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Suspicious Execution via Windows Subsystem for Linuxedit

Detects Linux Bash commands from the 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:

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

Version: 4

Rule authors:

  • Elastic

Rule license: Elastic License v2

Rule queryedit

process where host.os.type == "windows" and 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&CKTM

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