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code-423n4 / 2022-01-elasticswap-findings

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swapBaseTokenForQuoteToken and swapQuoteTokenForBaseToken do not check output quantities to be achievable #160

Open code423n4 opened 2 years ago

code423n4 commented 2 years ago

Handle

hyh

Vulnerability details

Impact

Whenever swaps are being run with token amounts too big the system fails with low level not enough amount message from the requested ERC20 token transfer.

Proof of Concept

Both swap functions do not check the amount to be returned:

quoteTokenQty calculated isn't checked to be achievable:

https://github.com/code-423n4/2022-01-elasticswap/blob/main/elasticswap/src/contracts/Exchange.sol#L285

baseTokenQty calculated isn't checked to be achievable:

https://github.com/code-423n4/2022-01-elasticswap/blob/main/elasticswap/src/contracts/Exchange.sol#L323

Recommended Mitigation Steps

Check the amounts to be returned from the quote-to-base and base-to-quote swaps to be lower than current base and quote balance.

0xean commented 2 years ago

Not sure if we will fix this as we have really good error messaging in our SDK and front end, but agree the error messages could be improved.

GalloDaSballo commented 2 years ago

I believe the finding to be valid, because it's at the informational level (error messages), I think non-critical to be more appropriate