Submission Details
Severity:
PuppyRaffle::selectWinner the RNG is deterministic
Summary
The RNG at PuppyRaffle.selectWinner()
uint256 winnerIndex = uint256(keccak256(abi.encodePacked(msg.sender, block.timestamp, block.difficulty))) % players.length; is deterministic because the hash can be predetermined, so the winnerIndex is also deterministic.
Vulnerability Details
Impact
severity : high
likelihood : high
Tools Used
manual review
Recommendations
Implement Chainlink's VRFv2 to implement randomness / determining the winnerIndex.
Updates
Lead Judging Commences
Hamiltonite almost 2 years 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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