Apparently, this is easy to do. Charlie Osborne:
US researchers have discovered a flaw which may exist across Android, Windows, and iOS operating systems, and could allow popular services such as Gmail to become compromised… The attack works through a user downloading a seemingly harmless application, such as background wallpaper. Once installed, the researchers were able to exploit a newly discovered public side channel, the shared memory of a process, which can be accessed without permissions or app privileges.
Is nothing secure?