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 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
Suspicious ThrottleStop Driver Abuse for Defense Evasion in Ransomware Attacks
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.