File Download Via Windows Defender MpCmpRun.EXE

detection:
  selection_cli:
    CommandLine|contains|all:
      - 'DownloadFile'
      - 'url'
  selection_img:
    - OriginalFileName: 'MpCmdRun.exe'
    - Image|endswith: '\MpCmdRun.exe'
    - CommandLine|contains: 'MpCmdRun.exe'
    - Description: 'Microsoft Malware Protection Command Line Utility'
  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 Matthew Matchen, 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 LOLBAS or GTFOBins documents for mpcmdrun.exe trip it: each is on its program’s page, read by CmdID.