Zombie Cookie

Zombie Cookie

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A zombie cookie, also known as an evercookie, is a persistent tracking mechanism used by websites to uniquely identify and track users even after they have deleted regular browser cookies or taken steps to protect their privacy. It is designed to be highly resilient and difficult to remove.

Here’s how zombie cookies work:

  1. Storage Techniques: Zombie cookies use various storage techniques to store user identification data. These techniques include Flash cookies, HTML5 local storage, Web Storage API, IndexedDB, Silverlight Isolated Storage, and others. By utilizing multiple storage mechanisms, zombie cookies can persistently track users across different platforms and browsers.
  2. Regeneration: When a user deletes regular cookies, the zombie cookie recreates them using the stored identification data. This ensures that the user is tracked even if they take steps to remove traditional cookies.
  3. Replication: Zombie cookies often replicate themselves across different storage locations to make removal more difficult. If one storage location is cleared, the cookie can be retrieved from another storage location and recreated.
  4. Resilience: Zombie cookies are designed to be resilient to deletion attempts. They can use various techniques to restore themselves, such as detecting when they have been deleted and recreating themselves, or using backup copies stored in multiple locations.

The use of zombie cookies has raised concerns about user privacy and tracking practices. While some argue that they are used for legitimate purposes like maintaining user preferences or session information, others view them as intrusive and a violation of user privacy.

It’s worth noting that the use of zombie cookies may be subject to legal and regulatory requirements, such as obtaining user consent for tracking activities. Users concerned about zombie cookies can take steps to protect their privacy, such as regularly clearing their browsing data, using privacy-focused browser extensions, or disabling third-party storage mechanisms.

Overall, zombie cookies are a persistent tracking mechanism that allows websites to identify and track users across browsing sessions. They are considered controversial due to their ability to bypass regular cookie deletion and their potential impact on user privacy.

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