Hidden prompt turns Microsoft Copilot into an AI worm

A security researcher has demonstrated how Microsoft Copilot for Word can be tricked into spreading a self‑propagating prompt‑injection “AI worm.” The attack silently alters documents and embeds its own hidden instructions into newly created files, allowing it to spread through normal document-sharing workflows without macros or traditional malware. The technique allows an attacker to hide a JSON‑formatted prompt as white text on a white background inside a Word document.