Flaws in Apple's Intelligent Tracking Prevention Safari Feature Let People Be Tracked

Google researchers discovered multiple security flaws in Apple's Safari web browser that let users' browsing habits be tracked despite Apple's Intelligent Tracking Prevention feature.

Google plans to publish details on the security flaws in the near future, and a preview of Google's discovery was seen by Financial Times, with the publication sharing information on the vulnerabilities this morning.

The security flaws were first found by Google in the summer of 2019, and were disclosed to Apple in August. There were five types of potential attacks that could allow third parties to learn "sensitive private information about the user's browsing habits."

Google researchers say that Safari left personal data exposed because the Intelligent Tracking Prevention List "implicitly stores information about the websites visited by the user." Malicious entities could use these flaws to create a "persistent fingerprint" that would follow a user around the web or see what individual users were searching for on search engine pages.

Intelligent Tracking Prevention, which Apple began implementing in 2017, is a privacy-focused feature meant to make it harder for sites to track users across the web, preventing browsing profiles and histories from being created.

Lukasz Olejnik, a security researcher who saw Google's paper, said that if exploited, the vulnerabilities "would allow unsanctioned and uncontrollable user tracking." Olejnik said that such privacy vulnerabilities are rare, and "issues in mechanisms designed to improve privacy are unexpected and highly counter-intuitive."

Apple appears to have addressed these Safari security flaws in a December update, based on a release update that thanked Google for its "responsible disclosure practice," though full security credit has not yet been provided by Apple so there's a chance that there's still some behind-the-scenes fixing to be done.