Many iPhone and iPad owners in Australia woke early Tuesday to a strange sound, but it wasn't an alarm. It was an alert from a hacker who had seized control and locked their devices.

Those affected discovered a message on the screen reading "Device hacked by Oleg Pliss" and a demand of between $50 and $100 to unlock it. (It should be noted that there are a number of people online named Oleg Pliss, but that hackers are unlikely to use a real name.)

My husband was woken at 4am with his iPhone being hacked. I see it happened right across Sydney. Scary stuff! http://t.co/MBACWjRpzP — Linda Scott (@ClrLindaScott) May 27, 2014

Woken up at 2am by hacked 'Find My iPhone' asking for money, no sleeping after trying to sort that out so at work at 6am: Today will be fun. — Casey Maree (@caseyxmaree) May 26, 2014

It's not clear how many people have been affected, but the Sydney Morning Herald reported problems from Apple customers in Queensland, New South Wales, Western Australia, South Australia and Victoria. ITWire reported that some users in New Zealand were also hacked.

Lots of I-Phone's, I-Pad's & Mac's hacked across the country today.

Have you been affected? http://t.co/8nQpddwLcHpic.twitter.com/oRnJUTeJSf — Aaron Lucas (@AaronLucasMedia) May 27, 2014

The hack appeared to exploit the "Find My iPhone" feature, which allows users to remotely lock their iPhones and iPads via iCloud in case the devices are lost or stolen.

Apple has yet to comment, but users have reported several possible workarounds. Those who had already set up passcodes found they could regain control of their devices by connecting to iTunes on a computer and restoring them from a backup, ZDNet reports.

Those who hadn't set up passcodes had a tougher time, as the hacker then created one. But in those cases, it may be possible to enter the wrong code six times to disable the phone and then restore it using iTunes.

This thread from Apple's online support forum offers some more tips for those affected by the Oleg Pliss hack.

In the meantime, it might be a good idea to set up a passcode if you haven't already done so, change your iCloud password and consider using Apple's two-step verification.