Overview
When you uninstall a certification authority (CA), the certificates that were issued by the CA are typically still outstanding. If the outstanding certificates are processed by the various Public Key Infrastructure client computers, validation will fail, and those certificates will not be used.
This article describes how to revoke outstanding certificates and how to complete various other tasks that are required to successfully uninstall a CA. Additionally, this article describes several utilities that you can use to help you remove CA objects from your domain.
Step-by-Step
This step-by-step article describes how to decommission a Microsoft Windows enterprise CA, and how to remove all related objects from the Active Directory directory service.
Step 1: Revoke all active certificates that are issued by the enterprise CA
Depending from CA level in CA hierarchy different steps can be used to revoke all issued certificates. The following procedure should be used if your CA is root CA (with self-signed certificate):
- Click Start, point to Administrative Tools, and then click Certification Authority.
- Expand your CA, and then click the Issued Certificates folder.
- In the right pane, click one of the issued certificates, and then press CTRL+A to select all issued certificates.
- Right-click the selected certificates, click All Tasks, and then click Revoke Certificate.
- In the Certificate Revocation dialog box, click to select Cease of Operation as the reason for revocation, and then click OK.
If your CA is intermediate (or subordinate) CA you can revoke CA certificate at issuer:
- Logon to issuer CA with CA Manager or CA Administrator permissions.
- Click Start, point to Administrative Tools, and then click Certification Authority.
- Expand your CA, and then click the Issued Certificates folder.
- In the right pane find CA certificate to be decommissioned.
- Right-click the selected certificate, click All Tasks, and then click Revoke Certificate.
- In the Certificate Revocation dialog box, click to select Cease of Operation as the reason for revocation, and then click Ok.
Step 2: Increase the CRL publication interval
- In the Certification Authority Microsoft Management Console (MMC) snap-in, right-click the Revoked Certificates folder, and then click Properties.
- In the CRL Publication Interval box, type a suitably long value, and then click OK.
- Note The lifetime of the Certificate Revocation List (CRL) should be longer than the lifetime that remains for certificates that have been revoked.
- In the Certification Authority MMC snap-in, right-click the Revoked Certificates folder.
- Click All Tasks, and then click Publish.
- In the Publish CRL dialog box, click New CRL, and then click OK.
Step 4: Deny any pending requests
By default, an enterprise CA does not store certificate requests. However, an administrator can change this default behavior. To deny any pending certificate requests, follow these steps:
- In the Certification Authority MMC snap-in, click the Pending Requests folder.
- In the right pane, click one of the pending requests, and then press CTRL+A to select all pending certificates.
- Right-click the selected requests, click All Tasks, and then click Deny Request.
- To stop Certificate Services, click Start, click Run, type cmd, and the click OK.
- At the command prompt, type certutil -shutdown, and then press ENTER.
- To list all key stores for the local computer, type certutil -key at the command prompt. This command will display the names of all the installed cryptographic service providers (CSP) and the key stores that are associated with each provider. Among the listed key stores, you will see the name of your CA listed several times, as shown in the following example.
(1)Microsoft Base Cryptographic Provider v1.0:
1a3b2f44-2540-408b-8867-51bd6b6ed413
MS IIS DCOM ClientSYSTEMS-1-5-18
MS IIS DCOM Server
Windows2000 Enterprise Root CA
MS IIS DCOM ClientAdministratorS-1-5-21-436374069-839522115-1060284298-500
afd1bc0a-a93c-4a31-8056-c0b9ca632896
Microsoft Internet Information Server
NetMon
MS IIS DCOM ClientAdministratorS-1-5-21-842925246-1715567821-839522115-500
(5)Microsoft Enhanced Cryptographic Provider v1.0:
1a3b2f44-2540-408b-8867-51bd6b6ed413
MS IIS DCOM ClientSYSTEMS-1-5-18
MS IIS DCOM Server
Windows2000 Enterprise Root CA
MS IIS DCOM ClientAdministratorS-1-5-21-436374069-839522115-1060284298-500
afd1bc0a-a93c-4a31-8056-c0b9ca632896
Microsoft Internet Information Server
NetMon
MS IIS DCOM ClientAdministratorS-1-5-21-842925246-1715567821-839522115-500
- Delete the private key that is associated with the CA. To do this, type the following at a command prompt: certutil -delkey CertificateAuthorityName
- Note: If your CA name contains spaces, enclose the name in quotation marks. In this example, the CertificateAuthorityName is Windows2000 Enterprise Root CA. Therefore, the command line in this example is the following: certutil -delkey "Windows2000 Enterprise Root CA"
- List the key stores again to verify that the private key for your CA has been deleted.
