CmdID / Rules / Windows

Suspicious PowerShell Parameter Substring

A Sigma rule for process creation on Windows, by Florian Roth (Nextron Systems), Daniel Bohannon (idea), Roberto Rodriguez (Fix).

high 1 ATT&CK technique 2 programs it names

What it looks for

its detection, as SigmaHQ writes it

detection:
  selection:
    CommandLine|contains:
      - ' -windowstyle h '
      - ' -windowstyl h'
      - ' -windowsty h'
      - ' -windowst h'
      - ' -windows h'
      - ' -windo h'
      - ' -wind h'
      - ' -win h'
      - ' -wi h'
      - ' -win h '
      - ' -win hi '
      - ' -win hid '
      - ' -win hidd '
      - ' -win hidde '
      - ' -NoPr '
      - ' -NoPro '
      - ' -NoProf '
      - ' -NoProfi '
      - ' -NoProfil '
      - ' -nonin '
      - ' -nonint '
      - ' -noninte '
      - ' -noninter '
      - ' -nonintera '
      - ' -noninterac '
      - ' -noninteract '
      - ' -noninteracti '
      - ' -noninteractiv '
      - ' -ec '
      - ' -encodedComman '
      - ' -encodedComma '
      - ' -encodedComm '
      - ' -encodedCom '
      - ' -encodedCo '
      - ' -encodedC '
      - ' -encoded '
      - ' -encode '
      - ' -encod '
      - ' -enco '
      - ' -en '
      - ' -executionpolic '
      - ' -executionpoli '
      - ' -executionpol '
      - ' -executionpo '
      - ' -executionp '
      - ' -execution bypass'
      - ' -executio bypass'
      - ' -executi bypass'
      - ' -execut bypass'
      - ' -execu bypass'
      - ' -exec bypass'
      - ' -exe bypass'
      - ' -ex bypass'
      - ' -ep bypass'
      - ' /windowstyle h '
      - ' /windowstyl h'
      - ' /windowsty h'
      - ' /windowst h'
      - ' /windows h'
      - ' /windo h'
      - ' /wind h'
      - ' /win h'
      - ' /wi h'
      - ' /win h '
      - ' /win hi '
      - ' /win hid '
      - ' /win hidd '
      - ' /win hidde '
      - ' /NoPr '
      - ' /NoPro '
      - ' /NoProf '
      - ' /NoProfi '
      - ' /NoProfil '
      - ' /nonin '
      - ' /nonint '
      - ' /noninte '
      - ' /noninter '
      - ' /nonintera '
      - ' /noninterac '
      - ' /noninteract '
      - ' /noninteracti '
      - ' /noninteractiv '
      - ' /ec '
      - ' /encodedComman '
      - ' /encodedComma '
      - ' /encodedComm '
      - ' /encodedCom '
      - ' /encodedCo '
      - ' /encodedC '
      - ' /encoded '
      - ' /encode '
      - ' /encod '
      - ' /enco '
      - ' /en '
      - ' /executionpolic '
      - ' /executionpoli '
      - ' /executionpol '
      - ' /executionpo '
      - ' /executionp '
      - ' /execution bypass'
      - ' /executio bypass'
      - ' /executi bypass'
      - ' /execut bypass'
      - ' /execu bypass'
      - ' /exec bypass'
      - ' /exe bypass'
      - ' /ex bypass'
      - ' /ep bypass'
    Image|endswith:
      - '\powershell.exe'
      - '\pwsh.exe'
  condition: selection

The rule’s detection, its selections and fields in order of name. The whole rule, with its references and false positives, is on SigmaHQ, by Florian Roth (Nextron Systems), Daniel Bohannon (idea), Roberto Rodriguez (Fix), under the Detection Rule License 1.1. CmdID evaluates it on a command line alone: a test on what a command line cannot show, such as the parent process or the user, is not met.

Command lines that trip it

documented abuse, read by CmdID

The commands documented for cl_loadassembly.ps1, utilityfunctions.ps1 trip it: each is on its program’s page, read by CmdID.

Programs and files it names

their pages here

powershellpowershell.exe

ATT&CK

the techniques it is tagged with

T1059.001Command and Scripting Interpreter: PowerShell

Suspicious PowerShell Parameter Substring

What it looks for

Command lines that trip it

Programs and files it names

ATT&CK

Other rules for T1059.001 Command and Scripting Interpreter: PowerShell