While families gathered for food and merriment on Christmas Eve, most businesses slumbered. Nothing was stirring, not even a mouse—or so they thought. For those at Tribune Publishing and Data Resolution, however, a silent attack was slowly spreading through their networks, encrypting data and halting operations. And this attack was from a fairly new ransomware family called Ryuk.

https://blog.malwarebytes.com/cybercrime/malware/2019/01/ryuk-ransomware-attacks-businesses-over-the-holidays/