Windows Process Access: WerFaultSecure accessing MsMpEng with dbgcore.dll/dbghelp.dll call traces

Alerts on WerFaultSecure.exe accessing MsMpEng.exe with dbgcore/dbghelp DLLs in the call trace.

FreeReviewedSigma · High · v2

Product: windows
Category: process_access
Author: Swachchhanda Shrawan Poudel (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2025-11-27
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 identifies process access events on Windows where WerFaultSecure.exe accesses MsMpEng.exe, and the call trace includes dbgcore.dll and dbghelp.dll. Such debugger-related module traces alongside access to MsMpEng may indicate attempts to interfere with endpoint security operations. It relies on Sysmon ProcessAccess telemetry that includes call trace data for the accessing and target processes.

Reporting behind it

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Windows Process Access: WerFaultSecure accessing MsMpEng with dbgcore.dll/dbghelp.dll call traces

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-process-access-werfaultsecure-to-msmpeng-exe-with-dbgcore-dll-dbghelp-dl-387df17d

title: "Windows Process Access: WerFaultSecure accessing MsMpEng with dbgcore.dll/dbghelp.dll call traces"
id: ec16a6e9-5b3a-41e8-9f48-b593d58dbb08
related:
  - id: 8a2f4b1c-3d5e-4f7a-9b2c-1e4f6d8a9c2b
    type: similar
  - id: 1f0b4cac-9c81-41f4-95d0-8475ff46b3e2
    type: similar
  - id: 387df17d-3b04-448f-8669-9e7fd5e5fd8c
    type: derived
status: experimental
description: This rule identifies process access events on Windows where WerFaultSecure.exe accesses MsMpEng.exe, and the call trace includes dbgcore.dll and dbghelp.dll. Such debugger-related module traces alongside access to MsMpEng may indicate attempts to interfere with endpoint security operations. It relies on Sysmon ProcessAccess telemetry that includes call trace data for the accessing and target processes.
references:
  - https://blog.axelarator.net/hunting-for-edr-freeze/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_access/proc_access_win_werfaultsecure_msmpeng_access.yml
author: Swachchhanda Shrawan Poudel (Nextron Systems), Huntrule Team
date: 2025-11-27
tags:
  - attack.defense-impairment
  - attack.t1685
logsource:
  category: process_access
  product: windows
  definition: |
    Requires Sysmon Event ID 10 (ProcessAccess) with CallTrace enabled.
    Example sysmon config snippet with grouping, as logging individual ProcessAccess events can generate excessive logs:
    <ProcessAccess onmatch="include">
        <Rule groupRelation="and">
        <TargetImage condition="end with">\MsMpEng.exe</TargetImage>
        <SourceImage condition="end with">\WerFaultSecure.exe</SourceImage>
        </Rule>
    </ProcessAccess>
detection:
  selection:
    SourceImage|endswith: \WerFaultSecure.exe
    TargetImage|endswith: \MsMpEng.exe
    CallTrace|contains:
      - \dbgcore.dll
      - \dbghelp.dll
  condition: selection
falsepositives:
  - Legitimate Windows Error Reporting operations
level: high
regression_tests_path: regression_data/rules/windows/process_access/proc_access_win_werfaultsecure_msmpeng_access/info.yml
license: DRL-1.1

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