Title

Intranet with Safe Zones for automatic picture downloads must be configured. (Cat II impact)

Discussion

Malicious email senders can send HTML email messages with embedded Web beacons, which are pictures and other content from external servers that can be used to track whether recipients open the messages. Viewing email messages with Web beacons in them provides confirmation that the recipient's email address is valid, which leaves the recipient vulnerable to additional spam and harmful email. By default, Outlook does not download external content in HTML email messages from untrusted senders over the local intranet. If this configuration is changed, Outlook will display external content in all HTML email messages received via the local intranet, which could include Web beacons.

Check Content

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Automatic Picture Download Settings "Include Intranet in Safe Zones for Automatic Picture Download" is set to "Disabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\15.0\outlook\options\mail Criteria: If the value Intranet is REG_DWORD = 0, this is not a finding.

Fix Text

Set the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Automatic Picture Download Settings "Include Intranet in Safe Zones for Automatic Picture Download" to "Disabled".

Additional Identifiers

Rule ID: SV-54049r1_rule

Vulnerability ID: V-17634

Group Title: DTOO275 - Incl. Intranet with Safe Zone

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.