DownUnderCTF / eth-challenge-infra

The infrastructure that is used for DownUnderCTF blockchain challenges

Eth CTF Challenge V2

This is the infrastructure that can runs an individual ETH CTF challenge for an individual player. Manages challenge lifecycle, player account creation, flag management and the blockchain itself. Web UI to interact with the challenge.

Heavily inspired by https://github.com/chainflag/solidctf. The backend API is written in Typescript and supports 1 Chain, 1 Challenge, and 1 Team, at a time.

Contains a containerized blockchain node which can be used to deploy contracts onto however it is not required and you can point the deployment to any ethereum RPC endpoint

Built for DownUnderCTF.

Usage

Example Challenge

To get up and running with straight away with the example challenge connecting to a local geth blockchain:

docker compose up

Access the API at http://localhost:3000 and the chain RPC url at http://localhost:8545.

I just want to run a challenge

The easiest way to get up and running with your own challenge is to use the published docker image downunderctf/eth-base and copy your contract files and compiled ABI as well as your challenge.yaml as shown in the example folder. Then ensure that your environment variables are set correctly

The environemnt variables that are configurable for the API are:

Variable	Description	DEFAULT
BLOCKCHAIN_RPC_URL	The JSON RPC endponit to connect to	http://localhost:8545
DEPLOYER_PRIVATE_KEY	The private key for the deployer address that you want to use	35d7e3183bbe3e89907724a7c50a1e3f7207af30d169812534558f3591e27b30
CONFIG_FILE_NAME	The filename of the challenge configuration	challenge.yaml

The challenge.yaml file is where the configuration of your challenge will live

challenge_name: "Solve Me" 
challenge_description: "you gonna be solving this challenge alright"
setup_contract_name: "SetupSolveMe" # This is the name of the contract that should deploy your challenge and check if it is complete. It should inherit the Setup.sol contract
flag: "DUCTF{MA_NAME_JEFF_grace_epic}"

# Optional flags
player_initial_balance: 2 # in ether
# enable_faucet: false
challenge_source_files: # Source files to provide to the player
  - "SolveMe.sol"

Dev

There are 3 distinct components to this repository

1. src/ contains the backend API code which handles interations with the blockchain and managing the challenge state.
2. ui/ contains the react frontend code which players interact with for challenge administration.
3. geth/ is the containerized ethereum node which allows configuration of the blockchain itself.

Geth Setup

cd geth/
docker compose up 

The environment variables that are configurable are:

Variable	Description	DEFAULT
BLOCK_TIME	How often a block is mined in seconds (use 0 for on demand mining)	1
DEPLOYER_PRIVATE_KEY	The private key for the deployer address that you want to use	35d7e3183bbe3e89907724a7c50a1e3f7207af30d169812534558f3591e27b30
CHAIN_ID	The chain's id	31337