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Windows EDRSilencer Execution

Detects the usage of EDRSilencer. Inspired by the closed-source FireBlock tool from MdSec NightHawk, this custom tool was developed to block outbound traffic of running Endpoint Detection and Response (EDR) processes…

Description

Detects the usage of EDRSilencer. Inspired by the closed-source FireBlock tool from MdSec NightHawk, this custom tool was developed to block outbound traffic of running Endpoint Detection and Response (EDR) processes using Windows Filtering Platform (WFP) APIs. Its features include searching for running EDR processes and applying WFP filters to block outbound traffic, adding filters for specific processes, and removing filters either individually or globally. The tool includes a custom implementation to avoid file handle access issues with EDR processes by bypassing the CreateFileW API. It supports a wide range of EDRs, including Microsoft Defender, Carbon Black, SentinelOne, and more, though further testing on various EDRs is recommended. The tool has been tested on Windows 10 and Windows Server 2016, and its usage involves simple commands for blocking or unblocking traffic.

Detection logic

Detection requirements

Platform
ContainersESXiIaaSLinuxmacOSNetwork DevicesWindows

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Known benign triggers

  • Some legitimate administrative tools or security workflows may use similar techniques to block or filter EDR traffic for maintenance or troubleshooting. Verify the context and authorized use before flagging.

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