huntrule

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

Detects DLL loads with a specific IMPHASH consistent with EvtMuteHook.dll used for event log tampering.

FreeReviewedSigma · High · v2
Product
windows
Category
image_load
Author
Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2022-09-07
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 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

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Malicious Audit Policy Disabled by Command Line (via security)
Malicious Event Log Tampering via wevtutil Channel Disable by FunkSec Ransomware (via process_creation)
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
  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.