Decent - zxriptor's results

Summary

Low-Risk Issues

[L‑01] Users can swap and execute without paying protocol fees

Lines of code

https://github.com/code-423n4/2024-01-decent/blob/main/src/UTB.sol#L108 https://github.com/code-423n4/2024-01-decent/blob/main/src/UTB.sol#L311

Description

As there is no access control modifier on UTB.sol::receiveFromBridge, it can be called by anyone. Both of these functions simply call _swapAndExecute, making them interchangeable in the case of ERC20 swaps. However, it's important to note that UTB.sol::receiveFromBridge does not have a payable modifier, so it cannot be used for Ether-based calls. Additionally, since UTB.sol::receiveFromBridge does not utilize the retrieveAndCollectFees modifier, fees are not collected in this function.

Mitigation steps

Consider adding a modifier to limit access UTB.sol::receiveFromBridge to approved bridge adapters only.

[L‑02] Signature malleability of EVM's ecrecover in collectFees()

Lines of code

https://github.com/code-423n4/2024-01-decent/blob/main/src/UTBFeeCollector.sol#L53

Description

EVM's ecrecover is susceptible to a signature malleability which allows replay attacks. In case of fee increase, users may reuse previous fees by supplying another signature, valid for the supplied constructedHash.

Please see this document for the reference: https://swcregistry.io/docs/SWC-117

Mitigation steps

Consider using recover function from OpenZeppelin ECDSA library: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v4.9/contracts/utils/cryptography/ECDSA.sol

[L‑03] Signature replay due to no protocol controlled variables in hash

Lines of code

https://github.com/code-423n4/2024-01-decent/blob/main/src/UTB.sol#L115C38-L115C68 https://github.com/code-423n4/2024-01-decent/blob/main/src/UTBFeeCollector.sol#L49-L50

Description

In the event of a fee increase, users may continue to use the old fees as long as they submit the same data in the SwapAndExecuteInstructions or BridgeInstructions structures. The reason for this is the absence of parameters in a signed hash that are controlled by the protocol or, specifically, the signer.

Mitigation steps

Consider adding deadline (i.e. timestamp) into FeeStructure struct and check it in the UTBFeeCollector.sol::collectFees function.