CTFd Server

A lightweight and extensible Model Context Protocol (MCP) server for interacting with any CTFd instance. This project enables AI tools and automation to authenticate, retrieve challenges, and submit flags through a stable API layer.

Overview

This project acts as a bridge between CTFd and AI-driven systems by providing a unified interface. It supports multiple authentication modes, dynamic base URL control, and FastAPI endpoints for debugging and integration.

The server is validated using the official demo instance at https://demo.ctfd.io.

Features

• Dynamic BASE_URL configuration
• Token and cookie authentication
• Username/password login
• List challenges with optional filtering
• Submit flags programmatically
• Compatible with MCP-based AI tools
• Clean and extensible Python codebase

Installation

Install the MCP server using Python:

git clone https://github.com/YourUser/ctfd-mcp-server.git
cd ctfd-mcp-server
pip install -r requirements.txt

Create your environment configuration:

cp .env.example .env

Edit .env as needed:

BASE_URL=https://demo.ctfd.id
CTFD_TOKEN=
CTFD_COOKIE=

Running the MCP Server

Start the server with Python:

python mcp_server.py

The default FastAPI server runs at:

http://127.0.0.1:8000

Example MCP Configuration

If you are using a client such as Claude Desktop or a compatible MCP host, configure it as follows:

{
  "mcpServers": {
    "ctfd-mcp": {
      "command": "python",
      "args": ["mcp_server.py"],
      "env": {
        "BASE_URL": "https://demo.ctfd.io"
      }
    }
  }
}

Usage/Examples

Set Token

{
  "method": "set_token",
  "params": { "token": "your_token_here" }
}

Get Challanges

{
  "method": "challenges",
  "params": {}
}

Sumbit Flag

{
  "method": "submit_flag",
  "params": {
    "challenge_id": 3,
    "flag": "flag{example_payload}"
  }
}

API Endpoints (FastAPI)

Method	Path	Description
POST	/set_token	Set authentication token
POST	/set_cookie	Set session cookie
POST	/login	Login with credentials
GET	/api/v1/challenges	Retrieve challenges
POST	/api/v1/flags	Submit a flag

Support

For support, email [email protected] or open an issue through the GitHub repository. Community contributions and improvements are always welcome.

License

MIT