huntrule

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

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

FreeReviewedSigma · High · v1
Product
windows
Category
process_creation
Author
frack113 (SigmaHQ), DRL 1.1
Published
2021-07-07
Updated
2026-07-30
AnalysisDetection

ATT&CK techniques

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

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.

Reporting behind it

Related detections9 linkedT1685 — drag to rearrange
Malicious Microsoft Defender Tampering via PowerShell Preference Cmdlets
Suspicious Windows Defender Exclusion via Add-MpPreference (via process_creation)
Malicious Windows Defender Service Tampering via PowerShell (via process_creation)
Windows Defender Disabled via DisableAntiSpyware Registry Key
Suspicious Vulnerable Intel Ethernet Driver Load for BYOVD via SCATTERED SPIDER (via driver_load)
Malicious Defender Disable And Executable Exclusion Via Registry
Malicious UAC Disable via EnableLUA Registry Modification (via registry_set)
Malicious AMSI and ETW Patching via PowerShell Script
Malicious PowMix AMSI Bypass via amsiInitFailed
Windows Process Creation: MpCmdRun.exe Removing All Windows Defender Definitions
Pivot detection · T1685 · 9 related

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