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code-423n4 / 2022-04-backd-findings

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`_decimalMultiplier` doesn't account for tokens with decimals higher than 18 #49

Open code423n4 opened 2 years ago

code423n4 commented 2 years ago

Lines of code

https://github.com/code-423n4/2022-04-backd/blob/c856714a50437cb33240a5964b63687c9876275b/backd/contracts/strategies/StrategySwapper.sol#L287-L289 https://github.com/code-423n4/2022-04-backd/blob/c856714a50437cb33240a5964b63687c9876275b/backd/contracts/strategies/StrategySwapper.sol#L318-L320 https://github.com/code-423n4/2022-04-backd/blob/c856714a50437cb33240a5964b63687c9876275b/backd/contracts/strategies/StrategySwapper.sol#L335-L337

Vulnerability details

Impact

In StrategySwapper, swapping from or to tokens with decimals higher than 18 will always revert. This will cause inabilities for strategies to harvest rewards.

Proof of Concept

L288 will revert when token_ has higher than 18 decimals.

 return 10**(18 - IERC20Full(token_).decimals());

Recommended Mitigation Steps

Consider modifying how _decimalMultiplier works so it could handle tokens with higher than 18 decimals.

Update the calculation of _minTokenAmountOut and _minWethAmountOut to account when decimals are higher/lower than 18.

chase-manning commented 2 years ago

https://github.com/backdfund/protocol/pull/290