Trust Bar Notifications for unsigned application add-ins must be blocked.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-17187	DTOO131	SV-53711r1_rule	ECSC-1	Medium

Description
If an application is configured to require all add-ins to be signed by a trusted publisher, any unsigned add-ins the application loads will be disabled and the application will display the Trust Bar at the top of the active window. The Trust Bar contains a message informing users about the unsigned add-in. If a user is allowed to make the determination to allow an unsigned add-in, it increases the risk of malicious code being introduced onto the user's computer or the network.

Description

If an application is configured to require all add-ins to be signed by a trusted publisher, any unsigned add-ins the application loads will be disabled and the application will display the Trust Bar at the top of the active window. The Trust Bar contains a message informing users about the unsigned add-in. If a user is allowed to make the determination to allow an unsigned add-in, it increases the risk of malicious code being introduced onto the user's computer or the network.

STIG	Date
Microsoft Excel 2013 STIG	2015-06-18

Details

Check Text ( C-47807r1_chk )
Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Excel 2013 -> Excel Options -> Security -> Trust Center "Disable Trust Bar Notification for unsigned application add-ins and block them" is set to "Enabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\15.0\excel\security Criteria: If the value NoTBPromptUnsignedAddin is REG_DWORD = 1, this is not a finding.

Check Text ( C-47807r1_chk )

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Excel 2013 -> Excel Options -> Security -> Trust Center "Disable Trust Bar Notification for unsigned application add-ins and block them" is set to "Enabled".

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

HKCU\Software\Policies\Microsoft\Office\15.0\excel\security

Criteria: If the value NoTBPromptUnsignedAddin is REG_DWORD = 1, this is not a finding.

Fix Text (F-46627r1_fix)
Set the policy value for User Configuration -> Administrative Templates -> Microsoft Excel 2013 -> Excel Options -> Security -> Trust Center "Disable Trust Bar Notification for unsigned application add-ins and block them" to "Enabled".