Intranet with Safe Zones for automatic picture downloads must be configured.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-17634	DTOO275	SV-54049r1_rule		Medium

Description
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.

Description

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.

STIG	Date
Microsoft Outlook 2013 STIG	2018-09-05

Details

Check Text ( C-47988r1_chk )
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.

Check Text ( C-47988r1_chk )

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 (F-46928r1_fix)
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".