Soviet Fireball here.
Somebody had hijacked my account and began to attempt scamming my friends. I never actually did this; someone posing as a Valve employee (who was also using a friend's account they had hijacked as well) asked me for my "duped items," saying they were "illegal." I complied, and I must have clicked on some link or something, because even though I didn't give them my password, they got into my account and I had to file a Steam support ticket.
PROOF:
Trade History with the User in Question:
https://i.imgur.com/SKUgYJF.png
Steam Support Ticket (w/ Response):
https://i.imgur.com/iHv9nsQ.png
Email Informing Me My Account Was Compromised:
https://i.imgur.com/8vwl5M1.png
My Profile As Viewed By Me Logged In:
https://i.imgur.com/rYaPANt.png
Profile Of Friend That Was Hijacked:
https://steamcommunity.com/id/897987987986546/
CHAT LOG WITH SCAMMER AS THE INCIDENT UNFOLDED:
https://imgur.com/gallery/uYpj9MP
NOTE: After the last image in the chat log album, I was automatically signed out of my account and no longer able to access it (until I filed a ticket to Steam Support and they reset the account password and email address).
If any further proof is required, I will add it in future posts to this thread.
Thank you,
(the real) Soviet Fireball