How secure is Node's vm for running untrusted code? about probot HOT 4 CLOSED

If you want to be super paranoid you can use a separate process, but realistically the only way to get out of this sandbox is a V8 exploit (which is entirely possible ofc, but not trivial). I'd try to set up the environment s.t. if a user can escape the sandbox, they can only read secrets for their own repo (i.e. via chroots or sth)

from probot.

Contexts can share heap objects. Anything you pass into the PR script can have its prototype messed with, which is often an exploit vector.

Further more, anyone can call while(true){} and those are uninterruptible, and a DOS attack vector.

I think you'll want a 1-process per script model, and possibly use only c++ to pass in APIs to the untrusted script.

Since you don't actually need node APIs available for your scripts, you could also directly boot V8-Isolates in separate threads, and communicating via c++/libuv. Here's an old example https://github.com/groundwater/node-isolate-madness that would need updating, but it runs some JS in another thread and uses libuv to callback into the original thread.

from probot.

The DOS attack vector definitely requires separate isolates or processes, but you could write the trusted part of the code in JavaScript by taking advantage of an object-capabilities security model that was enabled by changes in ES5.

There's a talk about it from a member of Google's Caja team and a script floating around called initSES.js that supposedly enables this security model.

The basic idea is that you have to lock down a bunch of JS prototypes and other things to make it impossible, for example, to replace Array.push with your own nefarious version by following references to the prototype from an instance you were given and assigning a new method. If you do that and run untrusted code in an isolated context, you can still do trusted things outside of that context and maintain security.

from probot.

Thanks for the thoughts here. After #89, I'm going to kick this can down the road.

from probot.