Suspicious WerFault Child Process

A suspicious WerFault child process was detected, which may indicate an attempt to run unnoticed. Verify process details such as command line, network connections, file writes and parent process details as well.

Rule type: eql

Rule indices:

winlogbeat-*
logs-endpoint.events.*
logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

Elastic
Host
Windows
Threat Detection
Defense Evasion

Version: 4 (version history)

Added (Elastic Stack release): 7.10.0

Last modified (Elastic Stack release): 7.13.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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Custom Windows error reporting debugger or applications restarted by WerFault after a crash.

Rule query

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process where event.type in ("start", "process_started") and
process.parent.name : "WerFault.exe" and not process.name :
("cofire.exe", "psr.exe",
"VsJITDebugger.exe", "TTTracer.exe",
"rundll32.exe", "LogiOptionsMgr.exe") and not
process.args : ("/LOADSAVEDWINDOWS", "/restore",
"RestartByRestartManager*", "--restarted",
"createdump", "dontsend",
"/watson")

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Masquerading
- ID: T1036
- Reference URL: https://attack.mitre.org/techniques/T1036/

Rule version history

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Version 4 (7.13.0 release)

Updated query, changed from:

event.category:process and event.type:(start or process_started) and
process.parent.name:WerFault.exe and not process.name:(cofire.exe or
psr.exe or VsJITDebugger.exe or TTTracer.exe or rundll32.exe)

Version 3 (7.12.0 release)

Formatting only

Version 2 (7.11.2 release)

Formatting only

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