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Comment by skinfaxi | Hacker News Reader

The agent has no access to the secret. It has a placeholder that is replaced at a higher level. When it makes the network request the secret is substituted but that is outside of the caller's worldview.

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So what stops it from sending a network request to a git repo that pushes what that placeholder resolves to?

How would that work? You don't control github.com servers so your repo would never see the secret.

edit: You may want to look into tokenizing proxies as the general application of this concept.

Your agent writes secret.txt with the placeholder, and the tokenizing proxy replaces it with the token, then the agent reads secret.txt

It only replaces the token in the HTTP header that is sent to the server. Whatever you wrote in your files isn't touched by the proxy.

It sends a request to requestb.in and reads the public log of the headers. There are ways.

But requestb.in is not api.github.com so the proxy wouldn't replace anything.

Maybe the tokenizing proxy could work both ways? If the agent tries to read secret.txt, it gets back the placeholder.

Couldn't it then just publish the mock in a public place... it would get replaced by the real secret.? How is this prevented

But how? Normally the TLS handshake and encryption/decryption happen in user space. Even the kernel doesn’t know anything about it.

There is a transparent proxy installed (along with the necessary certificates on the VM.) For an example, see https://docs.microsandbox.dev/networking/tls

So, if the program or the proxy solution doesn’t support it, then it doesn’t work? Like with security solutions?

The docs mention it can be bypassed for configured domains.

Yes, I read it. That means that it doesn’t work in those cases. Btw, as a developer it’s very easy to have something like that. It’s not as trivial as it seems at all. I encountered with similar problems all the time, with similar solutions (mainly for security theater reasons) in the past. There are websites which simply doesn’t work if you replace certificates, regardless of browser or CA for example.

Yes, I've worked with people who have run into issues with "security" solutions like ZScaler. I have tried it with some APIs (like GitHub) and it does work. Not to say it will work in your case.

I was just interested how it works, because above it was sold as “it works”, when in reality, “it works*”.

Isn't it that way with most software? "It works", except when it doesn't.

There is a difference between bugs/failures, and false advertisement. The solution used here has well known shortcomings.

All SSL/TLS interception has the shortcoming. In other contexts, that’s a good thing, when certificate pinning works, I mean.

microsandbox is designed to work with most security products. there's a dedicated section for this in the docs that makes this entire process seamless: https://docs.microsandbox.dev/networking/tls#trusting-host-c...

microsandbox maintainer here. the custom certificate is installed in the guest's trusted root CA list, so it should work across any program, except where the program opts to explicitly pin certificates for a destination.

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