Skip to main content
Applies to BloodHound Enterprise and CE They also have enrollment permission for an enterprise CA with the necessary templates published. This enterprise CA is trusted for NT authentication in the forest, and chains up to a root CA for the forest. The enterprise CA is configured with the EDITF_ATTRIBUTESUBJECTALTNAME2 flag allowing enrollees to specify a Subject Alternate Name (SAN) identifying another principal during certificate enrollment of any published certificate template. This setup allow an attacker principal to obtain a malicious certificate as any AD forest user or computer and use it for authentication and impersonation without knowing their credentials.

​
Abuse Info

​
Windows

Step 1: Use Certify (2.0) to request enrollment in the affected template, specifying the affected enterprise CA and target principal to impersonate (include the SID URL if strong mapping is enforced): 
Certify.exe request --ca rootdomaindc.forestroot.com\forestroot-RootDomainDC-CA --template ESC6 --upn ForestRootDA --sid-url S-1-5-21-2697957641-2271029196-387917394-500
The certificate PFX is printed to the console in a base64-encoded format. 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: With Rubeus, use the certificate to authenticate to the domain and request a TGT, specifying the identity you intend to impersonate: 
Rubeus asktgt /user:ForestRootDA /domain:forestroot.com /certificate:<cert base64> /ptt
Step 3 (optional): Verify the TGT by listing it with klist: 
klist

​
Linux

Step 1: Use Certipy to request enrollment in the affected template, specifying the affected certification authority and target principal to impersonate: 
certipy req -u john@corp.local -p Passw0rd -ca corp-DC-CA -target ca.corp.local -template ESC6 -upn administrator@corp.local
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: Request a ticket granting ticket (TGT) from the domain, specifying the certificate created in Step 1 and the IP of a domain controller:: 
 certipy auth -pfx administrator.pfx -dc-ip 172.16.126.128
If the authentication fails then it may be because the DC enforces strong certificate mapping. This requirement can be met by including a URL parameter in the SAN with the target’s SID, however not supported by Certipy. See the Windows abuse section for example.

​
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.

​
Edge Schema

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

​
References

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

​
Abuse and Opsec references