Detectionhightest

Suspicious PowerShell Encoded Command Patterns

Detects PowerShell command line patterns in combincation with encoded commands that often appear in malware infection chains

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Launch

Florian Roth (Nextron Systems)Created Tue May 24Updated Thu Jan 05b9d9cc83-380b-4ba3-8d8f-60c0e7e2930cwindows

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_flags:
        CommandLine|contains:
            - ' -e '
            - ' -en '
            - ' -enc '
            - ' -enco'
    selection_encoded:
        CommandLine|contains:
            - ' JAB'
            - ' SUVYI'
            - ' SQBFAFgA'
            - ' aWV4I'
            - ' IAB'
            - ' PAA'
            - ' aQBlAHgA'
    filter_gcworker:
        ParentImage|contains:
            - 'C:\Packages\Plugins\Microsoft.GuestConfiguration.ConfigurationforWindows\'
            - '\gc_worker.exe'
    condition: all of selection_* and not 1 of filter_*