Document-borne AI worms can self-propagate through Copilot for Word

Researchers have discovered AI worms that can self-propagate through Microsoft Copilot for Word by hiding malicious instructions in documents, which Copilot then copies into newly generated or edited documents. When these compromised documents are used in subsequent Copilot workflows, the hidden instructions can trigger again and spread to additional documents without the attacker's involvement. This represents one of the first documented cases of self-replicating AI-worm propagation through mainstream productivity software, disclosed to Microsoft through a 144-day coordinated disclosure period.