Submission Details
Severity:
Randomness vulnerabilities
Summary
The function selectWinner has a randomness vulnerability.
Vulnerability Details
Each transaction on Ethereum has a deterministic state. Using timestamp and block difficulty to generate random numbers is not appropriate
Impact
block.timestamp and block.diffulty are used to choose a winner. We can manipulate the selection of the winner because both method are not good enough to generate random numbers
Tools Used
Manual review
Recommendations
Do not use block.timestamp or blockhash as a source of randomness. Instead, use oracle such as chainlink
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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