### Author:  [@arianvp](https://discourse.nixos.org/u/arianvp)
#### Post date: [August 13, 2024, 6:27am UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/2 "2024-08-13T06:27:35Z")
Great find. This is scary.
I suggest we set up a branch protection rule in combination with CODEOWNERS that only allows specific team to merge Bootstrap files.
If GitHub isn’t rich enough to express this constraints we might need to consider making merge bot mandatory and encode it on there
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### Author:  [@Atemu](https://discourse.nixos.org/u/Atemu)
#### Post date: [August 13, 2024, 7:58am UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/3 "2024-08-13T07:58:00Z")
Would it be possible to verify bootstrap-files integrity using CI (i.e. ofBorg)?
A red CI would be a red flag (literally) to any committer.
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### Author:  [@Sandro](https://discourse.nixos.org/u/Sandro)
#### Post date: [August 13, 2024, 11:47am UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/4 "2024-08-13T11:47:54Z")
> [@arianvp](#):
>
> I suggest we set up a branch protection rule in combination with CODEOWNERS that only allows specific team to merge Bootstrap files.
I don’t think github allows that granularity. We would need to enforce that every codeowner needs to approve PRs they are owner for which doesn’t work with our current workflow.
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### Author:  [@Sandro](https://discourse.nixos.org/u/Sandro)
#### Post date: [August 13, 2024, 11:50am UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/5 "2024-08-13T11:50:14Z")
> [@Atemu](#):
>
> Would it be possible to verify bootstrap-files integrity using CI (i.e. ofBorg)?
There are issues for this already but ofborg development seems to be really dried out, so not sure if anything in that direction is going to happen.
[Make GitHub suggestions for fixing sha256 fields · Issue #429 · NixOS/ofborg · GitHub](https://github.com/NixOS/ofborg/issues/429) [Detect url/sha256 mismatch · Issue #647 · NixOS/ofborg · GitHub](https://github.com/NixOS/ofborg/issues/647)
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### Author:  [@hxtmdev](https://discourse.nixos.org/u/hxtmdev)
#### Post date: [August 13, 2024, 12:10pm UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/6 "2024-08-13T12:10:06Z")
This would be a good context to think about replacing widespread write access with a bot that does most actual merging again.
See [Automatic Merging Implementation · Issue #112 · NixOS/ofborg · GitHub](https://github.com/NixOS/ofborg/issues/112) and especially [Feature Request: Automatic merging · Issue #104 · NixOS/ofborg · GitHub](https://github.com/NixOS/ofborg/issues/104)
Direct write access for most users could be replaced by some kind of whitelist of users that can instruct the bot to merge IF all “must-succeed” checks (such as “no bootstrap file changes” or “only allow bootstrap file changes when at least 3 \ members approved”) succeeded.
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### Author:  [@amjoseph](https://discourse.nixos.org/u/amjoseph)
#### Post date: [August 16, 2024, 7:21am UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/7 "2024-08-16T07:21:02Z")
I believe [these two commits](https://git.sr.ht/~amjoseph/nixpkgs/log/pr/bootstrapFiles-attack-defense) prevent the attack:
- [testers.invalidateFetcherByDrvHash: move to lib.derivations](https://git.sr.ht/~amjoseph/nixpkgs/commit/07a907972aabfda14089d17adc6addd6903fd72a)
- [stdenv: bootstrapFiles: use invalidateFetcherByDrvHash on bootstrapTools](https://git.sr.ht/~amjoseph/nixpkgs/commit/40beef6268180dcb41f7c3455ef78a327b5fec90)
Currently building with this.
The defense works by wrapping the bootstrapFiles fetcher in `invalidateFetcherByDrvHash`. This requires that `invalidateFetcherByDrvHash` is moved from `pkgs` to `lib`, because we don’t have a `pkgs`-set so early in the `stdenv` bootstrap.
