Title

The computer clock synchronization tolerance must be limited to 5 minutes or less. (Cat II impact)

Discussion

This setting determines the maximum time difference (in minutes) that Kerberos will tolerate between the time on a client's clock and the time on a server's clock while still considering the two clocks synchronous. In order to prevent replay attacks, Kerberos uses timestamps as part of its protocol definition. For timestamps to work properly, the clocks of the client and the server need to be in sync as much as possible. Satisfies: SRG-OS-000112-GPOS-00057, SRG-OS-000113-GPOS-00058

Check Content

This applies to domain controllers. It is NA for other systems. Verify the following is configured in the Default Domain Policy. Open "Group Policy Management". Navigate to "Group Policy Objects" in the Domain being reviewed (Forest >> Domains >> Domain). Right-click on the "Default Domain Policy". Select "Edit". Navigate to Computer Configuration >> Policies >> Windows Settings >> Security Settings >> Account Policies >> Kerberos Policy. If the "Maximum tolerance for computer clock synchronization" is greater than "5" minutes, this is a finding.

Fix Text

Configure the policy value in the Default Domain Policy for Computer Configuration >> Windows Settings >> Security Settings >> Account Policies >> Kerberos Policy >> "Maximum tolerance for computer clock synchronization" to a maximum of "5" minutes or less.

Additional Identifiers

Rule ID: SV-224969r852344_rule

Vulnerability ID: V-224969

Group Title: SRG-OS-000112-GPOS-00057

Expert Comments

CCIs tied to check.

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