Users have taken to Apple's Support forums to complain about the attack, which presents as a message saying the device has been "hacked by Oleg Pliss". The hack appeared to compromise users' Apple ID and then take advantage of the Find My iPhone feature to remotely lock down devices.
The first person to post about the hack, forum user Veritylikestea, said their iPad suddenly "locked itself" while an additional iPhone presented a message to send US$100 to a PayPal account to return access.
A number of other users, largely from Australia, took to the forum complaining of the same issue, saying they had been hit on multiple Apple devices at once and were forced to change iCloud passwords. Many reported being awoken around 4:30 a.m. by devices playing sounds and displaying the message.
"iPad woke me at 4.30am with the message 'Your device has been hacked by Oleg Pliss' and sound -- I thought it was the morning alarm," wrote user deskokat. "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."
The problem has also reportedly popped up in New Zealand, while one Australian user also commented that they were in London when the error message appeared.
Australian telcos Optus and Vodafone say they have not received any official complaints about the issue. An Optus spokesperson said, "If customers have any questions about their Apple devices, they should speak directly to Apple"; similarly, Vodafone said it was encouraging those with concerns "to speak with Apple as they are best placed to offer comment on their services".
A Telstra spokesperson said, "We're aware of the reports and we've referred the matter to Apple. In the meantime customers who need assistance can contact Apple Care".
CNET has sought comment from Apple on the issue.
Updated, May 27 at 4:00 p.m. AEST to include Vodafone comment.
Updated, May 27 at 5:41 p.m. AEST to include Telstra comment.
Updated, May 28 at 12:21 p.m. AEST to include Find My iPhone details.