Submission Details
Severity:
The refund function is vulnerable to Reentrancy
Summary
The refund function is vulnerable to a reentrancy attack, as it first transfers the entranceFee and updates the state after.
Vulnerability Details
The refund function looks like this:
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);
}
As we can see, it sends the funds back to the msg.sender and updates the state after that, without using a reentrancy guard. This is vulnerable to a reentrancy attack and therefore allows anyone to fully drain the contract.
Impact
Complete loss of all funds
Tools Used
Manual Review
Recommendations
Use a reentrancy guard, or update the state before the transfer call.
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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