My iCloud account was hacked by source supposedly from Kalunga Russia. My MacBook Pro and iMac desktop both show a lockout screen on start up and ask for a four digit PIN on my MacBook and a six digit PIN on my iMac Desktop. It says to email apple.device@gmx.com
There are reported fixes on REDDIT stating that resetting the PRAM / NVRAM by rebooting three times with the OPTION COMMAND P R keyboard combination will unlock the computer. I tried this and it does to work.
macosx - MacOS Ransomware with EFI Lock - Information Security Stack Exchange
Obviously someone has figured out how to hack into iCloud accounts bypassing two factor identification. This is a serious problem and Apple seems to be ignoring it as there is no information form Apple as to how to fix the problem or prevent icon accounts from being hacked. I assume Apple does not want to admit to security weaknesses.
If anyone has any information about this please post.