AWL Bypass with Winrm.vbs and Malicious WsmPty.xsl/WsmTxt.xsl - File — Sigma Rule

Rule metadata and linked tags

Author: Julia Fomina, oscd.community. Source status: test; severity: medium. Source dates: 2020-10-06 / 2022-11-28.

{
  "product": "windows",
  "category": "file_event"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 246af2b141aec22494a3c0974268c961dec1b0109d802b13e9408d640c1f0ce6

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: AWL Bypass with Winrm.vbs and Malicious WsmPty.xsl/WsmTxt.xsl - File
id: d353dac0-1b41-46c2-820c-d7d2561fc6ed
related:
    - id: 074e0ded-6ced-4ebd-8b4d-53f55908119d
      type: derived
status: test
description: Detects execution of attacker-controlled WsmPty.xsl or WsmTxt.xsl via winrm.vbs and copied cscript.exe (can be renamed)
references:
    - https://posts.specterops.io/application-whitelisting-bypass-and-arbitrary-unsigned-code-execution-technique-in-winrm-vbs-c8c24fb40404
author: Julia Fomina, oscd.community
date: 2020-10-06
modified: 2022-11-28
tags:
    - attack.stealth
    - attack.t1216
logsource:
    product: windows
    category: file_event
detection:
    system_files:
        TargetFilename|endswith:
            - 'WsmPty.xsl'
            - 'WsmTxt.xsl'
    in_system_folder:
        TargetFilename|startswith:
            - 'C:\Windows\System32\'
            - 'C:\Windows\SysWOW64\'
    condition: system_files and not in_system_folder
falsepositives:
    - Unlikely
level: medium

Original YAML and metadata in JSON

False positives

• Unlikely

Source references

• https://posts.specterops.io/application-whitelisting-bypass-and-arbitrary-unsigned-code-execution-technique-in-winrm-vbs-c8c24fb40404