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Building a Certificate Authority in Windows Server 2019 Part 4 – Certificate Revocation Policies

4.1 Enable the Online Responder Role

The OCSP Responder role is a component of Active Directory Certificate Services that is used to reduce overhead with CRLs on your Network. It can check for revoked Certificates much faster than with regular CRLs and can update clients of their status.

  1. On the TFS-CA01 Server, open the Server Manager Console (servermanager.exe), click on the Manage menu, and click on Add Roles and Features to start the installation wizard.
  2. On the Before You Begin screen, click the Next button to continue.
  3. On the Installation Type screen, select the option for Role-based or feature-based installation and click the Next button to continue.
  4. On the Server Selection screen, verify that the TFS-CA01.corp.tfslabs.com Server is selected and click Next to continue.
  5. On the Server Roles screen, expand the Active Directory Certificate Services option and select the Online Responder role.
  6. The installation wizard will ask to install the necessary management tools for the role. Click the Add Features button to continue.
  7. On the Server Roles screen, click the Next button to continue.
  8. On the Features screen, click the Next button to continue.
  9. On the Confirmation screen, select the option to Restart the destination server automatically if required. When prompted with a warning about restarting the Server, click the Yes button (the Server must restart in order to continue). Click the Install button to continue.
  10. Once the installation is completed, click the Close button.
  11. Restart the TFS-CA01 Server if it did not restart automatically as part of the installation.

4.2 Configure the Online Responder Role

Once the OCSP Responder role has been added to the TFS-CA01 Server, it can be configured.

  1. To begin the configuration of the Online Responder Service, open the Server Manager Console (servermanager.exe). Click the Notifications icon in the upper-right hand corner and click the Configure Active Directory Certificate Services on the destination server link in the Post-deployment Configuration box.
  2. On the Credentials screen, verify that the Administrator Credentials is set to a Domain Administrator Account and click Next to continue.
  3. On the Role Services screen, select the option for Online Responder and click Next to continue.
  4. On the Confirmation screen, click on the Configure button to continue.
  5. Once the installation is completed, click the Close button.

Once the Role has been installed, verify that the OCSP folder is present in the IIS Manager Console. To do this, open the Internet Information Services (IIS) Manager Console and expand the TFS-CA01 > Sites > Default Web Site folder. The ocsp folder should be listed.

If the ocsp folder is not present, run the following command in an Administrative Command Prompt:

Certutil -vocsproot

The IIS Service will need to be restarted afterwards if this command is run.

4.3 Add the OCSP URL to the Enterprise CA

Once the OCSP Role has been installed, the URL can now be added to the Subordinate CA Certificate.

  1. In the Certification Authority Console (certsrv.msc) on the TFS-CA01 Server, in the Console tree right-click on TFS Labs Enterprise CA, and then select Properties.
  2. On the Extensions tab, under Select extension, select Authority Information Access (AIA), and then click Add.
  3. In the Location field, enter in http://ocsp.corp.tfslabs.com/ocsp and then click OK.
  4. Select Include in the online certificate status protocol (OCSP) extension and click the OK button (ensure that the Include in the AIA extension of issued certificates is not selected).
  1. When prompted by the Certification Authority dialog box to restart Active Directory Certificate Services, click Yes.

4.4 Configure and Publish the OCSP Response Signing Certificate

The OCSP Response Signing Certificate will be used by the OCSP Responder Service in order to manage the OCSP Services for the organization.

  1. Open the Certification Authority Console (certsrv.msc) on the TFS-CA01 Server, ensure that the TFS Labs Enterprise CA Server is expanded in the Console tree.
  2. Right-click on Certificate Templates and then click Manage. The Certificate Templates Console window will open and displays the certificate templates stored in Active Directory.
  3. In the details pane, right-click on the OCSP Response Signing template and then click Duplicate Template.
  4. On the Properties of New Template window, click on the General tab. Change the name of the template from Copy of OCSP Response Signing to TFS Labs OCSP Response Signing.
  5. On the Security tab select Authenticated Users and enable the Enroll permission. Click OK.
  6. On the Security tab add the TFS-CA01 Server and enable the Read and Enroll permission. Click OK.
  7. Close the Certificate Templates Console.
  8. In the Certification Authority Console, right-click Certificate Templates, then select New > Certificate Template to Issue.
  9. In the Enable Certificate Templates dialog box, click TFS Labs OCSP Response Signing and then click OK.

4.5 Configure Revocation Configuration on the Online Responder

Once the OCSP Certificates have been configured, the OCSP Responder Role can now be configured.

