Detectionhightest

PowerShell Base64 Encoded Invoke Keyword

Detects UTF-8 and UTF-16 Base64 encoded powershell 'Invoke-' calls

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Martin Mueller, Harjot SinghCreated Fri May 20Updated Thu Apr 066385697e-9f1b-40bd-8817-f4a91f40508ewindows

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_enc:
        CommandLine|contains: ' -e'
    selection_cli_invoke:
        CommandLine|contains:
            # Invoke-
            # UTF-16LE
            - 'SQBuAHYAbwBrAGUALQ'
            - 'kAbgB2AG8AawBlAC0A'
            - 'JAG4AdgBvAGsAZQAtA'
            # UTF-8
            - 'SW52b2tlL'
            - 'ludm9rZS'
            - 'JbnZva2Ut'
    condition: all of selection_*