Exchange must have auto-forwarding of email to remote domains disabled or restricted.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-221205	EX16-ED-000040	SV-221205r612603_rule		Medium

Description
Attackers can use automated messages to determine whether a user account is active, in the office, traveling, and so on. An attacker might use this information to conduct future attacks. Ensure Automatic Forwards to remote domains are disabled, except for enterprise email that must be restricted to forward-only to .mil and .gov. domains. Before enabling this setting, first configure a remote domain.

Description

Attackers can use automated messages to determine whether a user account is active, in the office, traveling, and so on. An attacker might use this information to conduct future attacks. Ensure Automatic Forwards to remote domains are disabled, except for enterprise email that must be restricted to forward-only to .mil and .gov. domains. Before enabling this setting, first configure a remote domain.

STIG	Date
Microsoft Exchange 2016 Edge Transport Server Security Technical Implementation Guide	2020-12-10

Details

Check Text ( C-22920r411741_chk )
Non-Enterprise Mail Check Content: Open the Exchange Management Shell and enter the following command: Get-RemoteDomain \| Select Name, DomainName, Identity, AutoForwardEnabled If the value of "AutoForwardEnabled" is not set to "False", this is a finding. Enterprise Mail Check Content: Open the Exchange Management Shell and enter the following command: Get-RemoteDomain \| Select Name, DomainName, Identity, AutoForwardEnabled If the value of “AutoForwardEnabled” is “True” and “DomainName” is not set to a “.mil” and/or “.gov” domain(s), this is a finding.

Check Text ( C-22920r411741_chk )

Non-Enterprise Mail Check Content:

Open the Exchange Management Shell and enter the following command:

Get-RemoteDomain | Select Name, DomainName, Identity, AutoForwardEnabled

If the value of "AutoForwardEnabled" is not set to "False", this is a finding.

Enterprise Mail Check Content:

Open the Exchange Management Shell and enter the following command:

Get-RemoteDomain | Select Name, DomainName, Identity, AutoForwardEnabled

If the value of “AutoForwardEnabled” is “True” and “DomainName” is not set to a “.mil” and/or “.gov” domain(s), this is a finding.

Fix Text (F-22909r411742_fix)
For Non-Enterprise Mail Fix Text: Open the Exchange Management Shell and enter the following command: Set-RemoteDomain -Identity <'IdentityName'> -AutoForwardEnabled $false Note: The value must be in single quotes. For Enterprise Mail Fix Text, enter the following commands: New-RemoteDomain -Name -DomainName Note: NewDomainName must be either a ".mil" or ".gov" domain. Set-RemoteDomain -Identity <'IdentityName'> -AutoForwardEnabled $true

Fix Text (F-22909r411742_fix)

For Non-Enterprise Mail Fix Text:

Open the Exchange Management Shell and enter the following command:

Set-RemoteDomain -Identity <'IdentityName'> -AutoForwardEnabled $false

Note: The value must be in single quotes.

For Enterprise Mail Fix Text, enter the following commands:

New-RemoteDomain -Name -DomainName

Note: NewDomainName must be either a ".mil" or ".gov" domain.

Set-RemoteDomain -Identity <'IdentityName'> -AutoForwardEnabled $true