Beedle - Oracle free perpetual lending

Summary

The ISwapRouter.ExactInputSingleParams() in the Fees.sol contract sets the amountOutMinimum to zero, which makes it prone to sandwich attacks.

Vulnerability Details

The “0” here is the value of the amountOutMinimum argument which is used for slippage tolerance. 0 value here essentially means 100% slippage tolerance. This is a very easy target for MEV and bots to do a flash loan sandwich attack on each of the strategy’s swaps, resulting in a very big slippage on each trade.
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Impact

100% slippage tolerance can be exploited in a way that the fees receive will be much less value than they should have been. This can be done on every trade if the trade transaction goes through a public mempool.

Tools Used

manual review

Recommendations

A Good solution would be for the developers to set the slippage to a strict amount where the swaps would revert if such an attack is performed on it.