Bad Opsec Defaults Sacrificial Processes With Improper Arguments

detection:
  filter_optional_chromium_installer:
    CommandLine|endswith: 'rundll32.exe'
    Image|endswith: '\rundll32.exe'
    ParentCommandLine|contains: '--uninstall '
    ParentImage|contains:
      - '\AppData\Local\BraveSoftware\Brave-Browser\Application\'
      - '\AppData\Local\Google\Chrome\Application\'
    ParentImage|endswith: '\Installer\setup.exe'
  filter_optional_edge_update:
    CommandLine|endswith: 'rundll32.exe'
    Image|endswith: '\rundll32.exe'
    ParentImage|contains: '\AppData\Local\Microsoft\EdgeUpdate\Install\{'
  selection_regasm:
    CommandLine|endswith: 'regasm.exe'
    Image|endswith: '\regasm.exe'
  selection_regsvcs:
    CommandLine|endswith: 'regsvcs.exe'
    Image|endswith: '\regsvcs.exe'
  selection_regsvr32:
    CommandLine|endswith: 'regsvr32.exe'
    Image|endswith: '\regsvr32.exe'
  selection_rundll32:
    CommandLine|endswith: 'rundll32.exe'
    Image|endswith: '\rundll32.exe'
  selection_werfault:
    CommandLine|endswith: 'WerFault.exe'
    Image|endswith: '\WerFault.exe'
  condition: 1 of selection_* 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 Oleg Kolesnikov @securonix invrep_de, oscd.community, Florian Roth (Nextron Systems), Christian Burkard (Nextron Systems), 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.

None of the everyday examples and documented commands on CmdID’s program pages trips it. To see whether a command line does, paste it into CmdID.