Detect Malicious Password Filter DLL Registration

Technique Detected:  Password Filter DLL | T1556.002

ID: DET0472
Domains: Enterprise
Analytics: AN1303
Version: 1.0
Created: 21 October 2025
Last Modified: 21 October 2025

Analytics

AN1303

Detects suspicious registration of new password filter DLLs into the authentication process. Correlates registry modifications to LSASS Notification Packages with subsequent DLL creation and loading events. Observes anomalous file placement of DLLs in system directories followed by LSASS loading the new filter during logon/password change activity.

Log Sources
Data Component Name Channel
Windows Registry Key Modification (DC0063) WinEventLog:Security EventCode=4657
File Creation (DC0039) WinEventLog:Sysmon EventCode=11
Module Load (DC0016) WinEventLog:Sysmon EventCode=7
Mutable Elements
Field Description
RegistryPath Specific registry path monitored for modification (e.g., HKLM\SYSTEM\CurrentControlSet\Control\Lsa\Notification Packages).
AllowedDLLs Known and approved password filter DLLs; deviations from baseline may indicate malicious injection.
TimeWindow Time window for correlating registry modification, file creation, and module load events.
FilePathPatterns Expected directories for legitimate password filter DLLs; anomalous paths may signal compromise.