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One World
NFTDeFi
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Submission Details
Severity: medium
Valid

NativeMetaTransaction.executeMetaTransaction() failed txs are open to replay attacks

xmanuel

Summary

https://github.com/Cyfrin/2024-11-one-world/blob/1e872c7ab393c380010a507398d4b4caca1ae32b/contracts/meta-transaction/NativeMetaTransaction.sol#L65

Vulnerability Details

Any transactions that fail based on some conditions that may change in the future are not safe to be executed again later (e.g. transactions that are based on others actions, or time-dependent etc).

In the current implementation, once the low-level call is failed, the whole tx will be reverted and so that nonces[userAddress] will remain unchanged.

As a result, the same tx can be replayed by anyone, using the same signature.

https://github.com/Cyfrin/2024-11-one-world/blob/1e872c7ab393c380010a507398d4b4caca1ae32b/contracts/meta-transaction/NativeMetaTransaction.sol#L65

​
function executeMetaTransaction(
address userAddress,
bytes memory functionSignature,
bytes32 sigR,
bytes32 sigS,
uint8 sigV
) public payable returns (bytes memory) {
MetaTransaction memory metaTx = MetaTransaction({
nonce: nonces[userAddress],
from: userAddress,
functionSignature: functionSignature
});
​
require(
verify(userAddress, metaTx, sigR, sigS, sigV),
"Signer and signature do not match"
);
​
// increase nonce for user (to avoid re-use)
nonces[userAddress] = nonces[userAddress] + 1;
​
emit MetaTransactionExecuted(
userAddress,
msg.sender,
functionSignature,
hashMetaTransaction(metaTx)
);
​
// Append userAddress and relayer address at the end to extract it from calling context
(bool success, bytes memory returnData) = address(this).call{value: msg.value}(
abi.encodePacked(functionSignature, userAddress)
);
require(success, "Function call not successful");
​
return returnData;
}

Impact

Replay Attacks: Attackers can reuse signatures if the nonce remains unchanged after a failed transaction.

Tools Used

manual

Recommendations

Failed txs should still increase the nonce.

While implementating the change above, consider adding one more check to require sufficient gas to be paid, to prevent "insufficient gas griefing attack" as described in this article.

Updates

Lead Judging Commences

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

Appeal created

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

failed meta transactions are replayable

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