Microsoft Exchange 2016 Edge Transport Server STIG Version Comparison
Microsoft Exchange 2016 Edge Transport Server Security Technical Implementation Guide
There are 4 differences between versions v2 r2 (Jan. 22, 2021) (the "left" version) and v2 r4 (July 27, 2022) (the "right" version).
Check EX16-ED-000170 was changed between these two versions. Green, underlined text was added, red, struck-out text was removed.
Exchange internal Send connectors must use domain security (mutual authentication Transport Layer Security).
Open the Exchange Management Shell and enter the following command: Get-SendConnector | Select Name, Identity, DomainSecureEnabled For DomainSecureEnabled, DNSRoutingEnabled, RequireTLS, TlsAuthLevel For each send connector: If the send connector, connector if does not use a smarthost and the value of "DomainSecureEnabled" is not set to "True", this is a finding. If the "TlsAuthLevel" parameter is send connector does use a smarthost, "DomainSecureEnabled" will be set to "False". If "DomainValidation" then the "TlsDomain" parameter send connector does use a smarthost "DNSRoutingEnabled", "RequireTLS", and "TlsAuthLevel" must be set. If the send connector using a smart host has a value for “DNSRoutingEnabled” that is not required if "DNSRoutingEnabled" parameter is set to “False”, this is a finding. If "$false". The "DNSRoutingEnabled" parameter must be "$true" If the send connector using a smarthost has a value of "DomainSecureEnabled" for “RequireTLS” that is "$true". not set to “True”, this is a finding. If the send connector using a smarthost has a value for “TlsAuthLevel” that is not set to “DomainValidation”, this is a finding.
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.
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. connector. The following commands can be executed if smarthosts are used: Set-SendConnector <'IdentityName'> -RequireTLS $true -DNSRoutingEnabled $False -TlsAuthLevel $DomainValidation