Asymmetry contest - Polaris_tow's results

Lines of code

https://github.com/code-423n4/2023-03-asymmetry/blob/44b5cd94ebedc187a08884a7f685e950e987261c/contracts/SafEth/SafEth.sol#L63-L100 https://github.com/code-423n4/2023-03-asymmetry/blob/44b5cd94ebedc187a08884a7f685e950e987261c/contracts/SafEth/SafEth.sol#L108-L129

Vulnerability details

Impact

The SafEth contract does not allow users to submit a deadline for their action. This missing feature enables pending transactions to be maliciously executed at a later point.

Proof of Concept

The SafEth contract should provide their users with an option to limit the execution of their pending actions,such as stake and unstake functions.The most common solution is to include a deadline timestamp as a parameter (for example see Uniswap V2). If such an option is not present, users can unknowingly perform bad trades.

    function stake() external payable {
        require(pauseStaking == false, "staking is paused");
        require(msg.value >= minAmount, "amount too low");
        require(msg.value <= maxAmount, "amount too high");


        uint256 underlyingValue = 0;


        // Getting underlying value in terms of ETH for each derivative
        for (uint i = 0; i < derivativeCount; i++)
            underlyingValue +=
                (derivatives[i].ethPerDerivative(derivatives[i].balance()) *
                    derivatives[i].balance()) /
                10 ** 18;


        uint256 totalSupply = totalSupply();
        uint256 preDepositPrice; // Price of safETH in regards to ETH
        if (totalSupply == 0)
            preDepositPrice = 10 ** 18; // initializes with a price of 1
        else preDepositPrice = (10 ** 18 * underlyingValue) / totalSupply;


        uint256 totalStakeValueEth = 0; // total amount of derivatives worth of ETH in system
        for (uint i = 0; i < derivativeCount; i++) {
            uint256 weight = weights[i];
            IDerivative derivative = derivatives[i];
            if (weight == 0) continue;
            uint256 ethAmount = (msg.value * weight) / totalWeight;


            // This is slightly less than ethAmount because slippage
            uint256 depositAmount = derivative.deposit{value: ethAmount}();
            uint derivativeReceivedEthValue = (derivative.ethPerDerivative(
                depositAmount
            ) * depositAmount) / 10 ** 18;
            totalStakeValueEth += derivativeReceivedEthValue;
        }
        // mintAmount represents a percentage of the total assets in the system
        uint256 mintAmount = (totalStakeValueEth * 10 ** 18) / preDepositPrice;
        _mint(msg.sender, mintAmount);
        emit Staked(msg.sender, msg.value, mintAmount);
    }

The way this function calculates mintAmount is by calculating the eth price of each derivative, so it is more easily affected by time.The transaction is submitted to the mempool, however, Alice chose a transaction fee that is too low for miners to be interested in including her transaction in a block. The transaction stays pending in the mempool for extended periods, which could be hours, days, weeks, or even longer.Especially when the price change is relatively large, the impact is greater. Had the same submission in a previous contest:https://github.com/Uniswap/v2-periphery/tree/master/contracts

Tools Used

vscode

Recommended Mitigation Steps

Introduce a deadline parameter to the mentioned functions.