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Oracle.getUnderlyingPrice could have wrong decimals #44

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code423n4 opened this issue Feb 21, 2022 · 2 comments
Open

Oracle.getUnderlyingPrice could have wrong decimals #44

code423n4 opened this issue Feb 21, 2022 · 2 comments
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2 (Med Risk) Assets not at direct risk, but function/availability of the protocol could be impacted or leak value bug Something isn't working disagree with severity Sponsor confirms validity, but disagrees with warden’s risk assessment (sponsor explain in comments) sponsor confirmed Sponsor agrees this is a problem and intends to fix it (OK to use w/ "disagree with severity")

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@code423n4
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Lines of code

https://github.com/code-423n4/2022-02-hubble/blob/8c157f519bc32e552f8cc832ecc75dc381faa91e/contracts/Oracle.sol#L34

Vulnerability details

Impact

The Oracle.getUnderlyingPrice function divides the chainlink price by 100.
It probably assumes that the answer for the underlying is in 8 decimals but then wants to reduce it for 6 decimals to match USDC.

However, arbitrary underlying tokens are used and the chainlink oracles can have different decimals.

Recommended Mitigation Steps

While most USD price feeds use 8 decimals, it's better to take the on-chain reported decimals into account by doing AggregatorV3Interface(chainLinkAggregatorMap[underlying]).decimals(), see Chainlink docs.
The price should then be scaled down to 6 decimals.
@code423n4 code423n4 added 3 (High Risk) Assets can be stolen/lost/compromised directly bug Something isn't working labels Feb 21, 2022
code423n4 added a commit that referenced this issue Feb 21, 2022
@code423n4
cmichel issue #44
cea6ede
@atvanguard atvanguard added disagree with severity Sponsor confirms validity, but disagrees with warden’s risk assessment (sponsor explain in comments) sponsor confirmed Sponsor agrees this is a problem and intends to fix it (OK to use w/ "disagree with severity") labels Feb 24, 2022
@atvanguard
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atvanguard commented Feb 24, 2022 •
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All chainlink USD pairings are expected to have 8 decimals hence disagreeing with severity; but yes agree that asserting this check when adding a new asset is a good idea.

@moose-code
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Downgrading to medium. Dividing by magic numbers (100) should clearly comment assumptions

@moose-code moose-code added 2 (Med Risk) Assets not at direct risk, but function/availability of the protocol could be impacted or leak value and removed 3 (High Risk) Assets can be stolen/lost/compromised directly labels Mar 6, 2022
@sherlock-admin sherlock-admin mentioned this issue Jul 3, 2023
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2 (Med Risk) Assets not at direct risk, but function/availability of the protocol could be impacted or leak value bug Something isn't working disagree with severity Sponsor confirms validity, but disagrees with warden’s risk assessment (sponsor explain in comments) sponsor confirmed Sponsor agrees this is a problem and intends to fix it (OK to use w/ "disagree with severity")
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