Submission Details
Severity:
The reentrancy vulnerability in refund can allow an attacker to steal all funds
Summary
PuppyRaffle#refund has a sendValue function that calls msg.sender to send back the entry fee and set the player addresses in the player array to zero addresses. However, msg.sender can call the fallback() function to reenter refunds().
Vulnerability Details
function refund(uint256 playerIndex) public {
address playerAddress = players[playerIndex];
require(playerAddress == msg.sender, "PuppyRaffle: Only the player can refund");
require(playerAddress != address(0), "PuppyRaffle: Player already refunded, or is not active");
payable(msg.sender).sendValue(entranceFee);
players[playerIndex] = address(0);
emit RaffleRefunded(playerAddress);
}
Impact
An attacker can maliciously reenter refund() to steal all the funds.
Tools Used
Manual Review
Recommendations
Consider using ReentrancyGuard or the checks-effects-interactions pattern
Updates
Lead Judging Commences
Hamiltonite about 2 years ago
Submission Judgement Published Assigned finding tags:
reentrancy-in-refund
reentrancy in refund() function
Rewards breakdown
nSLOC
143This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
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