Windows: Winrm.vbs AWL bypass using attacker WsmPty.xsl/WsmTxt.xsl

Detects WinRM vbs execution with suspicious XSL formatting arguments, especially when the binary is outside System32/SysWOW64.

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windows-winrm-vbs-awl-bypass-using-attacker-wsmpty-xsl-wsmtxt-xsl-074e0ded

title: "Windows: Winrm.vbs AWL bypass using attacker WsmPty.xsl/WsmTxt.xsl"
id: 7e86b012-6480-474a-9512-6250586677ae
status: test
description: This rule flags suspicious process creation where the command line includes WinRM execution via winrm.vbs and references XSL formatting arguments indicative of payload use. It further narrows matches to cases where the executing binary is not located in the Windows System32/SysWOW64 directories, reducing benign signed-system execution likelihood. Telemetry relies on Windows process creation fields, specifically Image path and CommandLine content.
references:
  - https://posts.specterops.io/application-whitelisting-bypass-and-arbitrary-unsigned-code-execution-technique-in-winrm-vbs-c8c24fb40404
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_winrm_awl_bypass.yml
author: Julia Fomina, oscd.community, Huntrule Team
date: 2020-10-06
modified: 2022-10-09
tags:
  - attack.stealth
  - attack.t1216
logsource:
  category: process_creation
  product: windows
detection:
  contains_format_pretty_arg:
    CommandLine|contains:
      - format:pretty
      - format:"pretty"
      - format:"text"
      - format:text
  image_from_system_folder:
    Image|startswith:
      - C:\Windows\System32\
      - C:\Windows\SysWOW64\
  contains_winrm:
    CommandLine|contains: winrm
  condition: contains_winrm and (contains_format_pretty_arg and not image_from_system_folder)
falsepositives:
  - Unlikely
level: medium
license: DRL-1.1
related:
  - id: 074e0ded-6ced-4ebd-8b4d-53f55908119d
    type: derived

What it detects

This rule flags suspicious process creation where the command line includes WinRM execution via winrm.vbs and references XSL formatting arguments indicative of payload use. It further narrows matches to cases where the executing binary is not located in the Windows System32/SysWOW64 directories, reducing benign signed-system execution likelihood. Telemetry relies on Windows process creation fields, specifically Image path and CommandLine content.

Known false positives

Unlikely

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