Windows Hello ESS means Enhanced Sign-in Security, a Windows Hello mode that adds stronger isolation to biometric sign-in. It is designed to keep facial recognition or fingerprint matching away from the normal user session, using protected hardware and tighter security boundaries.
This matters because biometric logon is a high-trust path. If malware can inspect, replay, or interfere with the sign-in pipeline, it may weaken access control even when passwords are not exposed. ESS helps defenders reduce that risk by limiting what the operating system and applications can touch during authentication. In practice, organizations enable it on supported devices, then test camera or sensor compatibility, enrollment behavior, and policy enforcement before broad rollout. Attackers may try to target the sign-in flow, but ESS raises the bar by making biometric data and matching logic harder to reach from user-mode compromise.