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Applies to BloodHound Enterprise and CE They also have permission to enroll for a certificate template that permits enrollment by enrollment agents and can be used for authentication. Additionally, they also have enrollment permissions for an enterprise CA with the necessary templates published. This enterprise CA is trusted for NT authentication in the forest, along with the CA certificate chain up to the root CA certificate. This setup lets the principal enroll certificates for any AD forest user or computer, enabling authentication and impersonation of any AD forest user or computer without their credentials, unless the target user or computer is protected by enrollment agent restrictions on the enterprise CA.

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Abuse Info

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Windows

Step 1: Use Certify (2.0) to request an enrollment agent certificate. 
Certify.exe request --ca CORPDC01.CORP.LOCAL\CORP-CORPDC01-CA --template Vuln-EnrollmentAgent
If the enrollment fails with an error message stating that the Email or DNS name is unavailable and cannot be added to the Subject or Subject Alternate name, then it is because the enrollee principal does not have their ‘mail’ or ‘dNSHostName’ attribute set, which is required by the certificate template. The ‘mail’ attribute can be set on both user and computer objects but the ‘dNSHostName’ attribute can only be set on computer objects. Computers have validated write permission to their own ‘dNSHostName’ attribute by default, but neither users nor computers can write to their own ‘mail’ attribute by default. Step 2: Use the enrollment agent certificate to issue a certificate request on behalf of another user to a certificate template that allows for authentication and permits enrollment agent enrollment. 
Certify.exe request-agent --ca ca01.corp.local\CORP-CA01-CA --template User --target itadmin --agent-pfx <agent cert base64>
If the enrollment fails with an error message stating that the Email or DNS name is unavailable and cannot be added to the Subject or Subject Alternate name, then it is because the target principal does not have their ‘mail’ or ‘dNSHostName’ attribute set, which is required by the certificate template. Choose another target with the given attribute set. The certificate PFX is printed to the console in a base64-encoded format. Step 3: With Rubeus, use the issued certificate to authenticate to the domain and request a TGT, specifying the identity you intend to impersonate: 
Rubeus.exe asktgt /user:itadmin /domain:corp.local /certificate:<cert base64> /ptt

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Linux

Step 1: Use Certify to request an enrollment agent certificate. 
certipy req -u 'user@corp.local' -p 'password' -dc-ip 'DC_IP' -target 'ca_host' -ca 'ca_name
If the enrollment fails with an error message stating that the Email or DNS name is unavailable and cannot be added to the Subject or Subject Alternate name, then it is because the enrollee principal does not have their ‘mail’ or ‘dNSHostName’ attribute set, which is required by the certificate template. The ‘mail’ attribute can be set on both user and computer objects but the ‘dNSHostName’ attribute can only be set on computer objects. Computers have validated write permission to their own ‘dNSHostName’ attribute by default, but neither users nor computers can write to their own ‘mail’ attribute by default. Step 2: Use the enrollment agent certificate to issue a certificate request on behalf of another user to a certificate template that allow for authentication and permit enrollment agent enrollment. 
certipy req -u 'user@corp.local' -p 'password' -dc-ip 'DC_IP' -target 'ca_host' -ca 'ca_name
Save the certificate as itadminenrollment.pem and the private key as itadminenrollment.key. If the enrollment fails with an error message stating that the Email or DNS name is unavailable and cannot be added to the Subject or Subject Alternate name, then it is because the target principal does not have their ‘mail’ or ‘dNSHostName’ attribute set, which is required by the certificate template. Choose another target with the given attribute set. Step 3: Request a ticket granting ticket (TGT) from the domain, specifying the target identity to impersonate and the PFX-formatted certificate created in Step 2. 
certipy auth -pfx administrator.pfx -dc-ip 172.16.126.128

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Opsec Considerations

When the affected certificate authority issues the certificate to the attacker, it will retain a local copy of that certificate in its issued certificates store. Defenders may analyze those issued certificates to identify illegitimately issued certificates and identify the principal that requested the certificate, as well as the target identity the attacker is attempting to impersonate.

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Edge Schema

Source: User, Group, Computer
Destination: Domain
Traversable: Yes

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References

This edge is related to the following MITRE ATT&CK tactic and techniques:

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Abuse and Opsec references