Categories: Google, Information Leakage, Search

Show me your Cookie and I’ll tell you what you visited

Web Search History Information Leakage

Back in February, I re-discovered a small flaw in Google Search: result personalization leaks the list of results you clicked on. This leak was already known and mentioned in a paper by Castelluccia et al., but several features added by Google made it critical.

The third point has been addressed by Google very recently, when they introduced the new interface with the black top bar.
Vincent Verdot and I wrote a paper about this flaw. In order to conduct an experiment, we’ve been working on a proof of concept and an evaluation tool that we used to gather results.

Proof of concept based on Firesheep

This proof of concept is based on Firesheep (I just added a module and modify the attack launched when a SID cookie was captured). Firesheep is only working with the latest version of Firefox 3.6, do not expect to run it on Firefox 5.
With our version of Firesheep, when a Google SID cookie is captured, the account name appears in the Firesheep sidebar. Double clicking on it starts the attack; double clicking again displays the retrieved list of visited links.

The Evaluation tool

We also designed a Firefox extension which downloads your web search history on your computer, issue a couple of search queries (mostly searching for extensions like: « .com, .fr, .us, .html, www, … ») and see how many clicked links can be retrieved.
We’ve run this experiment with a dozen of account and sent the result to Google. We’ll soon publish the paper as a technical report.

How to protect your Click History

We’ve been in contact with Google Security Team who is working on a fix that should soon be deployed. In the meantime, make sure you’re not logged in your Google account when you’re connected on an unsecured network.
If you do not use Web Search History you may also purge it and disable the feature (visit https://www.google.com/history).
Also, TrackMeNot and Unsearch will reduce the exposition of your click history.

 

Running the Test

If you want to run the test 5 minutes:

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