From arstechnica.com
In September 2015, Apple managers had a dilemma on their hands: should, or should they not, notify 128 million iPhone users of what remains the worst mass iOS compromise on record? Ultimately, all evidence shows, they chose to keep quiet.
The mass hack first came to light when researchers uncovered 40 malicious App Store apps, a number that mushroomed to 4,000 as more researchers poked around. The apps contained code that made iPhones and iPads part of a botnet that stole potentially sensitive user information.