T1MOH - Signature malleability breaks TitlesGraph.sol

[sherlock-admin3]

T1MOH

medium

Signature malleability breaks TitlesGraph.sol

Summary

There are 2 versions of signatures from the same data. Because of that property it is advised to not use signature as unique identificator.
You can read here https://detectors.auditbase.com/signature-malleability-of-evms-ecrecover

Vulnerability Detail

Here you can see that signature is used as unique identifier of performed action. So attacker can use another version of used signature to maliciously perform opposite action. For example if edge was previously acknowledged, then he can unacknowledge it.

    modifier checkSignature(bytes32 edgeId, bytes calldata data, bytes calldata signature) {
        bytes32 digest = _hashTypedData(keccak256(abi.encode(ACK_TYPEHASH, edgeId, data)));
        if (
            !edges[edgeId].to.creator.target.isValidSignatureNowCalldata(digest, signature)
                || _isUsed[keccak256(signature)]
        ) {
            revert Unauthorized();
        }
        _;
@>      _isUsed[keccak256(signature)] = true;
    }

    function acknowledgeEdge(bytes32 edgeId_, bytes calldata data_, bytes calldata signature_)
        external
@>      checkSignature(edgeId_, data_, signature_)
        returns (Edge memory edge)
    {
        return _setAcknowledged(edgeId_, data_, true);
    }

    function unacknowledgeEdge(bytes32 edgeId_, bytes calldata data_, bytes calldata signature_)
        external
@>      checkSignature(edgeId_, data_, signature_)
        returns (Edge memory edge)
    {
        return _setAcknowledged(edgeId_, data_, false);
    }

Impact

Attacker can use another version of used signature to maliciously perform opposite action. For example if edge was previously acknowledged, then he can unacknowledge it.

Code Snippet

https://github.com/sherlock-audit/2024-04-titles/blob/main/wallflower-contract-v2/src/graph/TitlesGraph.sol#L49

Tool used

Manual Review

Recommendation

Use OpenZeppelin's ECDSA library.

Duplicate of #279