Chainlink's latestRoundData might return stale or incorrect results

[code423n4]

Handle

nikitastupin

Vulnerability details

Proof of Concept

https://github.com/code-423n4/2021-10-mochi/blob/8458209a52565875d8b2cefcb611c477cefb9253/projects/mochi-cssr/contracts/adapter/ChainlinkAdapter.sol#L49

The ChainlinkAdapter calls out to a Chainlink oracle receiving the latestRoundData(). If there is a problem with Chainlink starting a new round and finding consensus on the new value for the oracle (e.g. Chainlink nodes abandon the oracle, chain congestion, vulnerability/attacks on the chainlink system) consumers of this contract may continue using outdated stale or incorrect data (if oracles are unable to submit no new round is started).

Recommended Mitigation Steps

Add the following checks:

...
( roundId, rawPrice, , updateTime, answeredInRound ) = AggregatorV3Interface(XXXXX).latestRoundData();
require(rawPrice > 0, "Chainlink price <= 0");
require(updateTime != 0, "Incomplete round");
require(answeredInRound >= roundId, "Stale price");
...

References

• https://consensys.net/diligence/audits/2021/09/fei-protocol-v2-phase-1/#chainlinkoraclewrapper-latestrounddata-might-return-stale-results
• Should check return data from Chainlink aggregators 2021-05-fairside-findings#70