ctf-builder 0.0.4

Tool for building CTFs

🚩 CTF Builder

A tool to build, test, and deploy CTFs.

📥 Installation

📦 Requirements

• Docker

🐍 PIP

System-wide:

pip install ctf-builder

venv:

python -m venv .venv
source .venv/bin/activate
pip install ctf-builder

⚙️ Usage

All tools are available through the ctf executable. Documentation can found in the help menu.

ctf -h

Note: use the environment variable CTF=/path/to/ctf if the command is not being run inside a CTF package.

Have a look at the sample CTF for the structure of a CTF package.

📔 Documentation

ctf doc

Provides the JSON schema for challenge.json. This is automatically generated from schema.py.

🎨 Schema

ctf schema

Validates challenge.json. Provides what type is expected and a useful comment for fields.

🔨 Build

ctf build

Builds challenge static files. This is useful for challenges that requires compiling binaries, making assets, etc. Instead of uploading the artifacts part of the repository they can stay separate.

🧪 Test

ctf test

Checks that solve scripts produce the provided flag. This is useful to validate that the challenge logic.

🌱 Environment Variables

The automatic testing provides the following environment variables to solve scripts.

CHALLENGE_ID - the challenge offset inside 'challenges' array.
CHALLENGE_HOST - deploy only: the challenge host name.
CHALLENGE_PORT - deploy only: the challenge port.

FLAG - the value of the flag to test.
FLAG_TYPE - the type of flag to test (static, regex).

☁️ Deploy

ctf start
ctf stop

Deploys challenges to their containerized environment. This is useful for network-based challenges.

🔌 Ports

Exposed/public ports DO NOT match the host port. This is to prevent collisions between challenges. Each challenge is allocated 5 public ports. These ports are assigned to challenges alphabetically, so if a has 1-5 then b will 6-10 etc. Integrations will make sure handle this. Ports can also be determined through Docker.

docker container ls

🌐 Multi-deployment

Challenges can be deployed on multiple virtual hosts. This can be used to provide every team their own infrastructure.

Setup Hosts

Determine the IP range and interface for the network.

ip addr

Let's assume this is eth0 and 192.168.0.0/24. New IPs can be added for the number of infrastructures.

sudo ip addr add 192.168.0.2/24 dev eth0
sudo ip addr add 192.168.0.3/24 dev eth0
...

Deploy

The infrastructures can be deployed as follows.

ctf start --network team1 --ip 192.168.0.2 --network team2 --ip 192.168.0.3 ...

The shorthand version can also be used.

ctf start -n team1 -i 192.168.0.2 -n team2 -i 192.168.0.3 ...

🚩 CTFd

ctf ctfd init
ctf ctfd deploy teams
ctf ctfd deploy challenges

CTFd is supported out of the box. This allows to automate deploying challenges.

Usage

Easiest way to get started is to run the Docker container for CTFd.

docker run -p 8000:8000 -it ctfd/ctfd

The CTF can be initialized from the ctfd/setup.json.

ctf ctfd init -p ADMIN_PASSWORD

An access token is needed to make more changes. It should have the ctfd_... format.

http://localhost:8000/settings > Access Tokens > Generate

Teams can be added through ctfd/teams.json. A ctfd/teams.out.json will generated with the teams/users credentials.

ctf ctfd deploy teams -k ctfd_...

Challenges can be deploy as follows.

ctf ctfd deploy challenges -k ctfd_...