Lines of code

https://github.com/code-423n4/2022-03-volt/blob/f1210bf3151095e4d371c9e9d7682d9031860bbd/contracts/vcon/Vcon.sol#L110-L117

Vulnerability details

Impact

The setMinter() function in Vcon.sol lacks both zero address checks and a proper ownership transfer pattern. I am submitting this as a medium-severity issue separate from similar low-severity instances due to this example's effect on the entire protocol. If the minter is set incorrectly due to human error or a malicious actor, VCON will not be able to be minted ever again.

Proof of Concept

The following code illustrates the setMinter() function.

    function setMinter(address minter_) external {
        require(
            msg.sender == minter,
            "Vcon: only the minter can change the minter address"
        );
        emit MinterChanged(minter, minter_);
        minter = minter_;
    }

It is clear that this function does not check that _minter != address(0). Similarly, if _minter is input incorrectly, either an unknown address or non-existent address will be set as the minter. Since only the minter can set a new minter, the minting functionality will be lost forever.

Tools Used

Manual review.

Recommended Mitigation Steps

A proper ownership transfer pattern would be helpful to eliminate all risks outlined above. The steps to achieve:

changeMinter() function sets a variable pendingNewMinter = _minter
acceptMinter() function must be called by pendingNewMinter for the minter to be fully set.

code-423n4 / 2022-03-volt-findings