IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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Suspicious Explorer Child Process

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Suspicious Explorer Child Process

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Identifies a suspicious Windows explorer child process. Explorer.exe can be abused to launch malicious scripts or executables from a trusted parent process.

Rule type: eql

Rule indices:

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

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: None

Tags:

Elastic
Host
Windows
Threat Detection
Initial Access

Version: 8

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

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## 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 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.

Rule query

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process where event.type in ("start", "process_started") and
  (
   process.name : ("cscript.exe", "wscript.exe", "powershell.exe", "rundll32.exe", "cmd.exe", "mshta.exe", "regsvr32.exe") or
   process.pe.original_file_name in ("cscript.exe", "wscript.exe", "PowerShell.EXE", "RUNDLL32.EXE", "Cmd.Exe", "MSHTA.EXE", "REGSVR32.EXE")
  ) and
  /* Explorer started via DCOM */
  process.parent.name : "explorer.exe" and process.parent.args : "-Embedding" and
  not process.parent.args:
          (
            /* Noisy CLSID_SeparateSingleProcessExplorerHost Explorer COM Class IDs   */
            "/factory,{5BD95610-9434-43C2-886C-57852CC8A120}",
            "/factory,{ceff45ee-c862-41de-aee2-a022c81eda92}"
          )

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Initial Access
- ID: TA0001
- Reference URL: https://attack.mitre.org/tactics/TA0001/
Technique:
- Name: Phishing
- ID: T1566
- Reference URL: https://attack.mitre.org/techniques/T1566/
Sub-technique:
- Name: Spearphishing Attachment
- ID: T1566.001
- Reference URL: https://attack.mitre.org/techniques/T1566/001/
Sub-technique:
- Name: Spearphishing Link
- ID: T1566.002
- Reference URL: https://attack.mitre.org/techniques/T1566/002/

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