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- Author of the post, and dev of mcp-box here. Wrote this after realizing every MCP server on my machine had the same access to ~/.ssh that I do, and nothing in the installation messages posting to stdout mentions it. I think prompt injection is the vector and the permissions model is the red carpet giving a warm welcome. Interested in where that's wrong.by lowcache
- I've created boxy [1] to sandbox the agents via Landlock and gh-proxy [2] to not share GH PATs that might leak over the internet.
I have a far better setup on my Kubernetes cluster [3], but these are good building block (IMHO) to start preventing these kind of issues.
I also "recklessly" run `claude` / `codex` as root for certain things - but that happens on a completely separate machine that is meant to be pruned afterwards, and it's what unlocks the kernel development feedback loop that is needed to port a device (such as the Daylight DC-1 / Surface Pro X) to mainline Linux.
[1]: https://github.com/denysvitali/boxy
[2]: https://github.com/denysvitali/gh-proxy
by denysvitali - A fairly comprehensive list of ways you should be sandboxing your agents: https://pleasedonotescape.com/
If you like a real focus on developer experience and want lots of bells and whistles that a lot of thought has gone in to, I wrote byre, which I think is very good: https://github.com/pjlsergeant/byre
by petesergeant - I once opened Zed, howdy there was an agent window on the side, I log into Claude. I asked it to list what it could see and work with... And there my (priv) ssh keys come scrolling by. I don't know what I was expecting really, it's very logical, but also very in your face. They didn't leave my computer I guess, I just showed me the output of some `ls` commands. But still.
So now I have CC in a container, mounting it's own credentials/memory folder per project and only mounting one repo at a time (script in the repo itself). I feel a bit better about it now. It can still access my networks of course.
by teekert - Expecting an agent harness to respect security boundaries is definitely the wrong thing.
We need to have easy to use auditable sandboxing of agents and their harnesses, because it's quite clear certain model providers are going to try to lock us in at the harness level, and it's those harnesses that seem most likely to go nuts.
by fidotron - So this looks like Claude is discussing the idea that when you run untrusted code on your computer, it can do arbitrary things. If there is malicious code, maybe it'll read your files and steal your credentials.
Here's a sample: "That’s not hypothetical. That’s POSIX working exactly as designed. None of it requires exploiting anything. It’s your user account doing normal user account things."
I would recommend clicking TFA if you haven't heard of a supply chain attack, or if you just like getting the honest load-bearing facts that are worth mentioning.
by tux3 - This is why I run opencode and similar things in a dedicated KVM virtual machine that lives on a system under my desk that doesn't have access to my user account data, documents folder, photos/video, ~/.ssh/, other API keys, ~/.anything-else/, you name it.
I think it's absolutely wild that there are people out there running cutting-edge LLMs and agent harnesses and tools on the same hardware and same user/disk/session environment that contains like, PDFs of their paystubs, their 401k records, their tax returns for previous years, contracts/real estate details, whatever other personal things you keep in your Documents folder as an educated modern professional with obligations and debts and assets.
Sometimes this VM gets duplicated for specific projects and then various dependencies for testing installed in it that are specific to what the needs are.
As an additional advantage it means I can leave it running in the background doing things when I want to shut my laptop, then resume talking to it later.
(edit, for everyone who hasn't seen it yet, take a look at the "grok uploads your entire code base" category of problem: https://www.google.com/search?client=firefox-b-d&q=grok+uplo... )
by walrus01 - This article smells AI generated, which is _very_ funny given the argument being made.
Either way, while this is true in the absolute, this is the value of building good MCP servers: they should expose only exactly the surface you expect your agent to need, and adding functionality should be carefully considered. The best MCP servers I use day to day (Cloudflare sticks out) do a really good job of exposing only what an agent might actually want to do on my behalf, rather than just all and sundry. Unfortunately the Chrome Dev tools MCP is less discriminating and is only as secure as a browser sandbox with full JS access (not fatal but not as strong as a well scoped REST API).
All of this is sidestepped somewhat by using good isolation primitives - I'm running a Hermes agent as of recently on a DigitalOcean VM that only accepts connections from my devices over tailscale, and it has all its own credentials so I can revoke them easily should they be used maliciously. Giving an agent root on a box is not _necessarily_ a huge deal, you just have to make sure that box has nothing valuable on it.
I kinda feel like we're rediscovering "Cattle, not Pets" when it comes to the environments we run our agents: give it root, sure, but a root that is almost meaningless outside of the functionality you granted it.
by nameless912