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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-228356	EX16-MB-000030	SV-228356r508018_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. Verify Automatic Forwards to remote domains are disabled, except for enterprise mail that must be restricted to forward only to .mil and .gov. domains. Before enabling this setting, configure a remote domain.

STIG	Date
Microsoft Exchange 2016 Mailbox Server Security Technical Implementation Guide	2020-10-01

Details

Check Text ( C-30589r496864_chk )
Non-Enterprise Mail Check Content: Open the Exchange Management Shell and enter the following command: Get-RemoteDomain \| Select Identity, AutoForwardEnabled If the value of AutoForwardEnabled is not set to "False", this is a finding. Enterprise Mail Check Content: If the value of "AutoForwardEnabled" is set to "True", this is not a finding. and In the Exchange Management Shell, enter the following command: Get-RemoteDomain If the value of "RemoteDomain" is not set to ".mil" and/or ".gov" domain(s), this is a finding.

Check Text ( C-30589r496864_chk )

Non-Enterprise Mail Check Content:

Open the Exchange Management Shell and enter the following command:

Get-RemoteDomain | Select Identity, AutoForwardEnabled

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

Enterprise Mail Check Content:

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

and

In the Exchange Management Shell, enter the following command:

Get-RemoteDomain

If the value of "RemoteDomain" is not set to ".mil" and/or ".gov" domain(s), this is a finding.

Fix Text (F-30574r496865_fix)
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. Enterprise Mail Fix Text: New-RemoteDomain -Name -DomainName Note: must either be a .mil or .gov domain. Set-RemoteDomain -Identity <'RemoteDomainIdentity'> -AutoForwardEnabled $true Note: The value must be in single quotes.

Fix Text (F-30574r496865_fix)

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.

Enterprise Mail Fix Text:

New-RemoteDomain -Name -DomainName

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

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

Note: The value must be in single quotes.