The DXXD Ransomware has been targeting servers and encrypting their files since the end of September. It also modifies a Windows registry key so that it displays a ransom note before a user logs in to Windows. Researchers have been able to create a decryptor for this new variant of the ransomware. This decryptor was being distributed to victims privately in order to prevent the developer from learning the weaknesses in their encryption method. If you are encrypted by the DXDD ransomware, you can register an account and reply to the DxxD Help and Support topic to receive help.
Source: https://www.bleepingcomputer.com/news/security/the-dxxd-ransomware-displays-legal-notice-before-users-login/