Letting off steam

This Group-IB report analyzes a sophisticated phishing campaign impersonating Steam that uses the browser-in-the-browser technique to display convincing fake authentication pop-ups (including fake address bars and SSL lock icons) to harvest account credentials and 2FA/SMS codes; the analysis covers the phishing kit files and logic, C2 responses, attacker recruitment on Telegram/underground forums, indicators of the kit behavior, and user/organizational mitigations to detect and prevent these attacks.