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As the title says, I'm wondering if there are any security/privacy benefits to managing cookies - that is, managing by deleting cookies you don't want or need.

I deleted all my cookies about a week ago and since then I've left a tab open in Chrome with the list of cookies. (chrome://settings/cookies) A few times a day (when I think of it), I refresh the list and go through it and delete any cookies I don't really need. In my case, other than a bunch of StackExchange sites and a couple of others that I like to stay logged in to, I've been deleting almost every site's cookies.

This doesn't take very much time and it's been interesting to see which sites lead to cookies from various advertising sites, but is it doing me any good in terms of maintaining a bit more privacy on the Internet?

AviD
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Ward - Reinstate Monica
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3 Answers3

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I would say yes and no at the same time.

Advertising company are using some clever techniques (including cookies) to identify your browser :

  • Your classic cookies (which are now gone).
  • Flash cookies : you can store content in flash which can be using for cookies (very common now).
  • Your browser fingerprint (HTTP Header fingerprint, fonts installed, OS, browser version, Time location) with your ip address can be used to retreive information from deleted cookies.
  • You can store things directly with HTTP headers (HTTP cache) but I don't know a lot about it.
  • Css visited links (via faux links with data).
  • Browser cache can also be used for storing cookies

I suggest looking at the evercookie project, its quite interesting.

Rory Alsop
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redpile
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Excellent answer by @redpile. The fact that the tracking techniques evolve doesn't mean you cannot protect yourself against them (at least to some extent).

There are still some protection mechanisms you can use to selectively block certain traces from your browser and protect your privacy. Take a look at the answer to this question for some examples. I also just found this firefox plugin for managing flash-based cookies.

That said, you might also lose-out from erasing some cookies. For example, you would need to authenticate again and again to some sites you visit if your browser doesn't 'remember' you. The results you might get won't be tailored to your specific profile (which might be a good or a bad thing) etc.

Selectively blocking ads and banners or certain sites you don't want to share your info with is usually an easy-enough compromise and gives you less 'noise' on the browser. This wouldn't completely preserve your anonymity but will reduce the amount of data you are making available to advertisers. Tuning these privacy settings and browser plugins can become a nuisance in itself however. It all depends on how privacy-aware / paranoid you feel.

Community
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Yoav Aner
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Rather than managing cookies by trying to delete them in ad-hoc ways, I suggest that you use various tools to protect your privacy. Those tools generally work by blocking the cookies in the first place. For instance, you could look at Privoxy, TACO with Abine, AdBlock Plus, NoScript, and GoogleSharing. I've found these to be pretty effective.

D.W.
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