  1. Open the Online Responder Management Console (ocsp.msc) on the TFS-CA01 Server.
  2. Right-click on Revocation Configuration and then click Add Revocation Configuration.
  3. On the Getting started with adding a revocation configuration screen, click Next to continue.
  4. On the Name the Revocation Configuration screen, enter TFS Labs Enterprise CA in the Name field, and then click Next to continue.
  5. On the Select CA Certificate Location screen, ensure that Select a certificate for an Existing enterprise CA is selected, then click Next to continue.
  6. On the Choose CA Certificates screen, ensure that Browse CA certificates published in Active Directory is selected, and then click Browse.
  7. On the Select Certification Authority dialog box, ensure that TFS Labs Enterprise CA is selected, and then click OK. Click the Next button to continue.
  8. On the Select Signing Certificate screen, use the default options and then click Next to continue.
  9. On the Revocation Provider screen, click the Provider button.
  10. For the LDAP and HTTP locations in the Base CRLs window, clear the Refresh CRLs based on their validity periods. In the Update CRLs at this refresh interval (min) field, enter 15, and then click OK.
  11. Click Finish to close the window.
  12. In the Online Responder Management Console, expand Array Configuration and then click TFS-CA01.corp.tfslabs.com.
  13. Review the Revocation Configuration Status in the middle pane to ensure there is a signing certificate present and the status reports as OK. If so, the provider is successfully using the current configuration.

4.6 Add the OCSP URL to Group Policy

Once the OCSP Role has been installed, the URL can now be added to the Subordinate CA Certificate in Group Policy to ensure that it is being deployed to the organization.

  1. Open the Group Policy Management Console (gpmc.msc) on the TFS-DC01 Server.
  2. In the root of the corp.tfslabs.com Domain, right-click on the TFS Labs Certificates GPO and select the Edit option.
  3. In the Group Policy Management Editor window, open the Computer Configuration > Policies > Windows Settings > Security Settings > Public Key Policies node.
  4. Open the Intermediate Certification Authorities folder, right-click on the TFS Labs Enterprise CA Certificate and select Properties.
  5. In the TFS Labs Enterprise CA Properties window, click on the OCSP tab and in the text field to the left of the Add URL button, enter http://ocsp.corp.tfslabs.com/ocsp and click the Add URL button. Click the OK button to close the window.
  6. Close the Group Policy Management Console.
  7. Once the Certificates have been added to Group Policy, allow up to 1 hour for the Certificates to be deployed to the entire Active Directory Forest.

4.7 Verify OCSP Status

Once the OCSP Role has been configured, you can now verify if it is working correctly within the PKI Infrastructure.

  1. On the TFS-CA01 Server, open the Enterprise PKI Console (PKIView.msc).
  2. Under the Enterprise PKI node, click on the TFS Labs Certificate Authority Server and check that the status of OCSP is OK.

If there are no issues being reported with OCSP then you can proceed to the next step. If there is an issue with OCSP, then the most likely issue is with the CA Exchange Certificate. It most likely does not know about OCSP since it was generated before the OCSP Role was configured, so it will need to be recreated.

  1. Open the Certification Authority Console (certsrv.msc) on the TFS-CA01 Server, ensure that the TFS Labs Enterprise CA Server is expanded in the Console tree.
  2. Under the Issued Certificates folder, look for a Certificate using the CA Exchange (CAExchange) Template.
  3. Right-click on the Certificate and select the All Tasks > Revoke Certificate option.
  4. On the Certificate Revocation window, click the Yes button to revoke the Certificate.
  5. Open an Administrative Command Prompt and run the following command request a new certificate:
certutil -cainfo xchg
  1. On the TFS-CA01 Server, open the Enterprise PKI Console (PKIView.msc).
  2. Under the Enterprise PKI node, click on the TFS Labs Certificate Authority Server and check that the status of OCSP is OK.

4.8 Verify OCSP Connectivity

To verify that the OCSP Responder Server can communicate with devices on the TFS Labs Domain a certificate will need to be exported and run through the URL Retrieval Tool. This can be easily accomplished on the TFS-CA01 Server.

  1. On the TFS-CA01 Server, export the TFS Labs Enterprise CA Certificate as a DER Encoded Binary the root of the C:\ Drive (C:\TFS Labs Enterprise CA.cer).
  2. Run the following command in an Administrative Command Prompt to launch the URL Retrieval Tool:
Certutil -URL “C:\TFS Labs Enterprise CA.cer”
  1. In the Retrieve box, select the option for OCSP (from AIA) and then click the Retrieve button.
  2. If there is no issue with the OCSP Service, the result returned should be: Verified OCSP (0.0) http://ocsp.corp.tfslabs.com/ocsp.

OCSP Status Results

Note: This step may not return a result immediately and that is nothing to be concerned about. If you run this test and nothing is returned in the results, you may want to run this test later using the TFS-WIN10 Workstation once Certificate Deployments is completed.

Certificate Authority in Windows Server 2019

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