Detectionmediumtest

Suspicious Execution of Powershell with Base64

Commandline to launch powershell with a base64 payload

Convert In Phoenix Studio

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

Launch

François HubautCreated Sun Jan 02Updated Thu Jan 05fb843269-508c-4b76-8b8d-88679db22ce7windows

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:
        Image|endswith:
            - \powershell.exe
            - \pwsh.exe
        CommandLine|contains:
            - ' -e '
            - ' -en '
            - ' -enc '
            - ' -enco'
            - ' -ec '
    filter_encoding:
        CommandLine|contains: ' -Encoding '
    filter_azure:
        ParentImage|contains:
            - 'C:\Packages\Plugins\Microsoft.GuestConfiguration.ConfigurationforWindows\'
            - '\gc_worker.exe'
    condition: selection and not 1 of filter_*