By now I am sure we all realize that besides infecting your main hard drive(s), that Ransomware also will find and infect your backups. Most of us use USB drives or Network Shares for backups. But if you are backing up infected files what good are they?
Best practice is to physically disconnect your backup drive(s) while not in use. You can always just disconnect your USB drives.
My solution is the KF-255-BK from KingWin. It's a rack that installs in your computer - in which you can insert a 2.5", 3.5" Hard Drive or SSD. Best of all it's a hot swap device with an on/off switch. Insert a drive - run your back up then turn the drive off with one button and remove the drive. If your system is infected - your backups are safe. It's also easy to use old unused drives as redundant backups for your data - and easy to encrypt the drive (BitLocker or other) and toss in the trunk of my car for an off-site backup.