Detectionmediumtest

Elevated System Shell Spawned From Uncommon Parent Location

Detects when a shell program such as the Windows command prompt or PowerShell is launched with system privileges from a uncommon parent location.

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Launch
François Hubaut, Tim Shelton (update fp)Created Mon Dec 05Updated Thu Mar 06178e615d-e666-498b-9630-9ed363038101windows
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 Logic8 selectors
detection:
    selection_shell:
        - Image|endswith:
              - '\powershell.exe'
              - '\powershell_ise.exe'
              - '\pwsh.exe'
              - '\cmd.exe'
        - OriginalFileName:
              - 'PowerShell.EXE'
              - 'powershell_ise.EXE'
              - 'pwsh.dll'
              - 'Cmd.Exe'
    selection_user:
        User|contains: # covers many language settings
            - 'AUTHORI'
            - 'AUTORI'
        LogonId: '0x3e7'
    filter_main_generic:
        # Example 1:
        #   C:\Program Files\erl-23.2\erts-11.1.4\bin\erl.exe" -service_event ErlSrv_RabbitMQ -nohup -sname rabbit@localhost -s rabbit boot -boot start_sasl +W w +MBas ageffcbf +MHas ageffcbf +MBlmbcs 512 +MHlmbcs 512 +MMmcs 30 +P 1048576 +t 5000000 +stbt db +zdbbl 128000 +sbwt none +sbwtdcpu none +sbwtdio none -kernel inet_dist_listen_min 25672 -kernel inet_dist_listen_max 25672 -lager crash_log false -lager handlers []
        # Example 2:
        #   ParentImage: C:\Program Files (x86)\Varonis\DatAdvantage\GridCollector\VrnsRealTimeAlertsSvc.exe" /appid 000000ad-cb03-500b-9459-c46d000000ad
        #   CommandLine: C:\Windows\system32\cmd.exe /c C:\Program Files "(x86)\Varonis\DatAdvantage\GridCollector\handle_scopes.cmd C:\Collector" Working Share\VaronisWorkDirectoryCollector
        ParentImage|contains:
            - ':\Program Files (x86)\'
            - ':\Program Files\'
            - ':\ProgramData\'
            - ':\Windows\System32\'
            - ':\Windows\SysWOW64\'
            - ':\Windows\Temp\' # Installers
            - ':\Windows\WinSxS\'
    filter_optional_manageengine:
        # Example:
        #   ParentImage: C:/ManageEngine/ADManager Plus/pgsql/bin/postgres.exe" --forkarch 5380
        #   CommandLine: C:\Windows\system32\cmd.exe /c "IF EXIST archive.bat (archive.bat pg_wal\000000010000008E000000EA 000000010000008E000000EA)
        ParentImage|endswith: ':\ManageEngine\ADManager Plus\pgsql\bin\postgres.exe'
        Image|endswith: '\cmd.exe'
    filter_optional_asgard:
        CommandLine|contains: ':\WINDOWS\system32\cmd.exe /c "'
        CurrentDirectory|contains: ':\WINDOWS\Temp\asgard2-agent\'
    filter_optional_ibm_spectrumprotect:
        ParentImage|contains: ':\IBM\SpectrumProtect\webserver\scripts\'
        CommandLine|contains: ':\IBM\SpectrumProtect\webserver\scripts\'
    filter_main_parent_null:
        ParentImage: null
    filter_main_parent_empty:
        ParentImage:
            - ''
            - '-'
    condition: all of selection_* and not 1 of filter_main_* and not 1 of filter_optional_*
False Positives

Some legitimate applications may spawn shells from uncommon parent locations. Apply additional filters and perform an initial baseline before deploying.

Rule Metadata
Rule ID
178e615d-e666-498b-9630-9ed363038101
Status
test
Level
medium
Type
Detection
Created
Mon Dec 05
Modified
Thu Mar 06
Path
rules/windows/process_creation/proc_creation_win_susp_elevated_system_shell_uncommon_parent.yml
Raw Tags
attack.privilege-escalationattack.defense-evasionattack.executionattack.t1059
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