SaharDevep - Stale or incorrect price return from Chainlink's latestRoundData

[sherlock-admin]

SaharDevep

medium

Stale or incorrect price return from Chainlink's latestRoundData

SaharDevep

Medium

Stale or incorrect collateral price return from Chainlink's latestRoundData

Summary

latestRoundData is used, but there is no check to see if the returned value indicates stale data.

Vulnerability Detail

in StableOracleDAI.sol:
    (, int256 price, , , ) = priceFeedDAIETH.latestRoundData();
        // @audit Not enough checks
        return
            (wethPriceUSD * 1e18) /
            ((DAIWethPrice + uint256(price) * 1e10) / 2);

in StableOracleWBTC.sol:
        // @audit Not enough checks
        (, int256 price, , , ) = priceFeed.latestRoundData();
        // chainlink price data is 8 decimals for WETH/USD
        return uint256(price) * 1e10;

in StableOracleWETH.sol:
        // @audit Not enough checks
        (, int256 price, , , ) = priceFeed.latestRoundData();
        // chainlink price data is 8 decimals for WETH/USD
        return uint256(price) * 1e10;

Impact

This could lead to stale prices according to the Chainlink documentation:
https://docs.chain.link/data-feeds/price-feeds/historical-data
Related report:
sherlock-audit/2023-02-blueberry-judging#94

Code Snippet

https://github.com/sherlock-audit/2023-05-USSD/blob/6d7a9fdfb1f1ed838632c25b6e1b01748d0bafda/ussd-contracts/contracts/oracles/StableOracleDAI.sol#L48
https://github.com/sherlock-audit/2023-05-USSD/blob/6d7a9fdfb1f1ed838632c25b6e1b01748d0bafda/ussd-contracts/contracts/oracles/StableOracleWBTC.sol#L23
https://github.com/sherlock-audit/2023-05-USSD/blob/6d7a9fdfb1f1ed838632c25b6e1b01748d0bafda/ussd-contracts/contracts/oracles/StableOracleWETH.sol#L23

Tool used

Manual Review

Recommendation

Consider adding these checks:

        (uint80 roundID, int256 price, uint256 timestamp, uint256 updatedAt, ) = priceFeed.latestRoundData();
        require(updatedAt >= roundID, "Stale price");
        require(timestamp != 0,"Round not complete");
        require(answer > 0,"Chainlink answer reporting 0");

        if (updatedAt < block.timestamp - maxDelayTime)
            revert();

        // now return price

Duplicate of #31