Stop opening PDFs attached to emails unless you’re absolutely certain about where they originated and who is sending them to you.

Not that most of you were likely opening such email attachments with wild abandon before now, but be warned — Microsoft’s Security Intelligence team has uncovered what sounds like a Trojan malware attack as part of a “massive” email campaign with a nasty payload — malicious PDFs, which download a password- and credential-stealing Java-based remote access Trojan called StrRAT. In addition to stealing credentials and even taking control of systems, Microsoft researchers have also found that this malware can disguise itself as faked ransomware.