After you delete the private key for your CA, uninstall Certificate Services. To do this, follow these steps:
- Close the Certification Authority MMC snap-in if it is still open.
- Click Start, point to Control Panel, and then click Add or Remove Programs.
- Click Add/Remove Windows Components.
- In the Components box, click to clear the Certificate Services check box, click Next, and then follow the instructions in the Windows Components Wizard to complete the removal of Certificate Services.
When Microsoft Certificate Services is installed on a server that is a member of a domain, several objects are created in the configuration container in Active Directory. These objects are the following:
- certificateAuthority object
- Located in CN=AIA,CN=Public Key Services,CN=Services,CN=Configuration,DC=ForestRootDomain.
- Contains the CA certificate for the CA.
- Published Authority Information Access (AIA) location.
- crlDistributionPoint object
- Located in CN=ServerName,CN=CDP,CN=Public Key Service,CN=Services,CN=Configuration,DC=ForestRoot,DC=com.
- Contains the CRL periodically published by the CA.
- Published CRL Distribution Point (CDP) location.
- certificationAuthority object
- Located in CN=Certification Authorities,CN=Public Key Services,CN=Services,CN=Configuration,DC=ForestRoot,DC=com.
- Contains the CA certificate for the CA.
- pKIEnrollmentService object
- Located in CN=Enrollment Services,CN=Public Key Services,CN=Services,CN=Configuration,DC=ForestRoot,DC=com.
- Created by the enterprise CA.
- Contains information about the types of certificates the CA has been configured to issue. Permissions on this object can control which security principals can enroll against this CA.
For Public Key Infrastructure (PKI) client computers to successfully process these outstanding certificates, the computers must locate the Authority Information Access (AIA) and CRL distribution point paths in Active Directory. It is a good idea to revoke all outstanding certificates, extend the lifetime of the CRL, and publish the CRL in Active Directory. If the outstanding certificates are processed by the various PKI clients, validation will fail, and those certificates will not be used.
If it is not a priority to maintain the CRL distribution point and AIA in Active Directory, you can remove these objects. Do not remove these objects if you expect to process one or more of the formerly active digital certificates.
Remove all Certification Services objects from Active Directory
Note You should not remove certificate templates from Active Directory until after you remove all CA objects in the Active Directory forest.
To remove all Certification Services objects from Active Directory, follow these steps:
- Determine the CACommonName of the CA. To do this, follow these steps:
- Click Start, click Run, type cmd in the Open box, and then click OK.
- Type certutil, and then press ENTER.
Make a note of the Name value that belongs to your CA. You will need the CACommonName for later steps in this procedure.
- Click Start, point to Administrative Tools, and then click Active Directory Sites and Services.
- On the View menu, click Show Services Node.
- Expand Services, expand Public Key Services, and then click the AIA folder.
- In the right pane, right-click the CertificationAuthority object for your CA, click Delete, and then click Yes.
- In the left pane of the Active Directory Sites and Services MMC snap-in, click the CDP folder.
- In the right pane, locate the container object for the server where Certificate Services is installed. Right-click the container, click Delete, and then click Yes two times.
- In the left pane of the Active Directory Sites and Services MMC snap-in, click the Certification Authorities node.
- In the right pane, right-click the CertificationAuthority object for your CA, click Delete, and then click Yes.
- In the left pane of the Active Directory Sites and Services MMC snap-in, click the Enrollment Services node.
- In the right pane, verify that the pKIEnrollmentService object for your CA was removed when Certificate Services was uninstalled. If the object is not deleted, right-click the object, click Delete, and then click Yes.
If you did not locate all the objects, some objects may be left in the Active Directory after you perform these steps. To clean up after a CA that may have left objects in Active Directory, follow these steps to determine whether any AD objects remain:
- Type the following command at a command line, and then press ENTER: ldifde -r "cn=CACommonName" -d "CN=Public Key Services,CN=Services,CN=Configuration,DC=ForestRoot,DC=com" -f output.ldf
- In this command, CACommonName represents the Name value that you determined in step 1. For example, if the Name value is "CA1 Contoso," type the following:
- ldifde -r "cn=CA1 Contoso" -d "cn=public key services,cn=services,cn=configuration,dc=contoso,dc=com” -f remainingCAobjects.ldf
- Open the remainingCAobjects.ldf file in Notepad. Replace the term "changetype: add" with "changetype: delete." Then, verify whether the Active Directory objects that you will delete are legitimate.
