Some signatures are not supported

[code423n4]

Lines of code

https://github.com/code-423n4/2023-01-biconomy/blob/53c8c3823175aeb26dee5529eeefa81240a406ba/scw-contracts/contracts/smart-contract-wallet/paymasters/verifying/singleton/VerifyingSingletonPaymaster.sol#L107-L108

Vulnerability details

Impact

The VerifyingSingletonPaymaster intends to support compact signatures . This is known due to the line below :-

        require(sigLength == 64 || sigLength == 65, "VerifyingPaymaster: invalid signature length in paymasterAndData");

This contract is using Openzeppelin ECDSA library for verifying the signatures.
Since, this PR , openzeppelin has stopped support for compact signatures for some functions in its library .

Since 4.7.3

Breaking changes

• ECDSA: recover(bytes32,bytes) and tryRecover(bytes32,bytes) no longer accept compact signatures to prevent malleability. Compact signature support remains available using recover(bytes32,bytes32,bytes32) and tryRecover(bytes32,bytes32,bytes32).

VerifyingSingletonPaymaster uses recover(bytes32,bytes) for both 64 length and 65 length signatures.
Hence all 64 length signatures will fail , even though the protocol wants to support them .

Proof of Concept

OpenZeppelin/openzeppelin-contracts#3610

Tools Used

Manual

Recommended Mitigation Steps

Use recover(bytes32,bytes32,bytes32) or tryRecover(bytes32,bytes32,bytes32) if you want to support both 64 and 65 length signatures. Also, use nonce if you want to prevent signature malleability .

[c4-judge]

gzeon-c4 marked the issue as duplicate of #194

[c4-sponsor]

livingrockrises marked the issue as sponsor confirmed

[c4-judge]

gzeon-c4 changed the severity to QA (Quality Assurance)

[c4-judge]

gzeon-c4 marked the issue as grade-c