Submission Details
Severity:
`Battle` event emits wrong winner in one case
Summary
In the RapBattle contract the Battle event emits the challanger as the winner when the calculated random number equals to the defenderRapperSkill however in this case the real winner is the defender.
Vulnerability Details
RapBattle::_battle Line 67-77:
@> emit Battle(msg.sender, _tokenId, random < defenderRapperSkill ? _defender : msg.sender);
// If random <= defenderRapperSkill -> defenderRapperSkill wins, otherwise they lose
@> if (random <= defenderRapperSkill) {
// We give them the money the defender deposited, and the challenger's bet
credToken.transfer(_defender, defenderBet);
credToken.transferFrom(msg.sender, _defender, _credBet);
} else {
// Otherwise, since the challenger never sent us the money, we just give the money in the contract
credToken.transfer(msg.sender, _credBet);
}
The conditional statements in the two highlighted lines are different.
Impact
dApps that relies on this event can gets incorrect winner.
Tools Used
Manual review
Recommendations
Use the correct condition in the event.
- emit Battle(msg.sender, _tokenId, random < defenderRapperSkill ? _defender : msg.sender);
+ emit Battle(msg.sender, _tokenId, random <= defenderRapperSkill ? _defender : msg.sender);
// If random <= defenderRapperSkill -> defenderRapperSkill wins, otherwise they lose
if (random <= defenderRapperSkill) {
// We give them the money the defender deposited, and the challenger's bet
credToken.transfer(_defender, defenderBet);
credToken.transferFrom(msg.sender, _defender, _credBet);
} else {
// Otherwise, since the challenger never sent us the money, we just give the money in the contract
credToken.transfer(msg.sender, _credBet);
}
Updates
Lead Judging Commences
inallhonesty almost 2 years ago
Submission Judgement Published Assigned finding tags:
Contradictory battle result event
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.