Suspicious Explorer Child Process

Elastic Stack Serverless Security

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 (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[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: 101

Rule authors:

• Elastic

Rule license: Elastic License v2

process where event.type == "start" 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&CKTM

• 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/