Windows: Detect EvtMuteHook.dll Load by IMPHASH Match (SharpEvtMute)

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What it detects

This rule identifies a Windows process loading EvtMuteHook.dll by matching a specific IMPHASH value. Loading this DLL matters because it can be used by an event-log tampering tool to impair Windows event logging. The detection relies on DLL image-load telemetry that includes the file’s IMPHASH and correlates the presence of the image to the known hash.

Reporting behind it

Related detections9 linkedT1685.001 — drag to rearrange

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OCSP Responder Auditing Settings Changed or Disabled (via security)

Windows: Detect EvtMuteHook.dll Load by IMPHASH Match (SharpEvtMute)

Pivot detection · T1685.001 · 9 related

Changelog

v2

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-dll-load-sharpevtmute-evtmutehook-dll-imphash-49329257

title: "Windows: Detect EvtMuteHook.dll Load by IMPHASH Match (SharpEvtMute)"
id: 458bcafa-58f5-4d94-9bfe-330769f5e9b5
related:
  - id: bedfc8ad-d1c7-4e37-a20e-e2b0dbee759c
    type: similar
  - id: 49329257-089d-46e6-af37-4afce4290685
    type: derived
status: test
description: This rule identifies a Windows process loading EvtMuteHook.dll by matching a specific IMPHASH value. Loading this DLL matters because it can be used by an event-log tampering tool to impair Windows event logging. The detection relies on DLL image-load telemetry that includes the file’s IMPHASH and correlates the presence of the image to the known hash.
references:
  - https://github.com/bats3c/EvtMute
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/image_load/image_load_hktl_sharpevtmute.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2022-09-07
modified: 2024-11-23
tags:
  - attack.defense-impairment
  - attack.t1685.001
logsource:
  category: image_load
  product: windows
detection:
  selection:
    Hashes|contains: IMPHASH=330768A4F172E10ACB6287B87289D83B
  condition: selection
falsepositives:
  - Other DLLs with the same Imphash
level: high
license: DRL-1.1

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