Researchers created concept ransomware that takes advantage of a feature in Windows that encrypts files and folders to protect them from unauthorized physical access to the computer. The lab-developed ransomware strain relies on the Encrypting File System (EFS) component in Microsoft’s operating system and can run undetected by some antivirus software. The researchers presented their findings to 17 other anti-malware and anti-ransomware vendors for Windows. Microsoft’s response, sent on October 7, 2019, was thee following: “Microsoft considers this submittal to be a moderate class defense in a future product”””
Source: https://www.bleepingcomputer.com/news/security/windows-efs-feature-may-help-ransomware-attackers/