Change PowerShell Policies to an Insecure Level

detection:
  filter_main_powershell_core:
    CommandLine|contains:
      - '-NoProfile -ExecutionPolicy Bypass -File "C:\Program Files\PowerShell\7\'
      - '-NoProfile -ExecutionPolicy Bypass -File "C:\Program Files (x86)\PowerShell\7\'
    ParentImage:
      - 'C:\Windows\SysWOW64\msiexec.exe'
      - 'C:\Windows\System32\msiexec.exe'
  filter_optional_avast:
    CommandLine|contains:
      - '-ExecutionPolicy ByPass -File "C:\Program Files\Avast Software\Avast'
      - '-ExecutionPolicy ByPass -File "C:\Program Files (x86)\Avast Software\Avast\'
    ParentImage|contains:
      - 'C:\Program Files\Avast Software\Avast\'
      - 'C:\Program Files (x86)\Avast Software\Avast\'
      - '\instup.exe'
  selection_img:
    - OriginalFileName:
        - 'powershell_ise.exe'
        - 'PowerShell.EXE'
        - 'pwsh.dll'
    - Image|endswith:
        - '\powershell_ise.exe'
        - '\powershell.exe'
        - '\pwsh.exe'
  selection_level:
    CommandLine|contains:
      - 'Bypass'
      - 'Unrestricted'
  selection_option:
    CommandLine|contains:
      - '-executionpolicy '
      - ' -ep '
      - ' -exec '
  condition: all of selection_* and not 1 of filter_main_* and not 1 of filter_optional_*

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 frack113, 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.

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