Comment by perbu
9 hours ago
Want to verify the installed package, the package should provide checksums you can verify. AFAIK, the SBOM is to documents the build, not the install.
9 hours ago
Want to verify the installed package, the package should provide checksums you can verify. AFAIK, the SBOM is to documents the build, not the install.
The checksum just tells you what the hash is, nothing more. Supply chain attacks aren't always against the main executable either. With authenticode, the "catalog" can be signed. You're even more opposite of OP than I (OP proposes lockfiles which are at runtime).
It shouldn't be for "just" any state of the software. We should be able to verify SBOM and take actions at any point. At build time, it is only useful for the developer, I don't get why SBOM is relevant at all. I think you mean at deployment time (when someone installs it - they check SBOM). What I'm saying is, when you fetch the software (download, package manager, appstore,curl|sh), when you "install" it, when you run it, and when it is dormant and unused. At all of those times, SBOM should be checkable. Hashes are useless unless you want people to collect hashes for every executable constantly, including things like software updates.
The problem is, people are looking at it only from their own perspective. People interested in audits and compliance don't care about runtime policy enforcement. People worried about software supplychain compromises, care more about immediate auditability of their environment and ability to take actions.
The recent Shai-Hulud node worm is a good example. Even the best sources were telling people to check specific files at specific locations. There was just one post I found on github issues where someone was suggesting checking the node package cache. Ideally, we would be able to allow-list even js files based on real-time SBOM driven policies. We should be able to easily say "if the software version is published by $developer between dates $start and $end it is disallowed".
I still don't see how lockfiles can't be SBOM.
They contain for each dependency name, version, (derivable) URL and integrity checksum, plus of course the intra-dependency relationships.
This can all be verified at any point in the lifecycle without running any of the code, provided a network connection and/or the module cache. What's missing?
> With authenticode, the "catalog" can be signed
You could trivially sign any lockfile, though I've never seen it. I think it could be neat and it might have a chance to catch on if there was more support in tooling for it. The NPM registry does support ECDSA package sigs but I guess signatures for this use should be distributed on other channels given how much of an antipattern uploading lockfiles to registry is considered in the npm community and that's an uphill. In the context of SBOMs I guess there's already a slot for it?
I don't think you've addressed the requirement of having to execute the software, that was my main objection.
Another matter is that most software I know of doesn't even use lock files. Furthermore, there are lots and lots of software that would need to be updated to support your scheme, but updating them just isn't practical. It would have to be relegated to the type of software that gets regularly updated and its authors care about this stuff. I mean, we can't even get proper software authors to host a security.txt on their website reliably. It needs to work for "old" software, and "new" software would need to spend time and effort implementing this scheme. How can we get people that won't even sign their executable to sign a lock file and participate in the verification process?
Ah, but there are actually different types of SBOMs, that describe the software in different parts of its lifecycle. It's a completely different outcome to record the software when looking at its source, at what is being distributed, or at what is being installed, for example.
At some point we realized that we were talking across each other, since everyone was using "SBOM" to describe different contents and use cases.
The consensus was expressed around 3 years ago, and published in https://www.cisa.gov/sites/default/files/2023-04/sbom-types-...
I haven't had a chance to read that, but do you think it would be impractical to have the different types of SBOMs declared in a standardized format? My impression is that no matter what, authenticity needs to be established, so it will always fall under "cryptographic verification of information about software", it is the standardization of that which I have an issue with.