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One World
NFTDeFi
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Submission Details
Severity: low
Valid

EIP712Base and NativeMetaTransaction's domain separator breaks in case of a hardfork.

inh3l

Summary

EIP712Base's and NativeMetaTransaction's domain separator is set in the constructor which makes signatures generated from it vulnerable to replay attacks during a hardfork. As per EIP712, calculating the domain separator using a hardcoded chainId could pose problems as a hardfork changes the chain's chain id, the domain separator will be inaccurately calculated.

Vulnerability Details

NativeMetaTransaction is EIP712Base which sets the domain seperator in the constructor.

constructor(
string memory name,
string memory version
){
_setDomainSeperator(name, version);
}

This sets the domain seperator which can no longer be changed.

function _setDomainSeperator(string memory name, string memory version) internal {
domainSeperator = keccak256(
abi.encode(
EIP712_DOMAIN_TYPEHASH,
keccak256(bytes(name)),
keccak256(bytes(version)),
address(this),
bytes32(getChainId())
)
);
}

The cached domainSeperator is then used to derive the message hash in the toTypedMessageHash function.

function toTypedMessageHash(bytes32 messageHash)
internal
view
returns (bytes32)
{
return
keccak256(
abi.encodePacked("\x19\x01", getDomainSeperator(), messageHash)
);
}

This will have an effect on signature verification as it can be replayed to execute meta transactions.

function verify(
address signer,
MetaTransaction memory metaTx,
bytes32 sigR,
bytes32 sigS,
uint8 sigV
) internal view returns (bool) {
require(signer != address(0), "NativeMetaTransaction: INVALID_SIGNER");
return
signer ==
ecrecover(
toTypedMessageHash(hashMetaTransaction(metaTx)),
sigV,
sigR,
sigS
);
}

Impact

In case of a hardfork, signatures are vulnerable to replays.

Tools Used

Manual Review

Recommendations

Calculate the domain separator everytime its needed rather than using the cached domainSeperator parameter.

Updates

Lead Judging Commences

0xbrivan2 Lead Judge 12 months ago
Submission Judgement Published
Invalidated
Reason: Incorrect statement

Appeal created

0xbrivan2 Lead Judge 11 months ago
Submission Judgement Published
Validated
Assigned finding tags:

can't update domainSeparator in case of hard fork

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