http://spywareitdaiuyfo2sqb5vsg7mek5cjabdr73luhnda57t2hyuzg7yyd.onion/articles/itunes.html
The only hint we have comes from this passage in the privacy policy [1] : "We may collect information such as occupation, language, zip code, area code, unique device identifier, referrer URL, location, and the time zone where an Apple product is used so that we can better understand customer behavior and improve our products, services, and advertising."