/* * @source: https://consensys.github.io/smart-contract-best-practices/known_attacks/ * @author: consensys * @vulnerable_at_lines: 17 */ pragma solidity ^0.5.0; contract Reentrancy_insecure { // INSECURE mapping (address => uint) private userBalances; function withdrawBalance() public { uint amountToWithdraw = userBalances[msg.sender]; // REENTRANCY (bool success, ) = msg.sender.call.value(amountToWithdraw)(""); // At this point, the caller's code is executed, and can call withdrawBalance again require(success); userBalances[msg.sender] = 0; } }