The address book in smartphones — where some of the user’s most personal data is carried — is free for app developers to take at will, often without the phone owner’s knowledge.
Companies that make many of the most popular smartphone apps for Apple and Android devices — Twitter, Foursquare and Instagram among them — routinely gather the information in personal address books on the phone and in some cases store it on their own computers. The practice came under scrutiny Wednesday by members of Congress who saw news reports that taking such data was an “industry best practice.”