Tons Of Sites, Including WhiteHouse.gov, In Unwitting AddThis Experiment With Tracking Technology That Is Difficult To Block

from the our-post-cookie-era dept

ProPublica has a new story about the rise of "canvas fingerprinting," a new method of tracking users without using cookies. It's a method that is apparently quite difficult to block if you're using anything other than Tor Browser. In short, canvas fingerprinting works by sending some instructions to your browser to draw a hidden image -- but does so in a manner making use of some of the unique features of your computer, such that each resulting image is likely to be unique (or nearly unique). The key issue here is that the popular "social sharing" company AddThis, which many sites (note: not ours) use to add "social" buttons to their website, had been experimenting with canvas fingerprinting to identify users even if they don't use cookies. As ProPublica's Julia Angwin notes, it's very difficult to block this kind of thing -- and tons of sites make use of AddThis -- including WhiteHouse.gov (whose privacy policy does not seem to reveal this, saying it only uses Google Analytics as a third party provider).

The report does note that others who have tried canvas fingerprinting have found that it's not necessarily accurate enough yet, but the technology appears to keep getting better. Still, AddThis says it's likely to drop it anyway, because it's not good enough yet:

AddThis said it rolled out the feature to a small portion of the 13 million websites on which its technology appears, but is considering ending its test soon. “It’s not uniquely identifying enough,” Harris said.

AddThis did not notify the websites on which the code was placed because “we conduct R&D projects in live environments to get the best results from testing,” according to a spokeswoman.

The company also insisted it wasn't doing anything bad with the tracking, but even if you believe that's true, how long will it be until others make use of similar fingerprinting for more questionable behavior.

Given the attention this is getting, hopefully browsers will at least role out features that allow users more notification and control over such practices. Cookies are hardly a perfect solution, but at least users have control over them.

Filed Under: canvas fingerprinting, cookies, tracking, whitehouse, whitehouse.gov
Companies: addthis