IE Trusted Zones assumed 'trusted' must be blocked.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-17564	DTOO273 - Outlook	SV-33540r1_rule		Medium

Description
Malicious users can send HTML e-mail messages with embedded Web beacons, which are pictures and other content from external servers that can be used to track whether specific recipients open the message. Viewing an e-mail message that contains a Web beacon provides confirmation that the recipient's e-mail address is valid, which leaves the recipient vulnerable to additional spam and harmful e-mail. To reduce the risk from Web beacons, Outlook disables external content in e-mail messages by default, unless the content is considered "safe" as determined by the check boxes in the Automatic Download section of the Trust Center. Depending on how these options are configured, safe content can include content in messages from addresses defined in the Safe Senders and Safe Recipients Lists used by the Junk E-mail filter, content from SharePoint discussion boards, and content from Web sites in the Trusted sites zone in Internet Explorer. By default, Outlook considers trusted sites from Internet Explorer safe, and automatically downloads content from them, which could potentially include Web beacons.

Description

Malicious users can send HTML e-mail messages with embedded Web beacons, which are pictures and other content from external servers that can be used to track whether specific recipients open the message. Viewing an e-mail message that contains a Web beacon provides confirmation that the recipient's e-mail address is valid, which leaves the recipient vulnerable to additional spam and harmful e-mail. To reduce the risk from Web beacons, Outlook disables external content in e-mail messages by default, unless the content is considered "safe" as determined by the check boxes in the Automatic Download section of the Trust Center. Depending on how these options are configured, safe content can include content in messages from addresses defined in the Safe Senders and Safe Recipients Lists used by the Junk E-mail filter, content from SharePoint discussion boards, and content from Web sites in the Trusted sites zone in Internet Explorer. By default, Outlook considers trusted sites from Internet Explorer safe, and automatically downloads content from them, which could potentially include Web beacons.

STIG	Date
Microsoft Outlook 2010 STIG	2018-04-04

Details

Check Text ( C-34014r1_chk )
The policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2010 -> Security -> Automatic Picture Download Settings “Block Trusted Zones” must be set to “Enabled”. Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\14.0\outlook\options\mail Criteria: If the value TrustedZone is REG_DWORD = 0, this is not a finding.

Check Text ( C-34014r1_chk )

The policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2010 -> Security -> Automatic Picture Download Settings “Block Trusted Zones” must be set to “Enabled”.

Procedure: Use the Windows Registry Editor to navigate to the following key:

HKCU\Software\Policies\Microsoft\Office\14.0\outlook\options\mail

Criteria: If the value TrustedZone is REG_DWORD = 0, this is not a finding.

Fix Text (F-29702r1_fix)
Set the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2010 -> Security -> Automatic Picture Download Settings “Block Trusted Zones” to “Enabled”.