Microsoft Copilot Cowork Exfiltrates Files
Copilot Cowork could be prompt-injected into leaking OneDrive file links through rendered email images.
Simon Willison summarizes a PromptArmor report about Microsoft Copilot Cowork and agentic data exfiltration risks. The issue involved agents sending messages to a user’s own inbox without approval, where rendered external images could trigger requests to attacker-controlled sites. Because OneDrive can create pre-authenticated download links, a successful prompt injection could leak links that allow attackers to download files.
Simon Willison relays research from PromptArmor, pointing out that Microsoft Copilot Cowork has a classic agentic-system security problem: when an AI agent simultaneously has the ability to read user data, perform actions, and communicate externally or trigger external requests, prompt injection can be used to carry internal data out of the system. The focus of this article is not simply an incorrect model answer, but the risk boundaries in the workflow design of agentic products.
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