A new ransomware called Satana was discovered by Malwarebyte security researcher S!Ri. When installed, the Satana Ransomware will encrypt your files using a standard file crypter and then also install a bootlocker to prevent you from logging into Windows. When encrypting the files, it will append an email address and then three underscores to the file name. The inserted email address is the one that a victim must contact after making payment in order to retrieve the decryption key. At this time there is no way to decrypt the encrypted files for free.
Source: https://www.bleepingcomputer.com/news/security/satana-bootkit-encrypts-your-files-and-then-locks-you-out-of-windows/