Hello Ethernaut – Level 0 Walkthrough

Welcome to the first level of the Ethernaut wargame by OpenZeppelin, designed to teach smart contract security through hands-on hacking.

Challenge Objective

You are given a contract deployed to the blockchain. Your goal is to:

• Interact with the contract using JavaScript in the browser console
• Uncover the password
• Call the authenticate() function with the correct password
• Successfully pass the level

Prerequisites

Before you begin, ensure the following:

• MetaMask is installed and connected
• Test ETH is available (Goerli, Sepolia, etc.)
• Familiarity with using browser DevTools and executing JavaScript commands
• Access to the Ethernaut Game

Getting Started

1. Load the Level

• Navigate to ethernaut.openzeppelin.com
• Select “Hello Ethernaut” from the list of levels
• Click “Get new instance”
• Approve the MetaMask transaction to deploy your personalized challenge contract

Once the contract is deployed, it will inject a global object called contract into your browser console.

Walkthrough – Step by Step

🗒️ Step 1: Follow the Hint Chain

await contract.info()

“You will find what you need in info1().”

await contract.info1()

“Try info2(), but with “hello” as a parameter.”

await contract.info2("hello")

“The property infoNum holds the number of the next info method to call.”

await contract.infoNum()

Returns: BigNumber { value: 42 }

await contract.info42()

“theMethodName is the name of the next method.”

await contract.theMethodName()

Returns: “method7123949”

await contract.method7123949()

“If you know the password, submit it to authenticate().”

🔐 Step 2: Retrieve the Password

await contract.password()

Returns: “ethernaut0”

🔓 Step 3: Authenticate with the Password

await contract.authenticate("ethernaut0")

Wait for the MetaMask transaction to confirm.

✅ Step 4: Submit the Level

Click “Submit instance” in the UI and confirm the MetaMask transaction. Once successful, the level is marked as completed.

💡 What You Learn

• Using await to interact with contracts
• Reading public state variables
• Navigating contract hints
• Understanding how contract functions can guide the user
• Sending transactions using authenticate() function
• The basics of interacting with the Ethereum VM in a real browser context

Concepts Covered

📁 Resources

• Ethernaut Game
• Video Walkthrough