Restricting Enrollment Agents
Once someone has an Enrollment Agent certificate, that person can enroll for a certificate and generate a smart card on behalf of anyone in the organization, including all domain admins. The resulting smart card could then be used to log on to the network and impersonate the real user. Because of the powerful capability of the Enrollment Agent certificate, it is strongly recommended that your organization maintain very strong security policies for these certificates.
Permitting an enrollment agent to enroll only a certain type of certificate to a certain group of users was not possible before Windows 2008. In Windows Server 2003 Enterprise Edition the enterprise CA does not provide any configurable means to control enrollment agents except by enforcing the application policy extension of the enrollment agent certificate, which verifies that the credentials grant the ability to enroll on behalf of other users, including the domain admins.
In Windows Server 2008 the PKI architecture of an enterprise has the possibility to restrict enrollment agents so that enrollment is only possible for a certain certificate template and a certain group of users. By providing a technical possibility to limit the scope of enrollment agents, an enterprise can is given a better tool to control the delegation of trust and the risk associated with granting that trust.
On a Windows Server 2008 Enterprise-based certification authority (CA), the restricted enrollment agent features allow an enrollment agent to be used for one or many certificate templates. For each certificate template, you can choose which users or security groups the enrollment agent can enroll on behalf of.
Note: The feature cannot constrain an enrollment agent based on a certain Active Directory organizational unit (OU) or container; you must use security groups instead. The restricted enrollment agent is not available on a Windows Server® 2008 Standard-based CA.
By using the Certificate Services snap-in, you can create a permissions list for each enrollment agent to configure which users or security groups an enrollment agent can enroll on behalf of for each certificate template.