being referred discount is calculated wrongly

[code423n4]

Lines of code

https://github.com/code-423n4/2022-12-tigris/blob/main/contracts/Trading.sol#L708-L718
https://github.com/code-423n4/2022-12-tigris/blob/main/contracts/Trading.sol#L786-L792
https://github.com/code-423n4/2022-12-tigris/blob/main/contracts/Trading.sol#L954-L967

Vulnerability details

Impact

If user is referred, referral fees will be sent to the referral and a discount will be deducted on the trading fees of user. However, the amount for the discount is the same as the referral fees in the calculation, causing user to pay lesser fees than they should if they are referred.

Proof of Concept

In handleOpenFees, you can see that if referrer is present, it will mint referralFees for the referrer. The next step is to deduct the referral fees and discount from user fees that they will pay, instead of deducting discount which is 10% of trade fees separately, referralFees is being used instead as the amount for the discount for referred user.

According to https://docs.tigris.trade/protocol/trading-and-fees and https://docs.tigris.trade/protocol/referrals, The discount should be 10% of 0.1% trading fees for commodities and crypto, which is significantly lesser than 0.05% that referrer will get according to the docs. User will pay lesser fees, dao will get lesser fees and therefore GovNFT holders will lose out on fees.

        if (_referrer != address(0)) {
            unchecked {
                IStable(_tigAsset).mintFor(
                    _referrer,
                    _positionSize
                    * _fees.referralFees // get referral fee%
                    / DIVISION_CONSTANT // divide by 100%
                );
            }
            _fees.daoFees = _fees.daoFees - _fees.referralFees*2;
        }

Tools Used

Manual Review

Recommended Mitigation Steps

Few places need to be rewritten to calculate the discount standalone instead of using referral fees as the discount

https://github.com/code-423n4/2022-12-tigris/blob/main/contracts/Trading.sol#L708-L718
https://github.com/code-423n4/2022-12-tigris/blob/main/contracts/Trading.sol#L788-L792
https://github.com/code-423n4/2022-12-tigris/blob/main/contracts/Trading.sol#L954-L967

[c4-judge]

GalloDaSballo marked the issue as duplicate of #542

[c4-judge]

GalloDaSballo marked the issue as satisfactory