There is a new kind of Cookie in town. One that is almost impossible to delete. It stores itself in multiple places and if found, can be rebuilt and stored in all the places again.
Evercookie is an open source javascript API available, that produces extremely persistent cookies in a browser. Its goal is to identify a client even after they’ve removed standard cookies, Flash cookies (Local Shared Objects or LSOs), and others.
Evercookie accomplishes this by storing the cookie data in several types of storage mechanisms that are available on the local browser. Additionally, if evercookie has found the user has removed any of the types of cookies in question, it recreates them using each mechanism available.
Specifically, when creating a new cookie, it uses the following storage mechanisms when available:
- Standard HTTP Cookies
- Local Shared Objects (Flash Cookies)
- Silverlight Isolated Storage
- Storing cookies in RGB values of auto-generated, force-cached PNGs using HTML5 Canvas tag to read pixels (cookies) back out
- Storing cookies in Web History
- Storing cookies in HTTP ETags
- Storing cookies in Web cache
- window.name caching
- Internet Explorer userData storage
- HTML5 Session Storage
- HTML5 Local Storage
- HTML5 Global Storage
- HTML5 Database Storage via SQLite
BleachBit 0.8.7 is a cleaner which claims to deletes evercookies. It supports Internet Explorer, Firefox, Chrome, Opera, Safari and also works and Windows & Linux platforms.
Firefox users can also try Anonymizer Nevercookie, a free Firefox plugin that protects against the Evercookie API.
If you have liked this post, you might want to check out some more, on topics like Cookies.
