Detectionhightest

Regsvr32 DLL Execution With Suspicious File Extension

Detects the execution of REGSVR32.exe with DLL files masquerading as other files

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Florian Roth (Nextron Systems), François HubautCreated Mon Nov 29Updated Wed Aug 27089fc3d2-71e8-4763-a8a5-c97fbb0a403ewindows

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: '\regsvr32.exe'
        - OriginalFileName: 'REGSVR32.EXE'
    selection_cli:
        CommandLine|endswith:
            # Add more image extensions
            # https://twitter.com/Max_Mal_/status/1542461200797163522/photo/3
            - '.bin'
            - '.bmp'
            - '.cr2'
            - '.dat'
            - '.eps'
            - '.gif'
            - '.ico'
            - '.jpeg'
            - '.jpg'
            - '.log'
            - '.nef'
            - '.orf'
            - '.png'
            - '.raw'
            - '.rtf'
            - '.sr2'
            - '.temp'
            - '.tif'
            - '.tiff'
            - '.tmp'
            - '.txt'
    condition: all of selection_*