New PetitPotam NTLM Relay Attack Lets Hackers Take Over Windows Domains
Jul 26, 2021
A newly uncovered security flaw in the Windows operating system can be exploited to coerce remote Windows servers, including Domain Controllers, to authenticate with a malicious destination, thereby allowing an adversary to stage an NTLM relay attack and completely take over a Windows domain. The issue, dubbed " PetitPotam ," was discovered by security researcher Gilles Lionel, who shared technical details and proof-of-concept (PoC) code last week, noting that the flaw works by forcing "Windows hosts to authenticate to other machines via MS-EFSRPC EfsRpcOpenFileRaw function." MS-EFSRPC is Microsoft's Encrypting File System Remote Protocol that's used to perform "maintenance and management operations on encrypted data that is stored remotely and accessed over a network." Specifically, the attack enables a domain controller to authenticate against a remote NTLM under a bad actor's control using the MS-EFSRPC interface and share its authen