Data Encrypted for Impact
An adversary may encrypt files stored on the mobile device to prevent the user from accessing them, for example with the intent of only unlocking access to the files after a ransom is paid. Without escalated privileges, the adversary is generally limited to only encrypting files in external/shared storage locations. This technique has been demonstrated on Android. We are unaware of any demonstrated use on iOS.
A static analysis approach may be able to identify ransomware apps that encrypt user files on the device.