The Active Directory (AD) implementation used with Windows Server 2003 has a feature called, autoenrollment that you can configure to automatically revoke and delete user certificates on the Certificate Authority (CA).
To set up the autoenrollment feature, follow these steps:
- Go to the Group Policy Objects (GPO) settings, and select Properties for the object, then click Edit and drill down until you get to "Object Type."
- Right click on "Autoenrollment Settings" and go to "Properties."
- Check "Enroll Certificates Automatically" and once the box appears, select the two checkboxes underneath it.
- Click OK and you're done.
Visit the Microsoft Web site for a more in depth explanation (http://microsoft.com).
The autoenrollment feature should add a little bit of extra system access security. If you choose not to use it, you have to delete all user accounts from the system manually. Also, remember that loose certificates sitting on compromised machines, stolen laptops or other errant equipment, can be exploited by users whose accounts may be gone, but whose ghosts aren't.