ReceiveConnector -Identity <'IdentityName'> -AuthMechanism 'Tls'\n\nNote: The value must be in quotes.\n\nRepeat the process for each Receive connector.","ccis":["CCI-002418"]},{"vulnId":"V-259642","ruleId":"SV-259642r961632_rule","severity":"high","ruleTitle":"Exchange internal Send connectors must require encryption.","description":"The Simple Mail Transfer Protocol (SMTP) connector is used by Exchange to send and receive messages from server to server. Several controls work together to provide security between internal servers. This setting controls the encryption method used for communications between servers. With this feature enabled, only servers capable of supporting Transport Layer Security (TLS) will be able to send and receive mail within the domain.\n\nThe use of secure communication prevents eavesdroppers from reading or modifying communications between mail clients and servers. While sensitive message bodies should be encrypted by the sender at the client, requiring a secure connection from server to server adds protection by encrypting the sender and recipient information that cannot be encrypted by the sender.\n\nIndividually, channel security and encryption can be compromised by attackers. Used together, email becomes a more difficult target, and security is heightened. Failure to enable this feature gives eavesdroppers an opportunity to read or modify messages between servers.","checkContent":"Check the Email Domain Security Plan (EDSP) and determine which send connector is using which secure validation method. If no configuration setting is found, this is a finding.\n\nIf using \"DomainValidation\", open the Exchange Management Shell and enter the following command:\n\nGet-SendConnector | Select-Object -Property Name, Identity, TlsDomain\n \nIf the value of \"TlsDomain\" is not set to the value of the internal <'SMTP Domain'>, this is a finding.\n\nIf using \"DomainSecureEnabled\", open the Exchange Management Shell and enter the following command:\n\nGet-SendConnector | Select-Object -Property Name, Identity, DomainSecureEnabled\n\nIf the value of 'DomainSecureEnabled' is not set to 'True', this is a finding.\n\nNote: The wildcard character (*) is not supported in domains that are configured for mutual TLS authentication. The same domain must also be defined on the corresponding Receive connector and in the TLSReceiveDomainSecureList attribute of the transport configuration.","fixText":"If using \"DomainValidation\", open the Exchange Management Shell and enter the following command:\n\nSet-SendConnector -Identity <'Identity'> -TlsDomain -TlsAuthLevel DomainValidation -RequireTLS $true\n\nIf using \"DomainSecureEnabled\", open the Exchange Management Shell and enter the following command:\n\nSet-SendConnector -Identity <'ReceiveConnector'> -DomainSecureEnabled $true\n\nNote:\n- To use DomainSecureEnabled, DNSRouting must be set to $true.\n- The same domain must also be defined on the corresponding Receive connector and in the TLSReceiveDomainSecureList attribute of the transport configuration.","ccis":["CCI-002418"]},{"vulnId":"V-259643","ruleId":"SV-259643r961638_rule","severity":"medium","ruleTitle":"Exchange must render hyperlinks from email sources from non-.mil domains as unclickable.","description":"Active hyperlinks within an email are susceptible to attacks of malicious software or malware. The hyperlink could lead to a malware infection or redirect the website to another fraudulent website without the user's consent or knowledge. \n\nExchange does not have a built-in message filtering capability. DOD Enterprise Email (DEE) has created a custom resolution to filter messages from non-.mil users that have hyperlinks in the message body. The hyperlink within the messages will be modified, preventing end users from automatically clicking links.","checkContent":"Note: If using another DOD-approved anti-spam product for email or a DOD-approved Email Gateway spamming device, such as Enterprise Email Security Gateway (EEMSG), this is not applicable.\n\nNote: If system is on SIPRNet, this is not applicable.\n\nReview the Email Domain Security Plan (EDSP).\n\nDetermine the name of the Transport Agent.\n\nOpen the Windows PowerShell console and enter the following command:\n\nGet-TransportAgent -Name 'customAgent' | Format-List\n\nIf the value does not return \"customAgent\", this is a finding.\n\nNote: \"customAgent\" is the name of the custom agent developed to render hyperlink email sources from non .mil domains as unclickable.","fixText":"Update the EDSP to reflect the name of the Transport Agent.\n\nContact the DISA Enterprise Email Service Desk at disa.tinker.eis.mbx.dod-enterprise-services-service-desk@mail.mil and request the Agent and installation procedures.\n\nor\n\nContact DEE Engineering PMO and request the Agent and installation procedures.","ccis":["CCI-002420"]},{"vulnId":"V-259644","ruleId":"SV-259644r961683_rule","severity":"medium","ruleTitle":"Exchange must have the most current, approved Cumulative Update (CU) installed.","description":"The organization (including any contractor to the organization) must promptly install security-relevant software updates (e.g., patches, service packs, CUs, hot fixes). Flaws discovered during security assessments, continuous monitoring, incident response activities, or information system error handling must also be addressed.","checkContent":"Open the Exchange Management Shell and enter the following command:\n\nGet-ExchangeServer | Format-List Name, AdminDisplayVersion\n\nIf the value of \"AdminDisplayVersion\" does not return the most current, approved CU, this is a finding.","fixText":"Install the most current, approved CU.","ccis":["CCI-002605"]}]}