PowerShell Download and Execution Cradles

detection:
  selection_download:
    CommandLine|contains:
      - '.DownloadString('
      - '.DownloadFile('
      - 'Invoke-WebRequest '
      - 'iwr '
      - 'Invoke-RestMethod '
      - 'irm '
  selection_iex:
    CommandLine|contains:
      - ';iex $'
      - '| IEX'
      - '|IEX '
      - 'I`E`X'
      - 'I`EX'
      - 'IE`X'
      - 'iex '
      - 'IEX ('
      - 'IEX('
      - 'Invoke-Expression'
  condition: all of 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), 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 syncappvpublishingserver.exe, syncappvpublishingserver.vbs trip it: each is on its program’s page, read by CmdID.