smartbugs-curated/dataset/access_control/wallet_02_refund_nosub.sol

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/*
* @source: https://smartcontractsecurity.github.io/SWC-registry/docs/SWC-105#wallet-02-refund-nosubsol
* @author: -
* @vulnerable_at_lines: 36
*/
pragma solidity ^0.4.24;
/* User can add pay in and withdraw Ether.
Unfortunately the developer forgot set the user's balance to 0 when refund() is called.
An attacker can pay in a small amount of Ether and call refund() repeatedly to empty the contract.
*/
contract Wallet {
address creator;
mapping(address => uint256) balances;
constructor() public {
creator = msg.sender;
}
function deposit() public payable {
assert(balances[msg.sender] + msg.value > balances[msg.sender]);
balances[msg.sender] += msg.value;
}
function withdraw(uint256 amount) public {
require(amount <= balances[msg.sender]);
msg.sender.transfer(amount);
balances[msg.sender] -= amount;
}
function refund() public {
// <yes> <report> ACCESS_CONTROL
msg.sender.transfer(balances[msg.sender]);
}
// In an emergency the owner can migrate allfunds to a different address.
function migrateTo(address to) public {
require(creator == msg.sender);
to.transfer(this.balance);
}
}