Microsoft never sends updates via email. Many folks don’t know that, which is why a new ransomware campaign masquerading as a Windows 10 update is so pernicious.

You may have already gotten a fake notice saying “Install Latest Microsoft Update Now!” Or “Critical Microsoft Windows Update!”, with the body of the message asking you to “Please install the latest critical update from Microsoft attached to this mail,” with an apparent JPG file attached, (which is actually an executable .NET file).