Security News > 2022 > July > Microsoft quietly fixes ShadowCoerce Windows NTLM Relay bug

Microsoft has confirmed it fixed a previously disclosed 'ShadowCoerce' vulnerability as part of the June 2022 updates that enabled attackers to target Windows servers in NTLM relay attacks.

This NTLM relay attack method can be used by threat actors to force unpatched servers to authenticate against servers under the attacker's control, leading to a takeover of the Windows domain.

As Gilles demonstrated, this protocol is also vulnerable to NTLM relay attacks that enable threat actors to force a domain controller to authenticate against a malicious NTLM relay under their control.

Microsoft still has to address the DFSCoerce Windows NTLM relay attack, which uses MS-DFSNM, a protocol that allows management of the Windows Distributed File System over an RPC interface.

Last month, security researcher Filip Dragovic released a DFSCoerce proof-of-concept script that can be used to relay authentication against arbitrary servers allowing users with limited access to a Windows domain to become a domain admin.

Security researchers and experts also told BleepingComputer that the best way to prevent such attacks is to follow Microsoft's advisory on mitigating the PetitPotam NTLM relay attack.

News URL

https://www.bleepingcomputer.com/news/microsoft/microsoft-quietly-fixes-shadowcoerce-windows-ntlm-relay-bug/