The following paper by Princeton University and Stanford University researchers was presented on May 20th at the 24th International World Wide Web Conference in Florence, Italy.
We study the ability of a passive eavesdropper to leverage “third-party” HTTP tracking cookies for mass surveillance.If two web pages embed the same tracker which tags the browser with a unique cookie, then the adversary can link visits to those pages from the same user (i.e., browser instance) even if the user’s IP address varies. Further, many popular websites leak a logged-in user’s identity to an eavesdropper in unencrypted traffic.To evaluate the effectiveness of our attack, we introduce a methodology that combines web measurement and network measurement. Using OpenWPM, our web privacy measurement platform, we simulate users browsing the web and find that the adversary can reconstruct 62-73% of a typical user’s browsing history.
We then analyze the effect of the physical location of the wiretap as well as legal restrictions such as the NSA’s “one-end foreign” rule. Using measurement units in various locations—Asia, Europe, and the United States—we show that foreign users are highly vulnerable to the NSA’s dragnet surveillance due to the concentration of third-party trackers in the U.S.Finally, we find that some browser-based privacy tools mitigate the attack while others are largely ineffective.