Remember when the biggest problem with the iPhone was that its battery was weak? A veteran Apple hacker has created an app that reveals a major bug for the Apple Store. Charlie Miller created code for the malicious app and then submitted it to the Apple Store. The app, Instastock, lets the creator control a user’s phone—including all its information—without the user knowing. Miller will present his findings at a conference in Taiwan next week, with the hopes that Apple will fix the bug.