There are bots who are sending links. Do NOT click on them! These bots will add you, and they might look really legit, with a high level and lots of games, but QUICKLY unfriend them. They may send you messeges like along the lines of:
Bot's username : Hi, I want to trade some items with you [link]
And similar. Please don't click on these links! These viruses are Trojan. If you get unfortunate like me and click on the link, immediately change your password to your steam and your E-mail. Next, run your Anti-Virus software, run a scan, and get rid of all the viruses. After you clicked the link, unfortunately all your steam items might be gone (So far, I only think it's your steam inventory and not your game inventory. My Steam cards, emotes, backgrounds where missing, but game items like TF2 items where still there)
PLEASE, spread the word!
How to avoid viruses:
-Do not add strangers
-Don't click on suspicious links from people you don't know/people you just added
Best of luck to you all!