Compressed files are a convenient way to send multiple documents in a single attachment. But they're also an attacker's favorite hiding spot for evading security filters and delivering malicious executables straight to your inbox.
"Enable Content" is the most dangerous button in Microsoft Office. Behind that innocent prompt can hide a malicious macro that runs with your user permissions and can fully compromise your computer.
Receiving a file called invoice.pdf.exe should set off every alarm. The double extension technique is one of the oldest and most effective tricks attackers use to disguise executable files as harmless documents.