Submission Details
Severity:
block.prevrandao not available in solidity 0.8.13
Summary
The .prevrandao method is not available on the version of solidity used in the contract. The functionaly will not work as expected when drawing a card. This impacts the entirely gameflow as a result.
Vulnerability Details
// Generate a random index
uint256 randomIndex = uint256(
keccak256(
abi.encodePacked(block.timestamp, msg.sender, block.prevrandao)//@audit - what is prevrandao???
)
) % availableCards[player].length;
Impact
No randomness means the drawcard function and entire game can be gamed. Risk of total loss of funds for the contract.
Tools Used
Manual Review
Recommendations
Implement an alternative form of pseudo-randomness.
Updates
Lead Judging Commences
inallhonesty 11 months ago
Submission Judgement Published Assigned finding tags:
`block.prevrandao` usage fails with pragmas below 0.8.18
Rewards breakdown
nSLOC
147This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
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