Windows PowerShell Command Lines Containing [char]0x or (WCHAR)0x Obfuscation Syntax

Identifies PowerShell execution command lines using suspicious [char]0x or (WCHAR)0x encoding patterns.

FreeUnreviewedSigmahighv1

windows-powershell-command-lines-containing-char-0x-or-wchar-0x-obfuscation-synt-e312efd0

title: Windows PowerShell Command Lines Containing [char]0x or (WCHAR)0x Obfuscation Syntax
id: e9f97d72-a21f-4da4-b38a-c2164f09f4b5
status: test
description: This rule flags Windows process creation events where a PowerShell command line contains encoded character syntax patterns such as "[char]0x" or "(WCHAR)0x". Attackers commonly use these representations to obscure payload content and reduce readability for analysts and simple string-based detections. Detection relies on process creation telemetry and matching these specific substrings in the command line.
references:
  - https://twitter.com/0gtweet/status/1281103918693482496
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_powershell_obfuscation_via_utf8.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2020-07-09
modified: 2025-03-03
tags:
  - attack.execution
  - attack.stealth
  - attack.t1059.001
  - attack.t1027
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    CommandLine|contains:
      - "[char]0x"
      - (WCHAR)0x
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: e312efd0-35a1-407f-8439-b8d434b438a6
    type: derived

What it detects

This rule flags Windows process creation events where a PowerShell command line contains encoded character syntax patterns such as "[char]0x" or "(WCHAR)0x". Attackers commonly use these representations to obscure payload content and reduce readability for analysts and simple string-based detections. Detection relies on process creation telemetry and matching these specific substrings in the command line.

Known false positives

Unknown

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.