Browser Hardening: A Step-by-Step Guide
Why Browser Hardening Matters
Your web browser is the most exposed application on your device. It executes untrusted code from every website you visit, stores your browsing history and cookies, and leaks information about your system through browser fingerprinting. Out of the box, most browsers prioritise convenience over privacy. Hardening your browser means adjusting settings and installing extensions to minimise data leakage without breaking your browsing experience.
The goal is not to become invisible, which is practically impossible, but to make mass surveillance and casual tracking significantly harder. A hardened browser raises the cost of tracking you, pushing most trackers to give up and target easier victims.
Choosing Your Base Browser
Firefox is the recommended starting point for browser hardening. It is open source, offers extensive privacy settings, and supports the widest range of privacy extensions. Brave is an excellent alternative that blocks trackers and ads by default, requiring less manual configuration. Avoid Chrome if privacy is a priority, as it is deeply integrated with Google's advertising infrastructure.
Whichever browser you choose, ensure it is always up to date. Browser updates include critical security patches, and running an outdated browser is one of the most dangerous things you can do online, regardless of how well you have configured your privacy settings.
Essential Settings Changes
In Firefox, navigate to Settings then Privacy and Security. Set Enhanced Tracking Protection to Strict mode. Enable the option to delete cookies and site data when Firefox is closed. Disable telemetry by unchecking all options under Firefox Data Collection and Use. Set your default search engine to DuckDuckGo or Startpage.
Disable WebRTC to prevent IP address leaks when using a VPN. In Firefox, navigate to about:config and set media.peerconnection.enabled to false. Disable the Pocket integration by setting extensions.pocket.enabled to false. Consider setting privacy.resistFingerprinting to true, though be aware this can cause minor display issues on some websites.
Essential Extensions
Install uBlock Origin as your primary content blocker. It is open source, lightweight, and blocks trackers, advertisements, and malicious domains using regularly updated filter lists. Enable the default filter lists plus the annoyances lists for a cleaner browsing experience. Do not install other ad blockers alongside uBlock Origin, as they can conflict.
Add the HTTPS Everywhere extension or ensure your browser's HTTPS-Only Mode is enabled to force encrypted connections wherever possible. Consider adding the Skip Redirect extension to bypass tracking redirects, and the ClearURLs extension to strip tracking parameters from URLs automatically.
Managing Cookies and Storage
Configure your browser to block third-party cookies entirely. First-party cookies are necessary for most websites to function, but third-party cookies exist almost exclusively for cross-site tracking. Firefox's Total Cookie Protection isolates cookies per-site automatically when Enhanced Tracking Protection is set to Strict.
Use container tabs in Firefox to isolate different browsing contexts. For example, keep social media in one container, shopping in another, and banking in a third. This prevents Facebook from tracking you across shopping sites and vice versa. The Facebook Container extension automates this for Facebook specifically.
Reducing Your Fingerprint
Browser fingerprinting uses your browser's unique combination of settings, fonts, screen resolution, and hardware to identify you without cookies. Firefox's privacy.resistFingerprinting setting standardises many of these values, making your browser look more like everyone else's. The trade-off is that some websites may look slightly different or behave unexpectedly.
Avoid installing unusual fonts or browser extensions beyond what is recommended here, as each addition makes your fingerprint more unique. Ironically, installing too many privacy extensions can make you more identifiable, not less. Stick to the essentials and resist the temptation to add every privacy tool you find.
Testing Your Configuration
After making these changes, test your browser's privacy using the Electronic Frontier Foundation's Cover Your Tracks tool at coveryourtracks.eff.org. This will show you how unique your browser fingerprint is and whether trackers can follow you across websites. Also test for DNS leaks at dnsleaktest.com to ensure your DNS queries are not bypassing your VPN or encrypted DNS provider.
Revisit these settings periodically, especially after major browser updates, as defaults can change. Browser hardening is not a one-time task but an ongoing practice that evolves alongside the tracking techniques it aims to defeat.
