External/Internet bound automated response messages must be disabled.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-33601	Exch-2-811	SV-44021r1_rule	ECSC-1	Medium

Description
SPAM originators, in an effort to refine mailing lists, sometimes use a technique where they monitor transmissions for automated bounce back messages, such as 'Out of Office' messages. Automated messages include such items as Out of Office responses, non-delivery messages, or automated message forwarding. Automated bounce back messages can be used by a third party to determine if users exist on the server. This can result in the disclosure of active user accounts to third parties, paving the way for possible future attacks.

Description

SPAM originators, in an effort to refine mailing lists, sometimes use a technique where they monitor transmissions for automated bounce back messages, such as 'Out of Office' messages. Automated messages include such items as Out of Office responses, non-delivery messages, or automated message forwarding. Automated bounce back messages can be used by a third party to determine if users exist on the server. This can result in the disclosure of active user accounts to third parties, paving the way for possible future attacks.

STIG	Date
MS Exchange 2010 Edge Transport Server STIG	2019-01-02

Details

Check Text ( C-41708r1_chk )
Open the Exchange Management Shell and enter the following command: Get-RemoteDomain -Identity 'default' \| Select Name, Identity, AllowedOOFType If the value of 'AllowedOOFType' is set to 'External' or 'ExternalLegacy', this is a finding.

Fix Text (F-37493r1_fix)
Open the Exchange Management Shell and enter the following command: Set-RemoteDomain -AllowedOOFType 'InternalLegacy' -Identity 'default'