Microsoft has released security updates that block the PetitPotam NTLM relay attack that allows a threat actor to take over a Windows domain. The attack forces a domain controller to authenticate against another server using the MS-EFSRPC API functions without authentication. Microsoft blocks the attack as part of the August 2021 Patch Tuesday updates. Microsoft warns that installing this update may affect backup software that utilizes the EFS API OpenEncryptedFileRaw(A/W) function. Backup software that uses the API continues to work in all versions of Windows (local and remote)
Source: https://www.bleepingcomputer.com/news/microsoft/windows-security-update-blocks-petitpotam-ntlm-relay-attacks/