Browser Fingerprinting

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For investigators, the ability to move through the digital world without leaving behind identifying traces is critical. Browser fingerprinting is a powerful yet often overlooked tracking method that poses a risk to anonymity. 

Originally developed for advertising and fraud detection, it is increasingly used by websites, including those in the criminal ecosystem, to track visitors.

This article explains how browser fingerprinting works, why it matters to investigators, and what you can do to reduce the risk of exposure.

What Is Browser Fingerprinting

Browser fingerprinting is a technique that builds a unique profile of your device and browser setup using information your system naturally shares when loading websites. Unlike cookies, which can be deleted or blocked, fingerprints are persistent.

Data points commonly collected include:

• Operating system
• Browser type and version
• Installed fonts and plugins
• Screen resolution
• Language preferences
• Graphics card and hardware details
• Device specifications

When combined, these elements form a fingerprint that is unique enough to identify you, even if you use incognito mode, clear cookies, or route traffic through a VPN.

How Fingerprinting Works

Each time you visit a site, scripts silently gather configuration data. Common methods include:

1. JavaScript APIs – Detect fonts, plugins, system language, and display settings.
2. Canvas Fingerprinting – Your browser is asked to render a hidden image; tiny rendering differences reveal unique device traits.
3. Audio Fingerprinting – Analyses how your system processes sound to create another identifier.
4. WebRTC & IP Leaks – Certain protocols can bypass VPNs and expose your true IP address.

Together, these methods allow websites to track you across sessions and domains without leaving obvious traces.

Why Fingerprinting Matters to Investigators

Fingerprinting can undermine anonymity during OSINT or covert monitoring. For example:

• Tracking movements: Websites can identify your returning visits, even under different IPs and when logging in to different accounts. During OSINT investigations, if one of your accounts gets flagged as suspicious, all other covert accounts you have on that platform could also be flagged.

• Raising suspicion: Underground forums you visit as part of your investigation may block accounts or alert users if they detect accounts that have an investigative fingerprint.

• Compromising investigations: A non-standard, uncommon or inconsistent browser fingerprint may stand out, revealing investigative activity instead of blending in with normal users. For instance, if your account on an underground forum purports to be Russian speaking, but your browser fingerprint indicates you use English as your preferred language.

Protecting Yourself Against Fingerprinting

While it’s impossible to completely eliminate your fingerprint, you can make it less distinctive and harder to track.

Use Privacy-Focused Browsers

• Tor Browser: Standardises fingerprints across users, making you blend in.
• Brave: Includes built-in fingerprinting protections.

Control JavaScript: Disabling JavaScript blocks many fingerprinting methods but can break sites. Consider using it selectively.

Adjust Browser Settings: Firefox’s Enhanced Tracking Protection and “resist fingerprinting” mode limit data leaks.

Isolate Activities: Use virtual machines or dedicated browser profiles for separate cases. Prevents a single fingerprint from being tied to all your work.

Investigator Tips

Blend in, don’t stand out: A rare configuration is as risky as being too open. Aim to mimic the “average user.”

Rotate environments: Use different browser profiles or VMs for distinct investigations.

Verify before visiting: Where possible, preview sites using archives (like the Wayback Machine) or passive capture methods before interacting live.

Monitor your own fingerprint: Test against free tools (e.g. AmIUnique.org) to see how identifiable you are.

Conclusion

Browser fingerprinting represents a subtle but powerful way of tracking investigators online. While you cannot eliminate the risk entirely, understanding how it works and applying mitigation strategies ensures you can continue your work without drawing unwanted attention.

In the digital shadows, invisibility is never perfect, but with the right precautions, you can make yourself much harder to detect.