Wednesday, April 9, 2014

Breaking MSFT Kerberos With Responder

I've been working on a way to get MS Kerberos v5 hashes via the Browser protocol automatically with no user interaction on a given network.
(click on the pics if they don't display correctly).

Often you see these requests in wireshark on an internal penetration test:

So I came up with a tool that automates kerberos' connection for these:

Which shows up like this in Wireshark:

Here's how the attack works :
1) Poison a NBT-NS lookup on the domain controller service, wait for a SamLogonRequest, answer with a LogonSAMUserUnknownEX then wait for a LogonPrimaryQuery and answer with a LogonSAMUserUnknownEX.
2) Setup a smb server which responds to a NegotiateProtocolRequest with the supported mech list set as kerberos:
and wait for the Kerberos AS-REQ on UDP 88.

Responder will then take care of the hash parsing and formating:

 And will make it ready for hashcat (-m 7500):

This will be included in the next release of Responder (

Game over MSKerberosV5.