Suspicious Execution via Windows Subsystem for Linux

Detects Linux Bash commands from the Windows Subsystem for Linux. Adversaries may enable and use WSL for Linux to avoid detection.

Rule type: eql

Rule indices:

winlogbeat-*
logs-endpoint.events.*
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:

Elastic
Host
Windows
Threat Detection
Execution
Defense Evasion
Elastic Endgame

Version: 1

Rule authors:

Elastic

Rule license: Elastic License v2

Rule query

edit

process where event.type : "start" and
 (
  ((process.executable : "?:\\Windows\\System32\\bash.exe" or process.pe.original_file_name == "Bash.exe") and
  not process.command_line : ("bash", "bash.exe")) or
  process.executable : "?:\\Users\\*\\AppData\\Local\\Packages\\*\\rootfs\\usr\\bin\\bash" or
  (process.parent.name : "wsl.exe" and process.parent.command_line : "bash*" and not process.name : "wslhost.exe") or
  (process.name : "wsl.exe" and process.args : ("curl", "/etc/shadow", "/etc/passwd", "cat","--system", "root", "-e", "--exec", "bash", "/mnt/c/*"))
  ) and
  not process.parent.executable : ("?:\\Program Files\\Docker\\*.exe", "?:\\Program Files (x86)\\Docker\\*.exe")

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Indirect Command Execution
- ID: T1202
- Reference URL: https://attack.mitre.org/techniques/T1202/
Tactic:
- Name: Execution
- ID: TA0002
- Reference URL: https://attack.mitre.org/tactics/TA0002/
Technique:
- Name: Command and Scripting Interpreter
- ID: T1059
- Reference URL: https://attack.mitre.org/techniques/T1059/
Sub-technique:
- Name: Unix Shell
- ID: T1059.004
- Reference URL: https://attack.mitre.org/techniques/T1059/004/

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