Researchers from the Georgia Institute of Technology managed to get a malicious app approved by Apple and included in the App Store by using a ‘Jekyll & Hyde’ approach, where the behaviour of a benign app was remotely changed after it had been approved and installed.

It appeared to be a harmless app that Apple reviewers accepted into the iOS app store. They were later able to update the app to carry out a variety of malicious actions without triggering any security alarms. The app, which the researchers titled “Jekyll,” worked by taking the binary code that had already been digitally signed by Apple and rearranging it in a way that gave it new and malicious behaviors … 

The researchers presented their findings in a paper at the USENIX Security Forum.

Our method allows attackers to reliably hide malicious behavior that would otherwise get their app rejected by the Apple review process. Once the app passes the review and is installed on an end user’s device, it can be instructed to carry out the intended attacks. The key idea is to make the apps remotely exploitable and subsequently introduce malicious control flows by rearranging signed code. Since the new control flows do not exist during the app review process, such apps, namely Jekyll apps, can stay undetected when reviewed and easily obtain Apple’s approval.

An Apple spokesman told MIT Review that changes have been made to iOS as a result of the exploit, but it’s not yet clear whether the change is to iOS 7 or the older iOS 5 and 6 versions attacked. The researchers only left their app in the store for a few minutes and said that it was not downloaded by anyone outside the project in that time.

Apple Senior Vice President Phil Schiller tweeted back in March about a study revealing the rising incidences of malware on Android. The study showed that Android accounted for 79 percent of all mobile malware in 2012, while iOS came in at less than 1 percent.

Via arsTechnica