README.md

Solidity CTFs

This repository contains my solutions to several Solidity & EVM based CTFs and challenges.

• Ethernaut | My Writeups
  • (1) Fallback
  • (2) Fallout
  • (3) CoinFlip
  • (4) Telephone
  • (5) Token
  • (6) Delegation
  • (7) Force
  • (8) Vault
  • (9) King
  • (10) Reentrancy
  • (11) Elevator
  • (12) Privacy
  • (13) Gatekeeper One
  • (14) Gatekeeper Two
  • (15) Naught Coin
  • (16) Preservation
  • (17) Recovery
  • (18) Magic Number
  • (19) Alien Codex
  • (20) Denial
  • (21) Shop
  • (22) Dex One
  • (23) Dex Two
  • (24) Puzzle Wallet
  • (25) Motorbike
  • (26) Double Entry Point
  • (27) Good Samaritan
  • (28) Gatekeeper Three
• QuillCTF | My Writeups
  • (1) Road Closed
  • (2) VIP Bank
  • (3) Confidential Hash
  • (4) Safe NFT
  • (5) D31eg4t3
  • (6) Collatz Puzzle
  • (7) True XOR
  • (8) Pelusa
• EVM Puzzles | My Writeups
  • (*) Puzzles
• More EVM Puzzles | My Writeups
  • (*) More Puzzles

Usage

Just yarn to install required packages (or npm install). Then, you can do any of the following:

• yarn compile to compile the contracts.
• yarn test to run all the challenges. You can pass in --grep <regex> option to run specific tests, such as:
  • yarn test --grep Ethernaut runs all Ethernaut tests.
  • yarn test --grep "QuillCTF 1" runs the 1st challenge of QuillCTF.
  • yarn test --grep "Delegation" runs the Delegation challenge of Ethernaut. If there are multiple challenges with the same name, all will run.
• yarn lint to lint TypeScript.
• yarn node:start to start a Hardhat node on localhost.
• yarn node:run <path> to run a script at the given path on localhost.

Solving a new CTF

Put your tests under the test folder, put the contracts within contracts folder and put your write-ups under docs folder. I prefer having a separate folder for each CTF. You can also find some utility functions under utils folder, such as increasing the block-time, reading storage slots, or setting the balance of an account.

Each test has the following format:

describe('<ctf name> <number>: <challenge name>', () => {
  // accounts
  let owner: SignerWithAddress;
  let attacker: SignerWithAddress;

  // contracts
  let contract: SomeContract; // types via typechain

  // constants
  const CONSTRUCTOR_ARG = '0xBEEF';

  // pre-hack setups
  before(async () => {
    [owner, attacker] = await ethers.getSigners();
    contract = await ethers.getContractFactory('SomeContract', owner).then(f => f.deploy(CONSTRUCTOR_ARG));
  });

  // the pawnage commences
  it('should hack the contract', async () => {});

  // post-hack checks
  after(async () => {
    expect(attacker.address).to.be.properAddress;
    expect(true).to.be.true;
  });
});

If your test requires directly changing the balance of an account, make sure you reset the balance after the tests.