In this blog post I explain how to set up the new AI agent runtime protection in Microsoft Defender for Endpoint. More and more of us run local AI agents on our work machines — coding assistants like Claude Code, GitHub Copilot CLI, and other CLI tools (I wrote before about why CLI tools are winning for AI agents). These agents are powerful, but they run with your user privileges. They can read files, run commands, and call tools. And they act on text from prompts, files, web pages, and tool output without really knowing which part is trustworthy.
That is exactly the problem. A hidden instruction inside a web page or a file can hijack the agent — this is called prompt injection. AI agent runtime protection in Defender for Endpoint inspects the agent at the right moments and can block these attacks before anything bad happens. The feature is in public preview right now, so use it on test devices only. Let me show you how it works and how to turn it on.
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