Title

Missing Root Certificates warning must be enforced. (Cat II impact)

Discussion

When Outlook accesses a certificate, it validates that it can trust the certificate by examining the root certificate of the issuing CA. If the root certificate can be trusted, then certificates issued by the CA can also be trusted. If Outlook cannot find the root certificate, it cannot validate that any certificates issued by that CA can be trusted. An attacker may compromise a root certificate and then remove the certificate in an attempt to conceal the attack. By default, Outlook displays a warning message when a CRL is not available.

Check Content

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Cryptography -> Signature Status dialog box "Missing root certificates" is set to "Enabled (Error)". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\15.0\outlook\security Criteria: If the value SigStatusNoTrustDecision is REG_DWORD = 2, this is not a finding.

Fix Text

Set the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Cryptography -> Signature Status dialog box "Missing root certificates" to "Enabled (Error)".

Additional Identifiers

Rule ID: SV-54033r1_rule

Vulnerability ID: V-17756

Group Title: DTOO268 - Missing Root Certificates

Expert Comments

CCIs tied to check.

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