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

ATT&CK techniques

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
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
Candidate ingested via manual entry.2026-07-31
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.

windows-defender-antimalware-grace-period-expired-event-id-5101-windefend-360a1340

title: Windows Defender antimalware grace period expired (Event ID 5101)
id: b9d951a9-cdec-48a9-a08f-654f68c75030
related:
  - id: fe34868f-6e0e-4882-81f6-c43aa8f15b62
    type: obsolete
  - id: 360a1340-398a-46b6-8d06-99b905dc69d2
    type: derived
status: stable
description: 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.
references:
  - https://learn.microsoft.com/en-us/defender-endpoint/troubleshoot-microsoft-defender-antivirus?view=o365-worldwide#event-id-5101
  - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.001/T1562.001.md
  - https://craigclouditpro.wordpress.com/2020/03/04/hunting-malicious-windows-defender-activity/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/builtin/windefend/win_defender_antimalware_platform_expired.yml
author: Ján Trenčanský, frack113, Huntrule Team
date: 2020-07-28
modified: 2023-11-22
tags:
  - attack.defense-impairment
  - attack.t1685
logsource:
  product: windows
  service: windefend
detection:
  selection:
    EventID: 5101
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1

Convert

This rule as a query you can run. Uses no unlock credit.

SplunkSPL