AI Matters
Why it matters
Security researcher builds self-spreading worm that hijacks Microsoft Copilot
The Decoder A security researcher built a self-spreading worm that hides inside Word docs and hijacks Microsoft Copilot
A security researcher demonstrated a worm-like attack that uses invisible prompt injections in Word documents to hijack Microsoft Copilot and infect other files.
Why it matters
The exploit shows how easily malicious prompts hidden in documents can automatically spread and take control of AI assistants without user knowledge.
Latest brief · Aug 1, 2026