`MuteAmplifier.rescueTokens()` checks the wrong condition for `muteToken`

[code423n4]

Lines of code

https://github.com/code-423n4/2023-03-mute/blob/4d8b13add2907b17ac14627cfa04e0c3cc9a2bed/contracts/amplifier/MuteAmplifier.sol#L185-L191

Vulnerability details

Impact

There will be 2 impacts.

• The reward system would be broken as the rewards can be withdrawn before starting staking.
• Some rewards would be locked inside the contract forever as it doesn't check totalReclaimed

Proof of Concept

rescueTokens() checks the below condition to rescue muteToken.

else if (tokenToRescue == muteToken) {
    if (totalStakers > 0) {
        require(amount <= IERC20(muteToken).balanceOf(address(this)).sub(totalRewards.sub(totalClaimedRewards)),
            "MuteAmplifier::rescueTokens: that muteToken belongs to stakers"
        );
    }
}

But there are 2 problems.

1. Currently, it doesn't check anything when totalStakers == 0. So some parts(or 100%) of rewards can be withdrawn before the staking period. In this case, the reward system won't work properly due to the lack of rewards.
2. It checks the wrong condition when totalStakers > 0 as well. As we can see here, some remaining rewards are tracked using totalReclaimed and transferred to treasury directly. So we should consider this amount as well.

Tools Used

Manual Review

Recommended Mitigation Steps

It should be modified like the below.

else if (tokenToRescue == muteToken) {
    if (totalStakers > 0) { //should check totalReclaimed as well
        require(amount <= IERC20(muteToken).balanceOf(address(this)).sub(totalRewards.sub(totalClaimedRewards).sub(totalReclaimed)),
            "MuteAmplifier::rescueTokens: that muteToken belongs to stakers"
        );
    }
    else if(block.timestamp <= endTime) { //no stakers but staking is still active, should maintain totalRewards
        require(amount <= IERC20(muteToken).balanceOf(address(this)).sub(totalRewards),
            "MuteAmplifier::rescueTokens: that muteToken belongs to stakers"
        );
    }
}

[c4-judge]

Picodes marked the issue as primary issue

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[c4-judge]

Picodes marked the issue as satisfactory

[c4-judge]

Picodes marked the issue as selected for report