sigmamediumHunting

Creation of WerFault.exe/Wer.dll in Unusual Folder

Detects the creation of a file named "WerFault.exe" or "wer.dll" in an uncommon folder, which could be a sign of WerFault DLL hijacking.

MITRE ATT&CK

T1574.001

privilege-escalationpersistencedefense-evasion

Detection Query

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\arm64\
condition: selection and not 1 of filter_main_*

Author

frack113

Created

2022-05-09

Data Sources

windowsFile Events

Platforms

windows

References

https://www.bleepingcomputer.com/news/security/hackers-are-now-hiding-malware-in-windows-event-logs/

Tags

attack.privilege-escalationattack.persistenceattack.defense-evasionattack.t1574.001

Raw Content

title: Creation of WerFault.exe/Wer.dll in Unusual Folder
id: 28a452f3-786c-4fd8-b8f2-bddbe9d616d1
status: test
description: Detects the creation of a file named "WerFault.exe" or "wer.dll" in an uncommon folder, which could be a sign of WerFault DLL hijacking.
references:
    - https://www.bleepingcomputer.com/news/security/hackers-are-now-hiding-malware-in-windows-event-logs/
author: frack113
date: 2022-05-09
modified: 2025-12-03
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.defense-evasion
    - 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\arm64\'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium