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Supercookies

Explore the concept of supercookies, which are cookies set on top-level domains and blocked by browsers due to privacy and security concerns. Understand how supercookies differ from traditional cookies and other tracking methods like ETag tracking, examine real-world examples of unwanted user tracking by ISPs, and prepare to learn crucial cookie security flags that protect user information.

Introduction

What if we were able to set a cookie on a top-level domain (TLD) such as .com or .org? That would be a huge security concern, for two reasons:

  • user privacy: every website running on that specific TLD would be able to track information about the user in shared storage
  • information leakage: a server could mistakenly store a sensitive piece of data in a cookie available to other sites

In the following code, by appending ?super=on to the URL, the server is going to set a cookie on the domain local (e.g., wasec.local). Since it is a ...