Backd Tokenomics contest - codexploder's results

Lines of code

https://github.com/code-423n4/2022-05-backd/blob/main/protocol/contracts/tokenomics/AmmGauge.sol#L103

Vulnerability details

Impact

Staking is not stopped even when Gauge is killed. User will not be getting any reward for the staked asset.

Proof of Concept

1. Assume the AMMGauge is killed using kill function (AmmGauge.sol#L49). This sets killed as true

2. poolCheckpoint will not further increase ammStakedIntegral and would simply return false

function poolCheckpoint() public virtual override returns (bool) {
        if (killed) {
            return false;
        }
		...
		}

3. User calls stakeFor function and is still able to stake amount.

4. The drawback will be no rewards as poolCheckpoint will only return false and will not update ammStakedIntegral

Recommended Mitigation Steps

Add below check in stakeFor function, restricting deposit if Gauge is killed

require(!killed, "Gauge killed");