CAPTCHA Tracking: Can it Identify You?

TL;DR

Yes, CAPTCHA solving patterns can be used to track and potentially identify individuals, though it’s complex. Websites use various techniques – IP addresses, browser fingerprints, cookies, and analysing how you solve CAPTCHAs – to build a profile. While not foolproof, this information can create a surprisingly accurate identifier over time. Protecting your privacy involves using different browsers, VPNs, avoiding tracking cookies, and being aware of the data websites collect.

Understanding How CAPTCHA Tracking Works

1. IP Address: Your internet protocol (IP) address is a basic identifier. While it doesn’t pinpoint your exact location, it shows roughly where you are connecting from.
2. Browser Fingerprinting: Websites collect details about your browser and operating system – version, installed plugins, fonts, language settings, etc. This creates a unique ‘fingerprint’. You can check yours at BrowserLeaks.
3. Cookies: Small files websites store on your computer to remember you and your preferences. They’re often used for tracking across sites.
4. CAPTCHA Solving Behaviour: This is the core of the issue. How quickly do you solve CAPTCHAs? Do you make mistakes? What types of CAPTCHAs are easiest or hardest for you? These patterns, combined with other data, can create a unique profile.

Steps to Identify Potential Tracking

1. Check Your Cookies: Most browsers allow you to view and delete cookies. Look in your browser settings (usually under ‘Privacy’ or ‘History’). Be aware that deleting all cookies will log you out of many websites.
2. Use a Privacy-Focused Browser Extension: Extensions like Privacy Badger, uBlock Origin, or Ghostery block trackers and ads. They won’t stop everything but significantly reduce tracking.
3. Review Website Privacy Policies: While often lengthy and complex, privacy policies should outline what data the website collects and how it’s used.

How Websites Use CAPTCHA Data

1. Fraud Detection: CAPTCHAs are primarily for preventing bots. Analysing solving patterns helps identify suspicious activity.
2. Risk Scoring: Websites assign a ‘risk score’ to users based on their behaviour. Unusual or inconsistent CAPTCHA solving can raise your risk score, leading to more challenges or account restrictions.
3. User Profiling: Combining CAPTCHA data with other information (IP address, browser fingerprint) builds a detailed user profile for targeted advertising or security purposes.

Protecting Your Privacy

1. Use a VPN: A Virtual Private Network masks your IP address, making it harder to track your location. Choose a reputable VPN provider with a no-logs policy.
2. Different Browsers for Different Purposes: Use one browser for sensitive activities (banking, email) and another for general browsing. This isolates your data.
3. Regularly Clear Browser Data: Delete cookies, cache, and history periodically.
4. Consider a Privacy-Focused Search Engine: DuckDuckGo doesn’t track your searches.
5. Be Aware of CAPTCHA Types: Some CAPTCHAs (like reCAPTCHA v3) are ‘invisible’ but still collect data about your behaviour. They assess risk without requiring you to click boxes.

Technical Considerations

Websites often use JavaScript to gather browser fingerprinting information. You can view the JavaScript code in your browser’s developer tools (usually accessed by pressing F12). Look for scripts that collect device details or send data to third-party servers.

// Example of a simple script collecting user agent string

var userAgent = navigator.userAgent;

console.log(userAgent); // This sends your browser info to the console (and potentially elsewhere)

While you can’t completely prevent CAPTCHA tracking, understanding how it works and taking proactive steps can significantly reduce your digital footprint.