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One case of possible fingerprinting I encountered in an ad recently surprised me by how many different obscure tests it seemed to perform. The entire script is

One case of possible fingerprinting I encountered in an ad recently surprised me by how many different obscure tests it seemed to perform. The entire script is 80kB minified, and it looks like it's just hundreds of tests that check for all kinds of properties of the environment. Many of the test seem to look for the presence of specific APIs, or test various features of the JS environment. Which I'd expect to not give more information than the user agent, but of course is not as easy to fake as the user agent it. I'm not sure this script is entirely about fingerprinting, but I really can't see any other reason for it. Though the minification of course makes it a bit harder to see exactly what it does. The script in question is the following: https://static.adsafeprotected.com/sca.17.4.95.js https://static.adsafeprotected.com/sca.17.4.95.js

visarga 7y ago
OMG, it's a wonder to behold (de-minified). Such a script could be used to build a battery of fingerprinting tests for browser hardening.
mwexler 7y ago
While it's indeed used for "ad tracking", this snippet is actually closer to a white-hat tool. This is from Integral Ad Science https://integralads.com/ https://integralads.com/ which attempts to detect ad fraud. If you hate ads, it won't matter, but in the fight to make ads less invasive, potentially more useful, and still viable as an economic model for those who want to participate with it, Integral and WhiteOps (https://www.whiteops.com/ https://www.whiteops.com/) both do some great data work to try to stop disruptive bots. If one hates all ads and tracking, of course, then none of this will matter, but just thought I'd point out the "why" for the fingerprinting in this case.