Submission Details
Severity:
Weak Randomness in searchForEgg() __ EggHuntGame.sol
Summary
Weak Randomness which allows anyone to manipulate the outcome .
Vulnerability Details
This method is vulnerable because both block.timestamp and block.prevrandao are values that can be influenced by miners. Therefore, malicious actors could manipulate these values to generate a favorable outcome (e.g., determining whether they find an egg for a reduced price or with some other advantage).
function searchForEgg() external {
require(gameActive, "Game not active");
require(block.timestamp >= startTime, "Game not started yet");
require(block.timestamp <= endTime, "Game ended");
// Pseudo-random number generation (for demonstration purposes only)
uint256 random = uint256(
keccak256(abi.encodePacked(block.timestamp, block.prevrandao, msg.sender, eggCounter))
) % 100;
if (random < eggFindThreshold) {
eggCounter++;
eggsFound[msg.sender] += 1;
eggNFT.mintEgg(msg.sender, eggCounter);
emit EggFound(msg.sender, eggCounter, eggsFound[msg.sender]);
}
}
Impact
Manipulating the outcome
Tools Used
Manual review
Recommendations
Use Chainlink VRF for Secure Randomness
Updates
Lead Judging Commences
m3dython 10 months ago
Submission Judgement Published Assigned finding tags:
Insecure Randomness
Insecure methods to generate pseudo-random numbers
Rewards breakdown
nSLOC
129This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
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