EX16-ED-000170 - Exchange internal Send connectors must use domain security (mutual authentication Transport Layer Security). - TlsAuthLevel

Information

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.

The 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.

Individually, 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.

Solution

Open the Exchange Management Shell and enter the following command:

Set-SendConnector <'IdentityName'> -DomainSecureEnabled $true

Note: The <IdentityName> value must be in single quotes.

Repeat the procedures for each send connector.

The following commands can be executed if smarthosts are used:

Set-SendConnector <'IdentityName'> -RequireTLS $true -DNSRoutingEnabled $False -TlsAuthLevel $DomainValidation

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_MS_Exchange_2016_Y21M12_STIG.zip

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-23, CAT|II, CCI|CCI-001184, Rule-ID|SV-221218r811174_rule, STIG-ID|EX16-ED-000170, STIG-Legacy|SV-95227, STIG-Legacy|V-80517, Vuln-ID|V-221218

Plugin: Windows

Control ID: 69ee641d071bbaaf7c8b06697201917fc3aa5517c675939db591d12a14e36eec