- At a command prompt, type the following command, and then press ENTER to delete the remaining CA objects from Active Directory: ldifde -i -f remainingCAobjects.ldf
- Delete the certificate templates if you are sure that all of the certificate authorities have been deleted. Repeat step 12 to determine whether any AD objects remain.
- Important You must not delete the certificate templates unless all the certificate authorities have been deleted. If the templates are accidentally deleted, follow these steps:
- Make sure that you are logged on to a server that is running Certificate Services as Enterprise administrator.
- At a command prompt, type the following command, and then press ENTER: cd %windir%\system32
- Type the following command, and then press ENTER: regsvr32 /i:i /n /s certcli.dll
- This action re-creates the certificate templates in Active Directory.
- To delete the certificate templates, follow these steps.
- In the left pane of the "Active Directory Sites and Services" MMC snap-in, click the Certificate Templates folder.
- In the right pane, click a certificate template, and then press CTRL+A to select all templates. Right-click the selected templates, click Delete, and then click Yes.
Step 7: Delete certificates published to the NtAuthCertificates object
Using CERTUTIL.EXE
After you delete the CA objects, you have to delete the CA certificates that are published to the NtAuthCertificates object. Use either of the following commands to delete certificates from within the NTAuthCertificates store:
Services,CN=Services,CN=Configuration,DC=ForestRoot,DC=com?cACertificate?base?objectclass=certificationAuthority"
certutil -viewdelstore "ldap:///CN=NtAuthCertificates,CN=Public Key
Services,CN=Services,CN=Configuration,DC=ForestRoot,DC=com?cACertificate?base?objectclass=pKIEnrollmentService
Note You must have Enterprise Administrator permissions to perform this task.
The -viewdelstore action invokes the certificate selection UI on the set of certificates in the specified attibute. You can view the certificate details. You can cancel out of the selection dialog to make no changes. If you select a certificate, that certificate is deleted when the UI closes and the command is fully executed.
Use the following command to see the full LDAP path to the NtAuthCertificates object in your Active Directory:
certutil -store -? | findstr "CN=NTAuth"
Using PKIView.msc
For a GUI method of removing certificates from the NTAuthCertificates store, use PKIView.msc. You may need to install the appropriate RSAT tools for Certificate Services if Certificate Services was removed in a previous step:
- Click Start and Run or, in the Search programs and files box, type in PKIView.msc then press Enter.
- Click OK to acknowledge any errors relating to enumerating CAs in the PKI.
- In the tree-pane of the pkiview console, right-click Enterprise PKI then click Manage AD Containers.
- The NtAuthCertificates tab is the default tab and lists certificates in the container.
- On the NtAuthCertificates tab, select the certificate to be deleted and then click Remove.
Step 8: Delete the CA database
When Certification Services is uninstalled, the CA database is left intact so that the CA can be re-created on another server.
To remove the CA database, delete the %systemroot%\System32\Certlog folder.
Step 9: Clean up domain controllers
After the CA is uninstalled, the certificates that were issued to domain controllers must be removed.
To remove certificates that were issued to the Windows Server 2000 domain controllers, use the Dsstore.exe utility from the Microsoft Windows 2000 Resource Kit.
To remove certificates that have been issued to the Windows Server 2000 domain controllers, follow these steps:
- Click Start, click Run, type cmd, and then press ENTER.
- On a domain controller, type dsstore -dcmon at the command prompt, and then press ENTER
- Type 3, and then press ENTER. This action deletes all certificates on all domain controllers.
Note The Dsstore.exe utility will try to validate domain controller certificates that are issued to each domain controller. Certificates that do not validate are removed from their respective domain controller.
To remove certificates that were issued to the Windows Server 2003 domain controllers, follow these steps.Important Do not use this procedure if you are using certificates that are based on version 1 domain controller templates.
- Click Start, click Run, type cmd, and then press ENTER.
- At the command prompt on a domain controller, type certutil -dcinfo deleteBad.
To force application of the security policy, follow these steps:
- Click Start, click Run, type cmd in the Open box, and then press ENTER.
- At a command prompt, type the appropriate command for the corresponding version of the operating system, and then press ENTER:
For Windows Server 2000: secedit /refreshpolicy machine_policy /enforce
For Windows Server 2003 and higher: gpupdate /force
Cheers!
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