Needs to go to staging. Would appreciate comments from @trofi. Also needs approval from the `lib` folks for moving `invalidateFetcherByDrvHash` from `pkgs` to `lib` (which seems reasonable, since `invalidateFetcherByDrvHash` is totally standalone code that doesn’t use anything from nixpkgs).
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### Author:  [@emily](https://discourse.nixos.org/u/emily)
#### Post date: [August 16, 2024, 5:12pm UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/8 "2024-08-16T17:12:41Z")
I didn’t know about `invalidateFetcherByDrvHash` before, very interesting! I guess the docs should probably move too if the function does.
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### Author:  [@Mic92](https://discourse.nixos.org/u/Mic92)
#### Post date: [August 16, 2024, 5:33pm UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/9 "2024-08-16T17:33:22Z")
Yeah. We had also discovered this a while ago and I hat proposed to have a mitigation plan as part of a sovereign tech fund proposal, which didn’t made it into the final list.
Here is the idea: Have a CI job on master trying to download every new FOD from it’s url and if the hash mismatches, throw an alert for manual inspection. Bootstrap files are not very special I would say. Any critical dependency can be affected and cause damage. An attacker just must control any package and submit a malicious version that contains both the package to be updated and a different maliciously patched package.
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### Author:  [@ElvishJerricco](https://discourse.nixos.org/u/ElvishJerricco)
#### Post date: [August 16, 2024, 7:48pm UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/10 "2024-08-16T19:48:08Z")
Agreed; there are tons of packages that are _at least nearly_ as critical as the bootstrap files, like the kernel. Any solution should not be exclusive to bootstrap files, and just checking every FOD in CI or something seems like the way to go to me. There is the concern of FODs that are too resource intensive for CI, but I think those should just be flagged as failures, just like if it was a hash mismatch. That way someone knows to manually check it.
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### Author:  [@Infinisil](https://discourse.nixos.org/u/Infinisil)
#### Post date: [August 19, 2024, 3:51pm UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/11 "2024-08-19T15:51:41Z")
Lib folk here, sounds good to me! I’ll also get auto-pinged as a code owner when a PR is opened
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### Author:  [@amjoseph](https://discourse.nixos.org/u/amjoseph)
#### Post date: [August 22, 2024, 6:18am UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/12 "2024-08-22T06:18:00Z")
> [@Mic92](#):
>
> Bootstrap files are not very special I would say.
Well, they are the only binaries that are exempt from `NIXPKGS_ALLOW_NONSOURCE=0`.
They’re also the only binaries upstream of `stdenv`.
Sure, you could run this same attack on the `gcc` source tarball, but the exploit would need to be source code. This doesn’t make the exploit any easier to discover (it didn’t for xz) but _once discovered it makes it impossible to deny that an exploit happened._ For the bootstrap-files we don’t have that guarantee.
In any case I’m certainly in favor of applying this defense more broadly, but the bootstrap-files are where we really need it most.
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### Author:  [@marius851000](https://discourse.nixos.org/u/marius851000)
#### Post date: [August 30, 2024, 10:26am UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/13 "2024-08-30T10:26:15Z")
I wrote a script, and ran it on a few packages (`hello` and `libreoffice`), and it found no difference between the fetched derivation of FODs and their hash (outside of GitHub returning some temporary 403 errors, solved by retry). I’ll add a backoff retry logic, and share it for those who are interested to test other packages. It’s a python script directly calling nix commands.
