huntrule

Windows Process Creation: MpCmdRun.exe Removing All Windows Defender Definitions

Flags MpCmdRun.exe launched to remove all Windows Defender definition files.

FreeUnreviewedSigmahighv1
title: "Windows Process Creation: MpCmdRun.exe Removing All Windows Defender Definitions"
id: ba192ea6-4088-4854-93c4-fb747554ff5c
status: test
description: This rule identifies process creation events where MpCmdRun.exe is launched with arguments that remove all Windows Defender definition files. Attackers may impair defenses by deleting security definition data to reduce detection coverage before or during malicious activity. The detection relies on process creation telemetry, matching MpCmdRun.exe execution via both image attributes and command-line parameters for -RemoveDefinitions and -All.
references:
  - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.001/T1562.001.md
  - https://unit42.paloaltonetworks.com/unit42-gorgon-group-slithering-nation-state-cybercrime/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_mpcmdrun_remove_windows_defender_definition.yml
author: frack113, Huntrule Team
date: 2021-07-07
modified: 2023-07-18
tags:
  - attack.defense-impairment
  - attack.t1685
logsource:
  category: process_creation
  product: windows
detection:
  selection_img:
    - Image|endswith: \MpCmdRun.exe
    - OriginalFileName: MpCmdRun.exe
  selection_cli:
    CommandLine|contains|all:
      - " -RemoveDefinitions"
      - " -All"
  condition: all of selection_*
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 9719a8aa-401c-41af-8108-ced7ec9cd75c
    type: derived

What it detects

This rule identifies process creation events where MpCmdRun.exe is launched with arguments that remove all Windows Defender definition files. Attackers may impair defenses by deleting security definition data to reduce detection coverage before or during malicious activity. The detection relies on process creation telemetry, matching MpCmdRun.exe execution via both image attributes and command-line parameters for -RemoveDefinitions and -All.

Known false positives

  • Unknown

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.