Create a user account (say, serviceca), on behalf of which the system shall request user certificates in the Certification Authority and set the rights to work with certification authority for this account:
1. Open the Certification Authority tool, select the certification authority and switch to its Properties.
2. Click Add... in the Security tab.
3. Specify the service account (serviceca) as the user.
4. Define the Issue and Manage Certificates and Request Certificates permissions for the account and save settings by clicking ОК.