Taiko - 0xleadwizard's results

Lines of code

https://github.com/code-423n4/2024-03-taiko/blob/main/packages/protocol/contracts/team/TimelockTokenPool.sol#L168-L172

Vulnerability details

Impact

A signature replay attack is possible, which leads to the withdrawal of user funds.

Proof of Concept

function withdraw(address _to, bytes memory _sig) external {
        if (_to == address(0)) revert INVALID_PARAM();
        bytes32 hash = keccak256(abi.encodePacked("Withdraw unlocked Taiko token to: ", _to));
        address recipient = ECDSA.recover(hash, _sig);
        _withdraw(recipient, _to);
    }

No nonce is used in the hash

Flow of the attack:

1. Grant is approved to A
2. A allows B to withdraw by signing the hash
3. B withdraws on behalf of A
4. A gets a New grant approved
5. B uses the same previous sig, to withdraw all A funds again!

Recommended Mitigation Steps

A nonce should be used while constructing hash.

Assessed type

Invalid Validation