heroui logo

AWL Bypass with Winrm.vbs and Malicious WsmPty.xsl/WsmTxt.xsl

Sigma Rules

View Source
Summary
This detection rule identifies a potential application whitelisting bypass technique involving the execution of attacker-controlled XSL files (WsmPty.xsl or WsmTxt.xsl) through the WinRM (Windows Remote Management) script (winrm.vbs). The rule aims to detect instances where the command line includes specific formatting options while invoking WinRM, particularly when the script is run using a renamed version of 'cscript.exe'. This behavior indicates possible malicious activity as it suggests the use of external scripts that can manipulate processes to bypass standard application whitelisting protections. The detection conditions are structured to flag instances where 'winrm' is present in the command line, combined with formatting arguments that are not sourced from the system directory, thus indicating a potential attack stemming from an unauthorized source.
Categories
  • Endpoint
  • Windows
Data Sources
  • Process
Created: 2020-10-06