Evercookie: A Persistent Tracking Mechanism

Published on: 2024-08-10 18:29:56

Evercookie is a JavaScript technique that creates persistent identifiers in a browser. This article explains how Evercookie works, its value for tracking users, its limits, and what users can do to protect themselves.

What is an Evercookie?

An Evercookie is a tracking method that writes the same value to multiple storage mechanisms in a user’s browser. Unlike regular cookies, Evercookies are difficult to remove and can restore themselves after deletion.

How Does Evercookie Work?

Storing Data in Multiple Places: Evercookie writes the same value to several browser storage options, including standard HTTP cookies, Local Shared Objects, and HTML5 storage.
Rebuilding Mechanism: If one location is cleared, Evercookie reads the remaining copies to recreate the missing ones.
Persistent Tracking: This redundancy and rebuilding logic enable long-term user tracking.

Value of Evercookie for Tracking

Evercookie supports tracking because of its:

Persistence: Copies can remain after deletion attempts.
Cross-Session Tracking: It can link activity across multiple browsing sessions.
Resistance to Blocking: Traditional cookie blockers may not cover all storage paths Evercookie uses.

Limitations of Evercookie

Privacy Concerns: Its persistence can be invasive.
Regulatory Restrictions: Some jurisdictions restrict or regulate persistent tracking technologies.
Browser Support: Not all browsers expose every storage mechanism Evercookie relies on.

Protecting Against Evercookie

You can reduce exposure to Evercookie by:

Using Privacy-focused Browsers: Tor or browsers with strict privacy settings can reduce these traces.
Disabling Flash and Other Plugins: Disable plugins that expose additional storage vectors.
Regularly Clearing Browser Data: Clear cookies and other storage mechanisms on a regular schedule.

Conclusion

Evercookie enables persistent tracking and creates real privacy risks. Understanding how it works, and applying protective measures, helps you keep control of your browsing data and privacy.

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