Check: EX16-ED-000340
Microsoft Exchange 2016 Edge Transport Server STIG:
EX16-ED-000340
(in versions v2 r5 through v1 r1)
Title
Exchange messages with a blank sender field must be filtered. (Cat II impact)
Discussion
By performing filtering at the perimeter, up to 90 percent 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 resources and risk infection while evaluating them, it is recommended that these messages be filtered immediately upon receipt and not forwarded to end users.
Check Content
This requirement is N/A for SIPR enclaves. This requirement is N/A if the organization subscribes to EEMSG or other similar DoD enterprise protections for email services. Open the Exchange Management Shell and enter the following command: Get-SenderFilterConfig | Select Name, BlankSenderBlockingEnabled If the value of "BlankSenderBlockingEnabled" is not set to "True", this is a finding.
Fix Text
Open the Exchange Management Shell and enter the following command: Set-SenderFilterConfig -BlankSenderBlockingEnabled $true
Additional Identifiers
Rule ID: SV-221233r879653_rule
Vulnerability ID: V-221233
Group Title: SRG-APP-000261
Expert Comments
CCIs
Number | Definition |
---|---|
CCI-001308 |
The information system automatically updates spam protection mechanisms. |
Controls
Number | Title |
---|---|
SI-8 (2) |
Automatic Updates |