Ransomware is a rather insidious form of malware that attempts to render all of your important files unreadable, until you pay the perpetrator a ransom to restore them. This malware was first seen in Russia in 2011, and by 2013, it was well entrenched in the U.S. This malware genus has grown in occurrence and sophistication in recent months. One of the best known forms, called CryptoWall, has just entered Version 4, with a greatly improved ability to hide from antivirus software.”]
Source: https://www.csoonline.com/article/3023543/ransomware-7-tips-for-recovery-and-prevention.html