Malware
Xorist
According to PCrisk, Xorist is a family of ransomware-type malware.
Xorist is a Windows malware family.
Background
PCrisk describes Xorist as a family of ransomware-type malware. Once it has quietly infiltrated a system, it encrypts a variety of files held on the computer. Following encryption, it drops a 'How to Decrypt Files.txt' text file onto the victim's desktop, with a message explaining that the files can only be recovered by paying a ransom.
Source: Malpedia (Fraunhofer FKIE).