Windows: WerFault.exe/wer.dll File Creation in Uncommon Locations

Alerts on newly created WerFault.exe or wer.dll in non-standard locations, suggesting potential DLL hijacking activity.

FreeReviewedSigma · Medium · v2

Product: windows
Category: file_event
Author: frack113 (SigmaHQ), DRL 1.1
Published: 2022-05-09
Updated: 2026-07-31

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1574.001DLL
Persistence
- T1574.001DLL
Priv Esc
- T1574.001DLL
Defense Evasion
- T1574.001DLL
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags the creation of files named WerFault.exe or wer.dll when they appear in locations other than common Windows system directories. Attackers may use these binaries for DLL hijacking or related persistence to execute malicious code under trusted Windows paths. It relies on Windows file creation telemetry that includes the full target path and the creating process image, and it excludes events where the creating process ends with wuaucltcore.exe.

Reporting behind it

Related detections9 linkedT1574.001 — drag to rearrange

Suspicious DLL Sideloading via msdtc oci.dll Install (via process_creation)

Suspicious wmicodegen.dll Sideload by inetinfo.exe (UAT-8099 Cobalt Strike)

Suspicious LucidRook DismCore.dll Side-Load into Browser Process

Suspicious Encrypted Implant File Creation for DLL Search Order Hijacking (RainyDay Turian PlugX)

Suspicious RoboForm Signed Binary Executed From Non-Standard Path (via process_creation)

Malicious dal_keepalives.dll Sideloaded By Signed Binary (via image_load)

Suspicious Cortex XDR Binary Sideloading winutils.dll (via image_load)

Suspicious CoinLoader DLL Sideload From Z-1-36-81 Directory (via image_load)

Suspicious shfolder.dll Sideloading via VMware net-service Binary

Windows: WerFault.exe/wer.dll File Creation in Uncommon Locations

Pivot detection · T1574.001 · 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-werfault-exe-wer-dll-created-in-uncommon-directory-28a452f3

title: "Windows: WerFault.exe/wer.dll File Creation in Uncommon Locations"
id: 7e45ff87-cf72-4fd3-93d6-8d80eef36805
status: test
description: This rule flags the creation of files named WerFault.exe or wer.dll when they appear in locations other than common Windows system directories. Attackers may use these binaries for DLL hijacking or related persistence to execute malicious code under trusted Windows paths. It relies on Windows file creation telemetry that includes the full target path and the creating process image, and it excludes events where the creating process ends with wuaucltcore.exe.
references:
  - https://www.bleepingcomputer.com/news/security/hackers-are-now-hiding-malware-in-windows-event-logs/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_event/file_event_win_werfault_dll_hijacking.yml
author: frack113, Huntrule Team
date: 2022-05-09
modified: 2026-05-18
tags:
  - attack.privilege-escalation
  - attack.persistence
  - attack.execution
  - attack.stealth
  - attack.t1574.001
logsource:
  product: windows
  category: file_event
detection:
  selection:
    TargetFilename|endswith:
      - \WerFault.exe
      - \wer.dll
  filter_main_known_locations:
    TargetFilename|startswith:
      - C:\Windows\SoftwareDistribution\
      - C:\Windows\System32\
      - C:\Windows\SysWOW64\
      - C:\Windows\WinSxS\
      - C:\Windows\UUS\
  filter_main_process:
    Image|endswith: \wuaucltcore.exe
  condition: selection and not 1 of filter_main_*
falsepositives:
  - Unknown
level: medium
license: DRL-1.1
related:
  - id: 28a452f3-786c-4fd8-b8f2-bddbe9d616d1
    type: derived

Convert

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

SplunkSPL