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Suspicious WerFault Child Processedit

A suspicious WerFault child process was detected, which may indicate an attempt to run via the SilentProcessExit registry key manipulation. Verify process details such as command line, network connections and file writes.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-endpoint.events.process-*
  • logs-windows.*
  • endgame-*

Severity: medium

Risk score: 47

Runs every: 5m

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

Maximum alerts per execution: 100

References:

Tags:

  • Domain: Endpoint
  • OS: Windows
  • Use Case: Threat Detection
  • Tactic: Defense Evasion
  • Tactic: Persistence
  • Tactic: Privilege Escalation
  • Data Source: Elastic Endgame
  • Data Source: Elastic Defend

Version: 112

Rule authors:

  • Elastic

Rule license: Elastic License v2

Setupedit

Setup

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define event.ingested and default fallback for EQL rules was not added until version 8.2. Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate event.ingested to @timestamp. For more details on adding a custom ingest pipeline refer - https://www.elastic.co/guide/en/fleet/current/data-streams-pipeline-tutorial.html

Rule queryedit

process where host.os.type == "windows" and event.type == "start" and

  process.parent.name : "WerFault.exe" and

  /* args -s and -t used to execute a process via SilentProcessExit mechanism */
  (process.parent.args : "-s" and process.parent.args : "-t" and process.parent.args : "-c") and

  not process.executable : ("?:\\Windows\\SysWOW64\\Initcrypt.exe", "?:\\Program Files (x86)\\Heimdal\\Heimdal.Guard.exe")

Framework: MITRE ATT&CKTM

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