1-Click GitHub Token Stealing via a VSCode Bug

(blog.ammaraskar.com)

157 points | by ammar2 13 hours ago

10 comments

  • antimony51 0 minutes ago
    > if you had some other XSS in a webview that you can get a victim to open, you get effectively full RCE on their computer.

    Github creds or the computer, can't decide which one is worse.

  • zbentley 1 hour ago
    This is a very good writeup.

    Zooming way out (perhaps to the point of useless observation), it's a pity that the web embedded VSCode editor is signed into GitHub at all. Defense-in-depth or not, a huge vulnerability surface arises from that original sin. It'd be like if you had a god-permissioned GitHub API token stored in world-readable plaintext on your workstation for the malicious-NPM-package-of-the-week to find.

    In a perfect world, it'd be awesome if the in-browser IDE launched with a temporary per-repo permission scope or token that allowed only pull and push to the repo in question; no github.com web session whatsoever. If you want the full GitHub web UI experience, well .... go back to github.com; make github.dev a single-repo service.

    I'm assuming that's a) inconvenient for users, b) hard to implement, and c) a historical assumption baked into a lot of the github.dev tooling, though. Ah well.

    • ammar2 1 hour ago
      > it'd be awesome if the in-browser IDE launched with a temporary per-repo permission scope

      That's actually exactly what they do for codespaces. The token only has read/write on the repo you activated for the codespace [1]. They should definitely consider doing that for github.dev as well.

      [1] https://orca.security/resources/blog/hacking-github-codespac...

    • amluto 46 minutes ago
      > temporary per-repo permission scope or token that allowed only pull and push to the repo in question

      How about pull from the repo but only push to a staging area from which the user, but not the token, can push for real?

      Frankly, LLM agents should do this too. Letting your LLM push seems foolhardy to me.

    • owl57 1 hour ago
      If the malicious-npm-package-of-the-week is reading arbitrary files on your workstation, isn't it usually able to run git clone/push/whatever with your current credentials anyway?
      • digi59404 1 hour ago
        Yes, but also no. For example in GitLab a user who’s infected could push code to a branch. Then it could even make a merge request to pull that branch into main (if main is protected).

        But then someone else on the team should have to manually approve that MR to allow it to be merged to main.

        This kind of defeats the ability of malware to push stuff out automatically.

      • ikiris 10 minutes ago
        Not if they're touch required in a secure enclave like a yubikey
  • zuzululu 4 minutes ago
    I had this happen to me recently

    github token got stolen and also cloudflare tokens

    guys even if you take security seriously you are going to get hit on a long enough time frame

    best thing to do is segregate and control damage

    trust no one, nothing, use orbstack, and always operate under the assumption that your token is going to get leaked at some point

    it knocked off my entire momentum. fortunately seemed like it was just a spam bot that took my tokens and created bunch of fake spam pages and trying to mine crypto

    the biggest feeling is the one of feeling violated

    take care fellow travelers

  • NagatoYuzuru 1 hour ago
    > the last time I interacted with MSRC regarding reporting a VSCode bug, it was a horrible experience where they silently fixed the bug

    Classic MSRC. It has figured out that researchers will report for free regardless. Why change?

    • guessmyname 34 minutes ago
      MSRC doesn’t fix bugs.

      I don’t know the specifics of this case, but I’ve managed bug bounty programs in the past through Bountysource and HackerOne. One thing that occasionally happens is that a report makes its way to the development team before the security team has fully assessed it, in this case MSRC.

      At that point, a developer may decide to quietly fix the issue. Sometimes that’s driven by a concern, rational or not, that being associated with a security bug could reflect poorly on them or affect future promotion opportunities. The result is that by the time the security team attempts to reproduce the report, the vulnerability is already gone.

      From MSRC’s perspective, all they see is that the provided reproduction steps no longer work. They have no visibility into the internal history of the bug or whether someone already patched it. As a result, the report gets closed as invalid even though the original finding may have been legitimate.

    • natpalmer1776 1 hour ago
      It was the status quo for a long time, then the pesky security researchers started asking for compensation instead of clout.
      • ammar2 1 hour ago
        > instead of clout

        I'm catching up on the infosec twitter side but it seems like it was even worse. A lot of people have the same story as me in 2023 of "they silently patch the bug and don't even credit you" which really stinks.

        • natpalmer1776 1 hour ago
          It definitely reminds me of the stereotypes of big business types stepping on the little guys to climb the ladder.

          I hope you get credit where credit is due in future endeavors.

      • opello 57 minutes ago
        Do it for the exposure! Artists of many stripes have had to combat that for ages.
  • Noumenon72 1 hour ago
    Thank you for essentially donating the time you spent on this exploit to raise awareness on improving VS Code's security response. You could have just given up on them but you're still trying to help.
    • ammar2 38 minutes ago
      Thank you, that's a very kind comment.

      I have no interest in selling these vulnerabilities or sitting on them. At the same time, it feels really bad to have a vendor disrespect the hours it can take to make a proof-of-concept by just patching it silently and not crediting you or acknowledging it.

  • pier25 1 hour ago
    The MSRC situation is really unbelievable.

    There are probably better sources but I think this video by The Primeagen is a good introduction.

    https://www.youtube.com/watch?v=9kxx5xp5nTQ

  • thrdbndndn 37 minutes ago
    Very good write up but I lost it a little at the end. Could someone clarify for me?

    The author said:

    You cannot just use the shortcut trick to install the evil extension directly because of new publisher trust system;

    You can bypass this by using local workspace extensions which has no publisher screening, but CSP blocks it;

    The solution seems to be that installing a local workspace extension which binds a shortcut of 'install extension without checking publisher'.

    So I assume it means:

    1. you need two extensions, 1st one is local and only for the keybinding, and 2nd one is the 'real' evil one and it doesn't need to (actually can't, because of CSP) be local anymore?

    2. the CSP only prevents the JS in local extension but nothing about its package.json (or the ability to add shortcuts), right?

    • ammar2 19 minutes ago
      1 and 2 are correct, take a look at the PoC repo here: https://github.com/ammaraskar/github-dev-token-steal-poc/tre...

      We can try to just put a `my-extension/extension.js` for the most direct execution but the CSP blocks that. It's only a script-src CSP blocking it though, so fetching the package.json is still kosher. So we end up using it to contribute a keybinding instead.

  • fg137 1 hour ago
    > To those folks, I am sorry, but this is one of the few levers I have to try to influence MSRC and the security posture of VSCode

    Someone is going to be blacklisted by Microsoft.

  • october8140 1 hour ago
    If you like VSCode but don't like Microsoft, try Zed (zed.dev).
    • ZeroCool2u 44 minutes ago
      Zed is excellent. I know it's weird, but the last thing holding me back is being able to have a browser based Zed session the same as VSCode.
  • vladsiu 31 minutes ago
    [dead]