Detectionhightest

Potential Rundll32 Execution With DLL Stored In ADS

Detects execution of rundll32 where the DLL being called is stored in an Alternate Data Stream (ADS).

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Harjot SinghCreated Sat Jan 21Updated Wed Feb 089248c7e1-2bf3-4661-a22c-600a8040b446windows

Log Source

WindowsProcess Creation

ProductWindows← raw: windows

CategoryProcess Creation← raw: process_creation

Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.

Detection Logic

detection:
    selection_img:
        - Image|endswith: '\rundll32.exe'
        - OriginalFileName: 'RUNDLL32.EXE'
    selection_cli:
        # Example:
        #   rundll32 "C:\ads\file.txt:ADSDLL.dll",DllMain
        # Note: This doesn't cover the use case where a full path for the DLL isn't used. As it requires a more expensive regex
        CommandLine|re: '[Rr][Uu][Nn][Dd][Ll][Ll]32(\.[Ee][Xx][Ee])? \S+?\w:\S+?:'
    condition: all of selection_*