- We analyzed the results from over a quarter of a million people who ran our tests in the last few months, and found that we can detect browsing histories for over 76% of them. All major browsers allow their users' history to be detected, but it seems that users of the more modern browsers such as Safari and Chrome are more affected; we detected visited sites for 82% of Safari users and 94% of Chrome users.
- While our tests were quite limited, for our test of 5000 most popular websites, we detected an average of 63 visited locations (13 sites and 50 subpages on those sites); the medians were 8 and 17 respectively.
- Almost 10% of our visitors had over 30 visited sites and 120 subpages detected -- heavy Internet users who don't protect themselves are more affected than others.
- The ability to detect visitors' browsing history requires just a few lines of code. Armed with a list of websites to check for, a malicious webmaster can scan over 25 thousand links per second (1.5 million links per minute) in almost every recent browser.
- Most websites and pages you view in your browser can be detected as long as they are kept in your history. Almost every address that was in your browser's address bar can be detected (this includes most pages, including those retrieved using https and some forms with potentialy private information such as your zipcode or search query). Pages won't be detected when they expire from your history (usually after a month or two), or if you manually clear it.
For now, the only way to fix the issue is to constantly clear browsing history or use private browsing modes. The first browser to prevent this trick in a default installation (Firefox 4.0) is supposed to come out in October.
Here's a link to the paper.