EDRSilencer

Inspired by the closed source FireBlock tool FireBlock from MdSec NightHawk, I decided to create my own version and this tool was created with the aim of blocking the outbound traffic of running EDR processes using Windows Filtering Platform (WFP) APIs.

This tool offers the following features:

• Search known running EDR processes and add WFP filter to block its outbound traffic
• Add WFP filter for a specific process
• Remove all WFP filters created by this tool
• Remove a specific WFP filter by filter id
• Support to run in C2 with in-memory PE execution module (e.g., BruteRatel's memexec)
• Some EDR controls (e.g., minifilter) deny access when a process attempts to obtain a file handle of its EDR processes (e.g., through CreateFileW). However, the FwpmGetAppIdFromFileName0 API, which is used to obtain the FWP app id of the targeted EDR process, calls CreateFileW internally. To avoid this, a custom FwpmGetAppIdFromFileName0 was implemented to construct the app id without invoking CreateFileW, thus preventing unexpected failures when adding a WFP filter to an EDR process