Messages with a blank sender field must be filtered.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
Exch-ED-230	Exch-ED-230	Exch-ED-230_rule		Medium

Description
By performing filtering at the perimeter, up to 90% of SPAM, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. Anonymous email (messages with blank sender fields) cannot be replied to. Messages formatted in this way may be attempting to hide their true origin to avoid responses, or to SPAM any receiver with impunity while hiding their source of origination. Rather than spend resource and risk infection while evaluating them, it is recommended that these messages be filtered immediately upon receipt and not forwarded to end users.

Description

By performing filtering at the perimeter, up to 90% of SPAM, malware, and other undesirable messages are eliminated from the message stream rather than admitting them into the mail server environment. Anonymous email (messages with blank sender fields) cannot be replied to. Messages formatted in this way may be attempting to hide their true origin to avoid responses, or to SPAM any receiver with impunity while hiding their source of origination. Rather than spend resource and risk infection while evaluating them, it is recommended that these messages be filtered immediately upon receipt and not forwarded to end users.

STIG	Date
Microsoft Exchange 2010 Edge Transport Server Role	2012-05-31

Details

Check Text ( C-_chk )
Open the Exchange Management Shell and enter the following command. Get-SenderFilterConfig \| Select BlankSenderBlockingEnabled If the value of "BlankSenderBlockingEnabled" is not set to "False", this is a finding.

Fix Text (F-_fix)
Open the Exchange Management Shell and enter the following command. Set-SenderFilterConfig -BlankSenderBlockingEnabled $false