huntrule

Windows Defender antimalware grace period expired (Event ID 5101)

Alerts when Windows Defender signals its antimalware grace period expired via windefend Event ID 5101.

FreeReviewedSigma · High · v2
Product
windows
Service
windefend
Author
Ján Trenčanský, frack113 (SigmaHQ), DRL 1.1
Published
2020-07-28
Updated
2026-07-31
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 flags Windows Defender events where the antimalware platform grace period has expired (Event ID 5101). An attacker may attempt to reduce defensive coverage so malware, spyware, or potentially unwanted software can run with protection disabled. Telemetry required is Windows Defender windefend event logs containing EventID 5101.

Reporting behind it

Related detections9 linkedT1685 — drag to rearrange
Suspicious Windows Defender Exclusion of User Profile via PowerShell (via process_creation)
Malicious Vulnerable Driver Service Creation for BYOVD (via process_creation)
Malicious Microsoft Defender Disabled via Registry DisableAntiSpyware (via process_creation)
Suspicious Termination of Defender Tray Process via Taskkill
Malicious Windows Defender Disablement via MpCmdRun RemoveDefinitions
Malicious Unsigned VIB Installation on ESXi Host via esxcli (via process_creation)
Suspicious In-Memory PowerShell Execution from Web Server via Automation Assembly (via image_load)
Malicious EDR Evasion Driver Load from AnyDesk Directory via k.sys (via image_load)
Malicious Zemana Vulnerable Driver Load for EDR Termination (via image_load)
Windows Defender antimalware grace period expired (Event ID 5101)
Pivot detection · T1685 · 9 related

Changelog

v2
  1. v2
    Candidate ingested via manual entry.2026-07-31
  2. v1
    No changelog recorded for this version.2026-07-30

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