Users Reported on Apple's support forums that there is message on their IDevices which says that they have been hacked by Oleg Pliss and to send payments to a PayPal account so they can get the device unlocked.
"i was using my ipad a short while ago when suddenly it locked itself, and was askiwhich I'd never previously set up. I went to check my phone and there was a message on the screen (it's still there) saying that my device(s) had been hacked by 'Oleg Pliss' and he/she/they demanded $100 USD/EUR (sent by paypal to lock404(at)hotmail.com) to return them to me."
Users facing this problem have most likely been hacked due to a weak passwords or a phishing attack. To prevent your IDevice from being hijacked, it is strongly recommend that you enable two-factor Authentication on your Apple ID, update your older, probably weaker passwords on iCloud and be sure to use a passcode on your iOS device as those devices with a passcode can't be remotely locked.

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