Google and other advertising companies have been bypassing the privacy settings of millions of people using Apple's Web browser on their iPhones and computers—tracking the Web-browsing habits of people who intended for that kind of monitoring to be blocked.
The companies used special computer code that tricks Apple's Safari Web-browsing software into letting them monitor many users. Safari, the most widely used browser on mobile devices, is designed to block such tracking by default.
Google disabled its code after being contacted by The Wall Street Journal.
The Google code was spotted by Stanford researcher Jonathan Mayer and independently confirmed by a technical adviser to the Journal, Ashkan Soltani, who found that ads on 22 of the top 100 websites installed the Google tracking code on a test computer, and ads on 23 sites installed it on an iPhone browser.
The technique reaches far beyond those websites, however, because once the coding was activated, it could enable Google tracking across the vast majority of websites. Three other online-ad companies were found using similar techniques: Vibrant Media Inc., WPP PLC's Media Innovation Group LLC and Gannett Co.'s PointRoll Inc.
In Google's case, the findings appeared to contradict some of Google's own instructions to Safari users on how to avoid tracking. Until recently, one Google site told Safari users they could rely on Safari's privacy settings to prevent tracking by Google. Google removed that language from the site Tuesday night.
In a statement, Google said: "The Journal mischaracterizes what happened and why. We used known Safari functionality to provide features that signed-in Google users had enabled. It's important to stress that these advertising cookies do not collect personal information."
For more on Google's tracking policies, see the full story on The Wall Street Journal.