AtomWallet does not fully respect ERC-4337 standard

[hats-bug-reporter[bot]]

Github username: -- Twitter username: @burnerelu Submission hash (on-chain): 0x0f336c0e954ad4133dff4950831ca5d667b42939442ee9ffca1dff0b77507a94 Severity: low

Description: Description\ ERC-4337 states the following: "(The account) .. MUST validate the signature is a valid signature of the userOpHash, and SHOULD return SIG_VALIDATION_FAILED (and not revert) on signature mismatch. Any other error MUST revert." (https://eips.ethereum.org/EIPS/eip-4337).

In the current AtomWallet implementation, the error return value of the ECDSA.tryRecover function is not checked. This way, regardless of the error signaled by the tryRecover function, the _validateSignature implementation will not revert.

Attack Scenario\ Not applicable

Attachments

1. Proof of Concept (PoC) File

validateSigOriginal.sol - contains the function that does not respect the ERC-4337 standard

2. Revised Code File (Optional) validateSigProposal.sol - contains two versions of the modified function - one that treats all ECDSA error types in a similar fashion and reverts using a generic error, and one that reverts with specific error types that also take errorArg into account.

A third option would be to call ECDSA.recover instead of ECDSA.tryRecover, as it is done in example https://github.com/eth-infinitism/account-abstraction/blob/develop/contracts/samples/SimpleAccount.sol

Files:

• validateSigProposal.sol (https://hats-backend-prod.herokuapp.com/v1/files/QmavGXVDbExrNaFRb66fCX7HvCoY8j8RvXtytR9EqxMD9T)
• validateSigOriginal.sol (https://hats-backend-prod.herokuapp.com/v1/files/QmZ6yAGWfCjD5LRCzaMgzJaQ2U2928tDSs5Z2DorpvurdF)

[mihailo-maksa]

Our detailed perspective:

• Please paste the code files directly here instead of providing download links for easier review and validation.
• The proposed fix should address cases where the signature is invalid, not just where there is a mismatch. Specifically, the _validateSignature function should be updated to check the error return value of the ECDSA.tryRecover function and revert accordingly if the signature is invalid.
• To comply with the ERC-4337 standard, our implementation will ensure that the validation of the signature results in SIG_VALIDATION_FAILED when there is a mismatch, while any other error must cause a revert.
• In conclusion, we acknowledge this as a minor issue and will implement the necessary changes to ensure full compliance with the ERC-4337 standard, enhancing the robustness of our contract's signature validation process.