ConvexStakingWrapper.sol after shutdown，rewards can be steal

[code423n4]

Lines of code

https://github.com/reserve-protocol/protocol/blob/e3d2681503499e81915797c77eeef8210352a138/contracts/plugins/assets/convex/vendor/ConvexStakingWrapper.sol#L296

Vulnerability details

Impact

After shutdown, checkpoints are stopped, leading to possible theft of rewards.

Proof of Concept

ConvexStakingWrapper No more checkpoints after shutdown, i.e. no updates reward.reward_integral_for[user]

    function _beforeTokenTransfer(
        address _from,
        address _to,
        uint256
    ) internal override {
@>      _checkpoint([_from, _to]);
    }

    function _checkpoint(address[2] memory _accounts) internal nonReentrant {
        //if shutdown, no longer checkpoint in case there are problems
@>      if (isShutdown()) return;

        uint256 supply = _getTotalSupply();
        uint256[2] memory depositedBalance;
        depositedBalance[0] = _getDepositedBalance(_accounts[0]);
        depositedBalance[1] = _getDepositedBalance(_accounts[1]);

        IRewardStaking(convexPool).getReward(address(this), true);

        _claimExtras();

        uint256 rewardCount = rewards.length;
        for (uint256 i = 0; i < rewardCount; i++) {
            _calcRewardIntegral(i, _accounts, depositedBalance, supply, false);
        }
    }    

This would result in, after shutdown, being able to steal rewards by transferring tokens to new users

Example: Suppose the current reward.reward_integral = 1000

When a shutdown occurs

1. alice transfers 100 to the new user, bob. Since bob is the new user and _beforeTokenTransfer()->_checkpoint() is not actually executed Result. balanceOf[bob] = 100 reward.reward_integral_for[bob] = 0

2. bob executes claimRewards() to steal the reward reward amount = balanceOf[bob] (reward.reward_integral - reward.reward_integral_for[bob]) = 100 (1000-0)

3. bob transfers the balance to other new users, looping steps 1-2 and stealing all rewards

Tools Used

Recommended Mitigation Steps

Still execute _checkpoint

    function _checkpoint(address[2] memory _accounts) internal nonReentrant {
        //if shutdown, no longer checkpoint in case there are problems
 -      if (isShutdown()) return;

        uint256 supply = _getTotalSupply();
        uint256[2] memory depositedBalance;
        depositedBalance[0] = _getDepositedBalance(_accounts[0]);
        depositedBalance[1] = _getDepositedBalance(_accounts[1]);

        IRewardStaking(convexPool).getReward(address(this), true);

        _claimExtras();

        uint256 rewardCount = rewards.length;
        for (uint256 i = 0; i < rewardCount; i++) {
            _calcRewardIntegral(i, _accounts, depositedBalance, supply, false);
        }
    }    

Assessed type

Context

[c4-judge]

thereksfour marked the issue as primary issue

[c4-sponsor]

pmckelvy1 marked the issue as sponsor confirmed

[c4-sponsor]

pmckelvy1 marked the issue as sponsor acknowledged

[c4-judge]

thereksfour marked the issue as satisfactory

[c4-judge]

thereksfour marked the issue as selected for report