Tapioca DAO - 0xrugpull_detector's results

Lines of code

https://github.com/Tapioca-DAO/tapiocaz-audit/blob/master/contracts/tOFT/modules/BaseTOFTStrategyModule.sol#L152-L162 https://github.com/Tapioca-DAO/tapiocaz-audit/blob/master/contracts/tOFT/modules/BaseTOFTMarketModule.sol#L160-L169 https://github.com/Tapioca-DAO/tapiocaz-audit/blob/master/contracts/tOFT/modules/BaseTOFTOptionsModule.sol#L189-L200 https://github.com/Tapioca-DAO/tapiocaz-audit/blob/master/contracts/tOFT/modules/BaseTOFTLeverageModule.sol#L184-L194 https://github.com/Tapioca-DAO/tapioca-bar-audit/blob/master/contracts/usd0/modules/USDOLeverageModule.sol#L169-L179 https://github.com/Tapioca-DAO/tapioca-bar-audit/blob/master/contracts/usd0/modules/USDOMarketModule.sol#L168-L177 https://github.com/Tapioca-DAO/tapioca-bar-audit/blob/master/contracts/usd0/modules/USDOOptionsModule.sol#L174-L185

Vulnerability details

Proof of Concept

All these contracts are module contracts for omni-chain operations like leverage, strategy, market, options.

Vulnerabiilies come from 2 reasons.

• These module contracts has no access control mechanism in place for important omni-chain related functions.
• These functions delegatecall to any address supplied as modules parameter.

For example, a hacker can call BaseTOFTStrategyModule.strategyDeposit() passing modules as malicious contract with SELFDESTRUCT.

contract MaliciousModule Is Ownable {
    function depositToYieldbox() {
        selfdestruct(owner());
    }
}

contract MaliciousAttacker Is Ownable {
    function attack() {
        BaseTOFTStrategyModule(strategyModule).strategyDeposit(new MaliciousModule(), ...);
    }
}

https://github.com/Tapioca-DAO/tapiocaz-audit/blob/master/contracts/tOFT/modules/BaseTOFTStrategyModule.sol#L152-L162

    function strategyDeposit(
        address module,
        uint16 _srcChainId,
        bytes memory _srcAddress,
        uint64 _nonce,
        bytes memory _payload,
        IERC20 _erc20
    ) public {
        ...

        (bool success, bytes memory reason) = module.delegatecall(// @audit - might cause self destructions, function should not be public
            abi.encodeWithSelector(
                this.depositToYieldbox.selector,
                assetId,
                amount,
                share,
                _erc20,
                address(this),
                onBehalfOf
            )
        );

Impact

Complete DoS of Omni-chain tokens by destroying leverage, strategy, option, market modules.

Tools Used

Manual Review

Recommendation

• There should be access control mechanism for omni-chain feature functions.
• Only trusted modules address should be used for delegatecall.

Assessed type

call/delegatecall

Lines of code

https://github.com/Tapioca-DAO/tapioca-bar-audit/blob/master/contracts/markets/bigBang/BigBang.sol#L191

Vulnerability details

Proof of Concept

BigBang.init() might set non-zero big debtStartPoint value.

https://github.com/Tapioca-DAO/tapioca-bar-audit/blob/master/contracts/markets/bigBang/BigBang.sol#L156-L162

    _isEthMarket = collateralId == penrose.wethAssetId();
    if (!_isEthMarket) {
        debtRateAgainstEthMarket = _debtRateAgainstEth;
        maxDebtRate = _debtRateMax;
        minDebtRate = _debtRateMin;
        debtStartPoint = _debtStartPoint;
    }

If debtStartPoint is greater than totalBorrow.elastic, underflow will occur.

https://github.com/Tapioca-DAO/tapioca-bar-audit/blob/master/contracts/markets/bigBang/BigBang.sol#L180-L201

    function getDebtRate() public view returns (uint256) {
        ...
        uint256 _currentDebt = totalBorrow.elastic;
        uint256 debtPercentage = ((_currentDebt - debtStartPoint) *
            DEBT_PRECISION) / (_maxDebtPoint - debtStartPoint);
        ...

        return debt;
    }

Impact

As getDebtRate() is called by accure() and liquidate(). it will cause these functions to be reverted as well.

https://github.com/Tapioca-DAO/tapioca-bar-audit/blob/master/contracts/markets/bigBang/BigBang.sol#L512-L541

    function _accrue() internal override {
....
        //update debt rate
        uint256 annumDebtRate = getDebtRate();
...
    }

Recommendation

If totalBorrow.elastic < debtStartPoint, getDebtRate() should return mintDebtRate.

    function getDebtRate() public view returns (uint256) {
        ...
        uint256 _currentDebt = totalBorrow.elastic;
+       if (_currentDebt < debtStartPoint) return minDebtRate;
        uint256 debtPercentage = ((_currentDebt - debtStartPoint) *
            DEBT_PRECISION) / (_maxDebtPoint - debtStartPoint);
        ...

        return debt;
    }

Assessed type

DoS

Lines of code

https://github.com/Tapioca-DAO/tapioca-yieldbox-strategies-audit/blob/master/contracts/yearn/YearnStrategy.sol#L145

Vulnerability details

It is quite possible for some times Yearn strategy might return incurring losses.

As maxLoss parameter is set to 0, YearnStrategy._withdraw() does not tolerate any losses incurred.

It will make withdrawal from Yearn strategies blocked.

    function _withdraw(
        address to,
        uint256 amount
    ) internal override nonReentrant {
        uint256 available = _currentBalance();
        require(available >= amount, "YearnStrategy: amount not valid");

        uint256 queued = wrappedNative.balanceOf(address(this));
        if (amount > queued) {
            uint256 pricePerShare = vault.pricePerShare();
            uint256 toWithdraw = (((amount - queued) *
                (10 ** vault.decimals())) / pricePerShare);

            vault.withdraw(toWithdraw, address(this), 0); // @audit - maxLoss = 0
        }
        wrappedNative.safeTransfer(to, amount - 1); //rounding error

        emit AmountWithdrawn(to, amount);
    }

Impact

Withdrawal might be blocked in case of strategy loss.

Recommendation

It should use maxLoss parameter which is updatable by owner.

https://github.com/Tapioca-DAO/tapioca-yieldbox-strategies-audit/blob/master/contracts/yearn/YearnStrategy.sol#L145

    function _withdraw(
        address to,
        uint256 amount
    ) internal override nonReentrant {
        uint256 available = _currentBalance();
        require(available >= amount, "YearnStrategy: amount not valid");

        uint256 queued = wrappedNative.balanceOf(address(this));
        if (amount > queued) {
            uint256 pricePerShare = vault.pricePerShare();
            uint256 toWithdraw = (((amount - queued) *
                (10 ** vault.decimals())) / pricePerShare);

-           vault.withdraw(toWithdraw, address(this), 0);
+           vault.withdraw(toWithdraw, address(this), maxLoss);
        }
        wrappedNative.safeTransfer(to, amount - 1);

        emit AmountWithdrawn(to, amount);
    }

Assessed type

DoS