Paranoid newb question about cookies & privacy

Ok, perhaps this is just lunatic paranoia.

I have an odd habit. When I visit a website that uses session cookies, I tend to delete all cookies before I visit any other website. My fear is that other websites, or their third-party advertisers, could read the cookies left by OTHER websites and thereby obtain logins/passwords (or hashes that could somehow be used to yield them), or personally identifiable information.

Is this crazy? If so, is my cookie-deleting "habit" worthwhile for any other reason? I suppose it would just be a lot more convenient to let Firefox delete all the cookies automatically when I shut the program down.

 

Quote taken from the READ & RUN ME FIRST Malware Removal Guide as administered by chaslang, MGs resident MVP on Security.

12) The True Story About Cookies!

First let's get right to the point. Cookies are not problems that you need to be concerned with. Too many antispyware programs flag cookies and make them sound like they are high risk items. The truth is that they are not high risk problems and in most cases are actually very useful to you.

This subject has long been debated on the internet and obviously there are many opinions about cookies. Cookies are not executable programs. They are simple text files stored on your PC to help websites (and you) track useful user settings and non-personal information, like which advertisement you last saw (which prevents you from seeing the same ad over and over again).

Yes some cookies are often referred to tracking cookies, but tracking is more complicated then just having a cookie. Every website you visit would have to have knowledge of the particular cookie so that they could use it to add tracking info to it and to make use of it. You will see many antispyware programs indicating various cookies as tracking cookies and this can artifically make detection counts look very high. It is also a sore point when doing comparisons between antispyware programs. If one program detects cookies and another does not, it can make the one that does not detect them look like it is doing a bad job.

Similarly it makes the one detecting them look like a great product since it picks up things the other missed. Thus most (not all) programs will detect cookies to avoid this hazard. Don't be fooled by cookie counting. If cookies are the only thing showing up, you are in good shape. They are not harmful and you can just ignore them or if so desired, you can easily clean them using your browser or other tools like CCleaner.

 

These look like the bad guys to me!!

http://www.wired.com/epicenter/2009/08/you-deleted-your-cookies-think-again/

 

I'd be more concerned about Flash cookies, Google, MSFT OS's and the FX add-ons.

Use a Live CD, let them try to store data on that.

 

You omitted DOM Storage. Surfing the web nowadays is anything but anonymous even if you go to extremes and use Tor or such.

Good Luck