Microsoft makes Windows 11 agent containment generally available with MXC
Microsoft Execution Containers are now generally available on Windows 11, limiting which files and networks AI agents can reach. Here is what shipped and what didn't.
On October 7, Microsoft made Microsoft Execution Containers (MXC) generally available on Windows 11. The idea: organizations define which files and networks agents can access, and those policies are enforced at runtime. Microsoft's developer blog says the policy stays outside the agent's control, so "the agent or generated code cannot grant itself additional access."
There are three modes: Enforcement blocks ungranted access, Learning blocks and logs it in JSON, and Permissive allows and logs it. Windows 11 alone supports session containers, which run an agent in a separate session with its own local agent identity and isolated desktop, clipboard, UI and input. Process containers also work on macOS and Linux. MicroVM is experimental on Windows 11 and Linux.
Microsoft lists Codex from OpenAI, GitHub Copilot, OpenClaw, Replit, LM Studio, NVIDIA's OpenShell and Unsloth AI as supporting MXC now. Anthropic's Claude Code, Perplexity and Manus are among those coming. Entra support for separating agent activity from user activity and Intune policies for MXC process containers are both listed as "soon," with no date.
The context is Satya Nadella's own framing. He told The New Things: "I think of all agents as insider risk and treat them as such."
My take: a boundary the agent cannot edit is the right design. But the announcement gives no independent test of whether the walls hold, and The Verge noted the security pitch sounded aimed at businesses, not ordinary Windows users. Learning mode is the honest part: block the ungranted access, then keep the receipts.
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Sources
- Building Windows for hybrid intelligence, Windows Experience Blog
- Microsoft Execution Containers: Policy-driven containment for AI agents, Windows Developer Blog
- Microsoft CEO on rogue AI agents, super laptops and Clippy, The New Things
Meanwhile at the anchor desk
Containment on Windows 11, with Codex, Copilot and soon Claude Code in the same room! Nothing says confidence like a company calling its own AI an insider risk.
MXC is GA on Windows 11 with a JSON schema and SDK. Start in Learning mode, read the log, then flip to Enforcement. Entra and Intune hooks are still "soon."
