Adversaries may abuse features of Winlogon to execute DLLs and/or executables when a user logs in. Winlogon.exe is a Windows component responsible for actions at logon/logoff as well as the secure attention sequence (SAS) triggered by Ctrl-Alt-Delete. Registry entries in HKLM\Software[\\Wow6432Node\\]\Microsoft\Windows NT\CurrentVersion\Winlogon\ and HKCU\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\ are used to manage additional helper programs and functionalities that support Winlogon.(Citation: Cylance Reg Persistence Sept 2013) Malicious modifications to these Registry keys may cause Winlogon to load and execute malicious DLLs and/or executables. Specifically, the following subkeys have been known to be possibly vulnerable to abuse: (Citation: Cylance Reg Persistence Sept 2013) * Winlogon\Notify - points to notification package DLLs that handle Winlogon events * Winlogon\Userinit - points to userinit.exe, the user initialization program executed when a user logs on * Winlogon\Shell - points to explorer.exe, the system shell executed when a user logs on Adversaries may take advantage of these features to repeatedly execute malicious code and establish persistence.

Linked Issues

Issuelinks
Linktype Issue
is related to Techniques
is blocked by Detect Winlogon Helper DLL Abuse via Registry and Process Artifacts on Windows
is blocked by Execution Prevention
is blocked by User Account Management
is blocked by Access Restriction For Change
is blocked by Least Functionality
is blocked by Continuous Monitoring
is blocked by Endpoint File Integrity Monitoring (FIM)
is blocked by Separation of Duties (SoD)
is blocked by Identification & Authentication for Organizational Users
is blocked by Account Management
is blocked by Access Enforcement
is blocked by Least Privilege
is blocked by Remote Access
is blocked by Non-Persistence
is blocked by Memory Protection
is blocked by Input Data Validation
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