EDRSilencer: A Tool for Managing EDR Outbound Traffic with Windows Filtering Platform.

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)

The tool currently supports the following EDRs:

Microsoft Defender for Endpoint and Microsoft Defender Antivirus
Elastic EDR
Trellix EDR
Qualys EDR
SentinelOne
Cylance
Cybereason
Carbon Black EDR
Carbon Black Cloud
Tanium
Palo Alto Networks Traps/Cortex XDR
FortiEDR
Cisco Secure Endpoint (Formerly Cisco AMP)
ESET Inspect
Harfanglab EDR
TrendMicro Apex One

As I do not have access to all these EDRs for testing, please do not hesitate to correct me if the listed processes (edrProcess in EDRSilencer.c) prove insufficient in blocking all alert, detection, or event forward traffic.

Testing Environment

Tested in Windows 10 and Windows Server 2016

Usage

Usage: EDRSilencer.exe <blockedr/block/unblockall/unblock>
- Add WFP filters to block the IPv4 and IPv6 outbound traffic of all detected EDR processes:
  EDRSilencer.exe blockedr

- Add WFP filters to block the IPv4 and IPv6 outbound traffic of a specific process (full path is required):
  EDRSilencer.exe block "C:\Windows\System32\curl.exe"

- Remove all WFP filters applied by this tool:
  EDRSilencer.exe unblockall

- Remove a specific WFP filter based on filter id:
  EDRSilencer.exe unblock <filter id>

Compile

x86_64-w64-mingw32-gcc EDRSilencer.c -o EDRSilencer.exe -lfwpuclnt utils.c

Example

Detect and block the outbound traffic of running EDR processes

EDRSilencer.exe blockedr

Varshini

Varshini is a Cyber Security expert in Threat Analysis, Vulnerability Assessment, and Research. Passionate about staying ahead of emerging Threats and Technologies.