You’ve created a new certificate for your Lync Server 2013 services and attempt to assign it to Server default and Web services internal:
However, the assignment fails and the following error message is displayed:
Command execution failed: The process does not possess the 'SeSecurityPrivilege' privilege which is required for this operation.
One of the reasons why the certificate assignment would fail with the error message above is if an administrator or group policy has removed the administrators group from the Lync Server’s Manage auditing and security log policy as shown in the following screenshot:
To correct the problem, simply grant the local administrators group the Manage auditing and security log policy permissions:
You should be able to assign certificates to Lync Server 2013 services once the above has been completed.