Title

Trust Bar Notifications for unsigned application add-ins must be blocked. (Cat II impact)

Discussion

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.

Check Content

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Publisher 2013 -> Security -> Trust Center "Disable Trust Bar Notification for unsigned application add-ins" must be "Enabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\15.0\publisher\security Criteria: If the value NoTBPromptUnsignedAddin is REG_DWORD = 1, this is not a finding.

Fix Text

Set the policy value for User Configuration -> Administrative Templates -> Microsoft Publisher 2013 -> Security -> Trust Center "Disable Trust Bar Notification for unsigned application add-ins" to "Enabled".

Additional Identifiers

Rule ID: SV-53243r1_rule

Vulnerability ID: V-17187

Group Title: DTOO131 - Trust Bar Notifications

Expert Comments

CCIs tied to check.

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