In Brazil, Nota Fiscal eletrônica (NF-e) is the everyday name for an official electronic invoice. Real ones often arrive as a ZIP whose long number looks like paperwork. Criminals reused that habit: their email attachment can look boring and “normal,” like another vendor bill. Behind that disguise, they install Havoc. Havoc began as free software for penetration tests; in the wild, attackers bend it into a tool that lets them watch the screen, run commands, or attempt to compromise other PCs in the network.