Mojave 10.14.5 on 2018 Mini. I had an odd thing yesterday. Mac had been on all day, but when I logged in last night around 20-25 disk images were sitting on the desktop. Mostly for applications I have, or have had, but generally older versions which I have not had on this Mini. Concerned, I just deleted them and they haven't reappeared. I have Intego & Little Snitch which don't show anything out of the ordinary, but could some nasty-ware have been installed?