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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 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.
STIG Date
Microsoft Excel 2013 STIG 2016-12-20

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.
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".