Detectionhightest

Potential PowerShell Obfuscation Via Reversed Commands

Detects the presence of reversed PowerShell commands in the CommandLine. This is often used as a method of obfuscation by attackers

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Launch

Teymur Kheirkhabarov, Vasiliy Burov, oscd.community, Tim SheltonCreated Sun Oct 11Updated Wed May 31b6b49cd1-34d6-4ead-b1bf-176e9edba9a4windows

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:
              - '\powershell.exe'
              - '\pwsh.exe'
        - OriginalFileName:
              - 'PowerShell.EXE'
              - 'pwsh.dll'
    selection_cli:
        CommandLine|contains:
            - 'hctac'
            - 'kaerb'
            - 'dnammoc'
            - 'ekovn' # Also covers 'ekovni'
            - 'eliFd'
            - 'rahc'
            - 'etirw'
            - 'golon'
            - 'tninon'
            - 'eddih'
            - 'tpircS'
            - 'ssecorp'
            - 'llehsrewop'
            - 'esnopser'
            - 'daolnwod'
            - 'tneilCbeW'
            - 'tneilc'
            - 'ptth'
            - 'elifotevas'
            - '46esab'
            - 'htaPpmeTteG'
            - 'tcejbO'
            - 'maerts'
            - 'hcaerof'
            - 'retupmoc'
    filter_main_encoded_keyword:
        # We exclude usage of encoded commands as they might generate FPs as shown here:
        #   https://github.com/SigmaHQ/sigma/pull/2720
        #   https://github.com/SigmaHQ/sigma/issues/4270
        CommandLine|contains:
            - ' -EncodedCommand '
            - ' -enc '
    condition: all of selection_* and not 1 of filter_main_*