Submission Details
Severity:
Uniqueness of hash for `rarity` can be broken, could be same `msg.sender` and same block difficulty used more than once.
Summary
Uniqueness of hash for rarity can be broken, could be same msg.sender and same block difficulty used more than once.
Vulnerability Details
Impact
Effectively two or more winners could end up with the same rarity NFTs not due to random coincidence, but purely due to the bad uniqueness factor being used.
Tools Used
VSC.
Recommendations
Suggest to add additional parameters that would help increase the uniqueness factor:
uint256 rarity = uint256(keccak256(abi.encodePacked(msg.sender, block.difficulty, block.timestamp, nonce))) % 100;
Updates
Lead Judging Commences
Hamiltonite over 1 year ago
Submission Judgement Published Assigned finding tags:
weak-randomness
Root cause: bad RNG Impact: manipulate winner
Rewards breakdown
nSLOC
143This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
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