So, anyway, instead of calling people idiots, I'm just gonna actually try to help.
If you get a message saying "You will exchange this thing?" with a link at the end, DO NOT CLICK THE LINK.
If you did, then DON'T DOWNLOAD IT.
If you have Google Chrome like me and it downloaded automatically, DO NOT OPEN IT.
Your alarm bells should have gone off when you saw it was an .scr file instead of a .png like the link showed. Google the message you got next time you get a weird and senseless message from a friend.
If you did run it, use Malwarebytes and your Antivirus and whatever else you have to scan the computer and get rid of it.
I googled "you will exchange this thing virus" and read about it being a Russian rootkit or something. So that's kinda bad. Warn all your friends if you are sending out those links too!
What does "you will exchange this thing" mean anyway? That's not even a sentence.
And a life lesson:
Don't ridicule people just because you found something your smarter at for once. Not everybody is good with computers. I know you think people have to be really careless to fall for that, but some people don't even know how a virus/malware works. Especially with all the really young people that are playing on your server. At least change the title to something like "WARNING: STEAM VIRUS - REALLY IMPORTANT" or something even remotely helpful. (It's also a bit embarrassing if you have a glaring typo in a title while calling people idiots.)