iPhone 5C
File photo of an employee showing off an Apple iPhone 5C at a Verizon store in Orem, UtahReuters

Apple users mostly from Australia have complained of their devices like iPhone, iPad and Mac being attacked by hackers. The users claimed that their devices "locked itself" and a message demanding a certain amount appears on the screen in order to get back the access.

Several users took to Apple's Support Communities on Monday, complaining of receiving a message claiming that their devices have been hacked.

Veritylikestea, a user of the Apple's Support forum from Australia, complained of receiving a message that the device had been hacked by 'Oleg Pliss' and demanded to pay $100 USD/EUR by PayPal to get back access.

"I have the exact same problem, with the same message from "Oleg Pliss". I assume I can erase my phone, but is there anything else that can be done? I have changed my iCloud password," wrote ShellsBells57 in response to one of the posts complaining of the glitch.

"I have the same problem, with the exact same message. Affecting both my iPhone and iPad. Have reset passwords on all my applications (banking, email, social media etc) just in case," wrote another user by name slcurtis. "I'm assuming there is going to be a lot of people affected by this hacking. I wonder if this is associated with the recent icloud hacking in the media."

Many users said that the sound made by "Your device has been hacked by Oleg Plis" message woke them up.

"iPad woke me at 4.30 am with the message 'Your device has been hacked by Oleg Plis' and sound - I thought it was the morning alarm," wrote user deskokat on the forum. "I just signed in with my code, and all seems ok. I then signed in to my powerbook - but as a guest user - VERY grateful I did. Message to say I'd been hacked there too, wouldn't let me sign out without erasing all data for that user. As there was nothing but a couple of expendable files on there, I signed out. And the guest user portal has been erased." 

One of the users suggested to change iCloud password, as hackers can lock a device with a passcode and send messages, adding that one should sign out of the Apple ID before unlocking the device.

Another user, poppyp_z claimed that Optus, telecommunications company in Australia, suggested to keep the "phone off mode for now" on calling the company for help.

Spokespersons of Optus and Vodafone reportedly told CNet that they have not received any official complaint from users of Apple devices but suggested the customers to speak to the Cupertino giant directly if they face any problem. 

It may be recalled that Dutch hackers, who called themselves by the names AquaXetine and Merruktechnolog, recently claimed that they could unlock stolen iPhones by cracking Apple's security. It came as a surprise, as the Cupertino giant's online storage service iCloud has never come under threat from hackers in the past.