I did a technical review of our Jenkins solution with a friendly neighborhood InfoSec agent once. He was interested in a few things:

1) how is the stored credential being encrypted (is it encrypted at rest),

2) is it real encryption (like, does it use an actual encryption algorithm or is someone confusing base64 or rot13 for encryption)

3) where is the encrypted data stored, where are the keys stored, is it properly on a machine that is not situated directly on the internet (users must access through VPN)

4) can I review the code that decrypts the secret (yes you can, there are plenty of walkthroughs and gists published by many different Jenkins fans and users that show where Jenkins stores its encryption keys, and how you can borrow them with POC code you can use to decrypt individual creds or even the whole store, assuming you have admin access to Jenkins)

He didn't really ask or care about sandboxing at all. There are mitigations you can apply for any threat model, but the crux of the matter is that even InfoSec assumed that any Jenkins users would probably have admin access anyway, and that they should all be allowed to decrypt those secrets.

Which happens to be exactly what they tell you in articles about how to manage your Jenkins server anyway:

https://www.codurance.com/publications/2019/05/30/accessing-...

> 7. Treat all credentials stored in Jenkins as plain text

> Treat everyone with access to Jenkins as an admin user, and you will be fine. Once you give someone access, even read-only, to a Jenkins it's game over. All developers on a project should know all secrets anyway.

The sandbox is just a mitigation that has been built in so that people who run untrusted code can do so with some degree of safety. Jenkins servers that may be exposed to untrusted contributors are a completely different animal than internal Jenkins servers. Different use modes experience different threat models differently.

The fact that you seem to believe there is a technical mitigation possible which would save this is potentially part of the problem, too. You're obviously a well-educated person. Organizations of sufficiently large size that settle on Jenkins can fight an uphill battle here, since many mitigations can only reduce risks, but cannot eliminate them. Leadership roles may not be inclined to understand the threat model issue, there is a dichotomy experienced when Jenkins is used to build software in the open vs closed developer models. Running builds for any PR from a random fork of a public repo is not the same threat model as running builds for any branch or tag in a private repo, from an IC with write access. And yet the mechanical actions are quite the same, and there are only about two checkboxes in a typical configuration separating these models from each other.

I hope we are rapidly reaching a place where companies can participate in both Open and Closed style of development, but if they are supported by Jenkins, I hope it's at least two separate Jenkins servers, because the threat models and risk mitigation that are needed for closed-access teams and open-source style public benefit repos are both completely different, even if their activities are not different.

Maybe I am overstating the risks, but I have been a Jenkins admin before, when it was not in my job description, and it was not supported by leadership, who did not believe in the benefits of open development, and made their posture closed by default (as companies are often wont to do.)

And as a result, I'm afraid, before I left that job behind, we dug the hole so deep in the wrong direction... if I could go back and do it again, I would certainly draw some bright lines in different places than we did, and I would not allow customer data in the dev instances. (You can do that kind of testing in a staging environment, where similar controls as production can be applied and reliably maintained. But you should do this as far away from Jenkins as humanly possible!)