ecs_checker

EDNS Client Subnet (ECS) Remote Detection Tool - CVE-2025-40766

This tool checks whether a remote DNS resolver supports EDNS Client Subnet (ECS) — a DNS extension that may expose systems to cache poisoning or information leakage vulnerabilities such as CVE-2025-40766.

🔍 What It Does

• Sends a DNS query with an ECS option
• Detects whether ECS is enabled on the target DNS resolver
• Compatible with both Linux/macOS (Python) and Windows (PowerShell)

💻 Usage (Python)

Install dependencies:

pip3 install -r requirements.txt

Run the script:

python3 ecs_checker.py <DNS_SERVER_IP>

Examples:

python3 ecs_checker.py 1.1.1.1
[-] 1.1.1.1 does NOT support ECS (CLIENT-SUBNET not found).

python3 ecs_checker.py 8.8.8.8
[+] 8.8.8.8 supports ECS (CLIENT-SUBNET found).