NTLMv1 vs NTLMv2: Digging into an NTLM Downgrade Attack

Overview During the summer, my colleague Derya Yavuz and I published an article on some of the different methods we’ve leveraged to elevate privileges within Active Directory environments. We discussed authentication coercion techniques such as PrinterBug, PetitPotam, and DFSCoerce. One of the techniques we mentioned in that article was performing an NTLM downgrade attack to […]

Elevating Privileges with Authentication Coercion Using DFSCoerce

Background In our previous blog post, we talked about the recently-published DFSCoerce utility which is useful for forcing NTLM or Kerberos authentication by interacting with the Distributed File Service (DFS) over Remote Procedure Calls (RPC) on Windows. This forces the victim to authenticate into the attacker’s machine, very much like authentication coercion tools like PetitPotam […]

How to Detect DFSCoerce

Background On 18 June 2022, security researcher Filip Dragovic published proof-of-concept code for a new forced authentication technique named DFSCoerce. This technique, inspired by other forced authentication techniques like PetitPotam and SpoolSample, often is used to force a victim Windows host to authenticate to an attacker’s machine. The attacker can then relay the credentials to […]