Today was certainly an unpleasant day for some Australians who woke up to a rather shocking revelation that their devices had been hacked. According to The Sydney Morning Herald, a hacker who has apparently been using the name "Oleg Pliss" has been using some tactics to systematically freeze iPhone, iPad and Macs. This leaves the users locked outside their own devices with no options for any access. These users were blackmailed or were held as hostages for ransom because they could get access once they made payments between of between $50 and $100. So as it appears, the hacker has found an extremely fast and clever method to make money.
If you want to know more about the entire process about how the hacker used Apple's own Find My iPhone feature to remotely lock devices and send messages requiring payment via PayPal then you should check out the threads on Apple's official support forums.
The users who had set passcodes to their devices were the lucky ones as they managed to get access to their devices because you can't add or change a lock on a device that already has one in place. The ones who had absolutely no form of any security measure had a lot to lose unfortunately.