Submission Details
Severity:
Validators can choose the winner
Description
In RapBattle::goOnStageOrBattle, the winner is decided using the random variable which uses block.timestamp, block.prevrandao, and msg.sender to be random. The problem is that validators can slightly move these variables during block validation. A malicious validator is able to manipulate the randomness and choose a winner.
uint256 random = uint256(
keccak256(
@> abi.encodePacked(block.timestamp, block.prevrandao, msg.sender)
)
) % totalBattleSkill;
Risk
Likelyhood: Low
Only validators can manipulate the randomness.
Impact: High
Validors are able to manipulate the randomness and choose a winner.
Recommended Mitigation
Use an oracle like Chainlink to obtain real randomness.
Updates
Lead Judging Commences
inallhonesty almost 2 years ago
Submission Judgement Published Assigned finding tags:
Weak Randomness
Rewards breakdown
nSLOC
201This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
Live
The contest is live. Earn rewards by submitting a finding.
Appeals
This is your time to appeal against judgements on your submissions.
Appeals Review
Appeals are being carefully reviewed by our judges.