Moonwell - JP_Courses's results

Lines of code

https://github.com/code-423n4/2023-07-moonwell/blob/8694244ebf607a4ed33c0b74f422019fe8eb8d3e/src/core/Oracles/ChainlinkCompositeOracle.sol#L212

Vulnerability details

Impact

The vulnerability in the scalePrice function is related to potential rounding errors in the division operation when scaling prices. Although the contract has overflow protection, it lacks precision protection during division, which can result in inaccurate scaled prices. This occurs because Solidity's integer division behavior truncates the fractional part of the result, leading to incorrect calculations.

Returning a zero price from the oracle could have serious impact on the protocol.

Proof of Concept

price / (10 ** uint256(priceDecimals - expectedDecimals)).toInt256(); = 100 / (10 ** uint256(18 - 2)).toInt256(); = 100 / (10 ** uint256(16)).toInt256(); = 100 / 10000000000000000; = 0;

Tools Used

Manual / VSC.

Recommended Mitigation Steps

To mitigate this vulnerability, fixed-point arithmetic or a library like SafeMath should be used to handle division, ensuring accurate scaling without rounding errors. By using fixed-point arithmetic, fractional numbers can be represented accurately, maintaining precision during arithmetic operations.

Assessed type

Math