A vulnerability has been identified in SIMATIC BATCH V9.1 (All versions), SIMATIC Information Server 2020 (All versions), SIMATIC Information Server 2022 (All versions), SIMATIC PCS 7 V9.1 (All versions), SIMATIC Process Historian 2020 (All versions), SIMATIC Process Historian 2022 (All versions), SIMATIC WinCC Runtime Professional V17 (All versions), SIMATIC WinCC Runtime Professional V18 (All versions), SIMATIC WinCC Runtime Professional V19 (All versions), SIMATIC WinCC Runtime Professional V20 (All versions), SIMATIC WinCC Runtime Professional V21 (All versions), SIMATIC WinCC V7.5 (All versions), SIMATIC WinCC V8.0 (All versions), SIMATIC WinCC V8.1 (All versions). Affected systems do not properly secure their remote user authentication with the deprecated NTLM protocol. This could allow unauthenticated remote attackers, who have achieved a machine in the middle position, to relay NTLM authentication and impersonate a legitimate user. The potential impact depends on the services that are accessible, e.g. a SQL server used by WinCC.