Microsoft Copilot: Self-Propagating XPIA Worm via Hidden Prompt Injection
Microsoft Copilot for Word is susceptible to a self-propagating Cross-Prompt Injection Attack (XPIA) stemming from a fundamental architectural inability to distinguish between untrusted user data and authoritative developer instructions. Attackers embed JSON-formatted payloads using white-on-white text obfuscation in .docx files. Upon ingestion, the AI agent elevates these hidden strings to high-priority system commands, enabling the worm to autonomously append itself to any subsequently generated or edited documents. This mechanism bypasses traditional EDR and AV signatures by utilizing authorized AI agents within enterprise workflows—specifically SharePoint and Teams—potentially leading to organizational-wide context collapse and unauthorized data exfiltration.