The problem with the sites that automatically back up your files is that they will back up the new "changed" file (overwriting the original) which would be the locked one (if you had this virus). I use carbonite and they claim to keep old copies of files for 3 months but I take no chances. I use smugmug to back up my photos and have an external drive that I keep disconnected when I'm not using it for everything else that I don't want to lose. I just add any new files to the external every few days.