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### Author:  [@boomshroom](https://discourse.nixos.org/u/boomshroom)
#### Post date: [October 4, 2025, 5:17pm UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/14 "2025-10-04T17:17:27Z")
This is why the work on the [minimal-bootstrap](https://github.com/NixOS/nixpkgs/issues/123095) project is so important. [Here’s the most recent PR on the subject that I could find.](https://github.com/NixOS/nixpkgs/pull/260193)
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### Author:  [@Lun](https://discourse.nixos.org/u/Lun)
#### Post date: [October 4, 2025, 10:33pm UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/15 "2025-10-04T22:33:13Z")
@pyrox has been working on it more recently
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### Author:  [@pyrox](https://discourse.nixos.org/u/pyrox)
#### Post date: [October 5, 2025, 12:37am UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/16 "2025-10-05T00:37:49Z")
I’ve been working on getting the existing packages updated and cleaned up a bit, and then will be taking the changes from the linked PR into my branch(with proper authorship maintained, of course), ensuring they work properly, and then will push all of that work through. Once that’s done, moving nixpkgs’ base from the existing bootstrap-tools files to these new bootstrapped derivations should be as easy as a derivation that creates the appropriate tarball, then substituted into the stdenv in place of the static tarball.
(note that while i say “easy as”, this is in reality still fairly involved and there’s a lot of work to do. However, this is something I expect could be done as soon as the 26.05 release(I am not making any promises, just guesses based on the speed of progress))
Note also that I am a college student doing this in her free time, and have other responsibilities in nixpkgs(25.11 release editor, package maintainence), and also do not want to work on a single project for months at a time, so I will be taking frequent breaks. I am trying to keep somewhat steady progress updates posted to the `#stdenv:nixos.org` matrix channel(Nixpkgs Stdenv) in the NixOS space, feel free to ping me there if you have any questions, comments, concerns, or would like to help!
Hopefully final edit: I 100% agree with the security concerns of trusting a bundle of static binaries, which is why I’m doing this! I do feel that this work has practical security benefits for nixpkgs users, and doing it gives us a more stable and trusted base to build off of. As a future cybersecurity major, doing stuff like this is why I got into the field, and it’s something I’m super passionate about, and even gave a very short talk at my university to a small group about why this work is important but also how difficult it can be.
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### Author:  [@siraben](https://discourse.nixos.org/u/siraben)
#### Post date: [October 5, 2025, 2:56am UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/17 "2025-10-05T02:56:56Z")
@pyrox saw your PR, thanks advancing the progress on minimal bootstrap. Feel free to ping me if you need me to do `nixpkgs-review` on packages made with this bootstrap, I have a beefy build machine lying around.
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### Author:  [@pyrox](https://discourse.nixos.org/u/pyrox)
#### Post date: [October 5, 2025, 3:02am UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/18 "2025-10-05T03:02:02Z")
I’ve been doing all this bootstrapping on my laptop!(It’s a modern laptop, but still, doesn’t need a build farm thankfully) Since it’s not the stdenv root at the moment, it’s fairly light and easy to build(you can build the whole thing in probably around 20-30 minutes by checking out the pr and running `nix build -f . pkgsi686Linux.minimal-bootstrap.test`!)
Edit 2: You will need to run `nix build -f . make-minimal-bootstrap-sources` first, then the above command. Weird bootstrapping thing that’s unavoidable. But those two commands build up the entirety of the package set from the PR!
Edit 3: For those interested, the PR: [minimal-bootstrap: lots of updates by pyrox0 · Pull Request #448701 · NixOS/nixpkgs · GitHub](https://github.com/NixOS/nixpkgs/pull/448701)
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### Author:  [@rnhmjoj](https://discourse.nixos.org/u/rnhmjoj)
#### Post date: [October 5, 2025, 7:31am UTC](https://discourse.nixos.org/t/bootstrap-files-updates-amplifiy-exploit-of-any-package-into-exploit-of-every-package/50534/19 "2025-10-05T07:31:38Z")
> [@amjoseph](#):
>
> use the storepath-hash of the exploit as the `hash` argument of the `import ` call. Hydra won’t bother trying to download from `tarballs.nixos.org`
Is there a way to prevent this?
Just the other day I was updating some pins in my configuration, but I accidentally swapped two hashes: Nix happily built my system with `` pointing to `` consequently breaking every nix command.