Hack This Site: Can You Breach the Vault?

Hack This Site - Complete Solution

Step 1: Understanding the Challenge

When you open the challenge, you see a login form for a vault system called "SecureVault". The form asks for a username and password. If you try random credentials, you'll see an error message: "Invalid credentials. Access denied."

The key insight here is that this is a client-side application - all the HTML, CSS, and JavaScript are loaded in your browser. This means the authentication logic must be somewhere in the JavaScript code.

Step 2: Opening Browser Developer Tools

To analyze the JavaScript code, you'll need to use your browser's developer tools. These built-in tools allow you to inspect HTML, view JavaScript source code, set breakpoints, and debug web applications.

Step 3: Locating the JavaScript Code

Now we need to find where the JavaScript code is located in the page.

Step 4: Analyzing the Obfuscated Code Structure

Let's examine what we can see in the obfuscated code:

Step 5: Deobfuscating Hex-Encoded Strings

The easiest way to understand the obfuscated code is to decode the hex-encoded strings:

Step 6: Finding the Credentials

By examining the code structure and decoding hex strings, you'll discover the authentication logic:

function validateAccess() {
    var username = document.getElementById('username').value;
    var password = document.getElementById('password').value;
    
    if (username.toLowerCase() == 'admin' && password == '7f3a9c2e1b5d8f4a') {
        // Store authentication state
        authState = password;
        grantAccess(username, password);
    } else {
        showError();
    }
}

Step 7: Accessing the Restricted Area (Primary Method)

Now that you have the valid credentials, you can authenticate normally:

Step 8: Understanding the Authentication Flow

After successful authentication, here's what happens internally:

Step 9: Analyzing the Flag Retrieval Mechanism

The retrieveFlag() function has built-in security to prevent easy bypasses:

function retrieveFlag(username, password) {
    // Check authentication state and password
    if (!authState || password != storedPassword) {
        return 'Access Denied';
    }
    
    // Decode the flag from character codes
    var encoded = '102,52,97,52,100,101,97,56,45,99,51,100,53,45,52,100,48,55,45,56,50,52,100,45,50,52,97,97,50,97,48,100,102,56,101,101';
    return encoded.split(',').map(function(code) {
        return String.fromCharCode(parseInt(code, 10));
    }).join('');
}

Step 10: Alternative Bypass Methods (Require Credentials)

Even with security measures, you can still bypass the normal flow - but you MUST have the credentials first:

Step 11: Retrieving the Final Flag

After successfully authenticating (or using one of the bypass methods), the flag will be displayed:

Key Security Lessons

Tools and Techniques Summary

Real-World Applications

This type of vulnerability is commonly found in:

• Administrative panels: Internal tools with weak authentication that should have server-side validation
• Single-page applications: SPAs that implement auth logic incorrectly in JavaScript
• Mobile app web views: Hybrid apps using web technologies without proper backend security
• API key exposure: Hardcoded API keys, tokens, or secrets in frontend code
• Premium feature unlocks: Client-side checks for paid features that can be bypassed
• Development/staging environments: Forgotten debug code or hardcoded credentials in production
• Embedded systems: IoT devices with web interfaces and client-side authentication

Bug bounty programs regularly reward findings of hardcoded credentials, exposed API keys, and client-side authentication bypasses. Typical bounty amounts range from $500 to $5,000 depending on severity and impact. Understanding these vulnerabilities is essential for both offensive security testing and defensive secure development.

Prevention and Mitigation