Table of Contents
Evercookie
Unlike standard cookies, which can be erased through browser settings, Evercookie regenerates itself by pulling data from various storage methods, ensuring continuous tracking of users even if they clear their browsing history or cookies.
What is an Evercookie?
Evercookie is a JavaScript-based tracking method that takes advantage of multiple client-side storage mechanisms to store persistent data. It was originally developed as a proof-of-concept to demonstrate how resilient tracking cookies can be.
Key Characteristics of Evercookie
- Self-regenerating: Deletes itself from one location? It restores from another.
- Difficult to remove: Uses multiple storage methods beyond standard cookies.
- Cross-browser tracking: Can persist across different browsers on the same device.
- Bypasses user privacy controls: Incognito/private browsing mode does not stop it.
This makes Evercookie an effective tool for advertisers, analytics firms, and even cyber attackers looking to track users across websites, devices, and sessions.
How Evercookie Works
Evercookie leverages multiple web storage technologies to ensure its persistence. When a user visits a website that deploys Evercookie, the tracking data is duplicated across multiple storage locations, including:
1. Standard HTTP Cookies
The most basic form of storage but easily deleted by users.
2. Flash Cookies (Local Shared Objects – LSOs)
Stored outside regular browser storage and not removed when clearing cookies.
3. HTML5 Storage
Uses LocalStorage and SessionStorage to store tracking identifiers.
4. IndexedDB & Web SQL Databases
Stores unique identifiers in browser databases that persist between sessions.
5. ETags & Cache Headers
Uses browser caching mechanisms to restore tracking data even after deletion.
6. WebRTC & HSTS Supercookies
Exploits browser security mechanisms for persistent tracking.
7. IP-Based & Device Fingerprinting
Combines Evercookie with fingerprinting techniques to identify users even when cookies are cleared.
Each time a user deletes a cookie, Evercookie reconstructs itself by pulling the data from one of the remaining storage locations. This makes it nearly impossible to erase completely without advanced privacy tools.
Why Evercookie is a Privacy Concern
Evercookie has raised serious privacy concerns because it enables continuous user tracking, even when users attempt to clear their data.
1. Bypasses User Consent
Even when users delete cookies, Evercookie reinstates itself, making privacy controls ineffective.
2. Cross-Session & Cross-Browser Tracking
Evercookie can track users across different browsers on the same device, making it more invasive than regular cookies.
3. Cannot Be Removed with Standard Methods
Clearing browsing history, cookies, and even using incognito mode does not fully erase Evercookie.
4. Regulatory Concerns
Many privacy laws, including GDPR (Europe) and CCPA (California), require user consent for tracking. Evercookie’s design makes it difficult for users to opt out, raising compliance issues.
How to Detect and Remove Evercookie
Since Evercookie spreads its tracking data across multiple storage locations, removing it requires a multi-layered approach.
1. Use Privacy-Focused Browsers
Some browsers, such as Brave and Firefox, have built-in tracking protection against Evercookie.
2. Clear Multiple Storage Locations
Manually delete:
- Standard Cookies (Browser settings > Clear Cookies).
- Flash Cookies (Adobe Flash settings manager).
- HTML5 Storage (Developer Console > Application Storage).
- IndexedDB & Web SQL (Developer Tools > Storage).
- Cache & ETags (Clear browser cache and force reload).
3. Block Tracking Scripts
uBlock Origin, Privacy Badger, and NoScript can help prevent Evercookie from being set.
4. Disable WebRTC and HSTS Supercookies
Adjust browser settings to block WebRTC leaks and prevent HSTS tracking.
5. Use Anti-Tracking Tools
VPNs, private browsing modes, and anti-detect browsers can reduce tracking risks.
6. Factory Reset (Last Resort)
In extreme cases, some tracking data may persist beyond browser settings, requiring a complete system reset.
Key Takeaway
Evercookie is one of the most persistent and invasive tracking technologies ever developed. Unlike traditional cookies, which can be easily deleted, Evercookie reconstructs itself using multiple storage techniques.
To protect against Evercookie tracking, users must take advanced measures, such as clearing all storage types, using privacy-focused browsers, and disabling WebRTC tracking. With the increasing focus on online privacy regulations, Evercookie’s existence raises serious ethical and legal questions regarding user tracking and consent.
People Also Ask
Evercookie recreates itself from multiple storage locations after deletion, while regular cookies disappear once cleared.
It bypasses standard user privacy controls, making it almost impossible to remove completely without advanced tools.
Yes, Evercookie can store data in Flash, HTML5, IndexedDB, and other methods, enabling cross-browser tracking.
No, Evercookie persists even in private browsing because it uses storage methods beyond standard cookies.
A combination of clearing all storage types, using anti-tracking extensions, and adjusting browser settings is required.
Using anti-tracking browsers, VPNs, and blocking JavaScript-based tracking scripts can help mitigate its effects.
Related Topics
Cookie Manager
A cookie manager is an essential tool that allows users to control and manage cookies on their devices. Learn more here!
Aged Cookies
Aged cookies refer to web browser cookies that have been stored on a user’s device for a prolonged period, often months or even years.
Flash Cookie Tracking
A peer-to-peer network is a distributed network structure in which peers communicate directly with each other to exchange information, resources, or services. Read more here.
Supercookies
Supercookies are tracking cookies that are stored outside the typical cookie storage locations and are harder to delete. Read more.
