Detectionmediumtest

Suspicious XOR Encoded PowerShell Command

Detects presence of a potentially xor encoded powershell command

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Open this Sigma rule in the converter with the YAML preloaded and ready for backend selection.

Sami Ruohonen, Harish Segar, Tim Shelton, Teymur Kheirkhabarov, Vasiliy Burov, oscd.community, Nasreddine Bencherchali (Nextron Systems)Created Wed Sep 05Updated Mon Jan 30bb780e0c-16cf-4383-8383-1e5471db6cf9windows

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'
        - Description: 'Windows PowerShell'
        - Product: 'PowerShell Core 6'
    selection_cli_xor:
        CommandLine|contains: 'bxor'
    selection_cli_other:
        CommandLine|contains:
            - 'ForEach'
            - 'for('
            - 'for '
            - '-join '
            - "-join'"
            - '-join"'
            - '-join`'
            - '::Join'
            - '[char]'
    condition: all of selection_*