It has been discovered that even if you were to put a passcode lock on your iPhone, by enabling Siri, you will be able to enable Airplane Mode which would ultimately disable Find My iPhone. This isn’t so much a bug but more of an oversight especially since Siri has now been given more functionality with the update. We expect Apple will want to swiftly address this issue if they hope that the new iOS 7 update will be a secure one. In any case there’s still the Activation Lock feature that thieves need to go through if they wish to completely wipe the device and resell it, but for now they are still able to disable Find My iPhone which would make it harder for them to be tracked down.