Because it does. The attack has to involve the CI pipeline rather than the dev environment, there's no token to revoke after (if you evict the attacker you're done, the OIDC credentials expire), it's easier to monitor for externally, you can build things like branch protections in and isolate things like "run tests" from "publish", etc. Trusted Publishing is not itself a solution to all supply chain issues but it is a massive improvement.
I agree with you that TP is an improvement over long lived npm tokens in CI.
However, the threat Im most afraid of still does involve dev environment compromise. Because if your repo admin gets their token stolen from their gh cli, they can trivially undo via API (without a 2fa gate!) any github level gate you have put in place to make TP safe. I want so badly to be wrong about that, we have been evaluating TP in my projects and I want to use it. But without a second factor to promote a release, at the end of the day if you have TP configured and your repo admin gets pwned, you cannot stop a TP release unless you race their publish and disable TP at npm.
TP is amazing at removing long lived npm tokens from CI, but the class of compromise that historically has plagued the ecosystem does not at all depend on the token being long lived, it depends on an attacker getting a token which doesnt require 2fa.
I am begging for someone to prove me wrong about this, not to be a shit, but because I really want to find a secure way to use TP in lodash, express, body-parser, cors, etc
Yes, that is the threat I'm most worried about as well. But look at your description of it - a repo admin has to be compromised. Not just "random engineer". Although, in this case, the attacker leveraged a cache poisoning attack to move into the privileged workflow and I suspect this sort of thing will be commonplace.
I'm in agreement that a second factor would be ideal, to be clear. I think it's a good idea, something like "package is released with Trusted Publishing, then 'marked' via a 2FA attestation". But in theory that 2FA is supposed to be necessary anyways since you can require a 2FA on Github and then require approvals on PRs - hence the cache poisoning being required.
Not to beat the dead horse, but ths floored me when I realized it so I keep trying to shout it at the top of my lungs.
There is no gate you can put on a Trusted Publisher setup in github which requires 2fa to remove. Full stop. 2fa on github gates some actions, but with a token with the right scope you can just disable the gating of workflow-runs-on-approve, branch protection, anything besides I think repo deletion and renaming.
And in my experience most maintainers will have repo admin perms by nature of the maintainer team being small and high trust. Your point is well taken, however, that said stolen token does need to have high enough privileges. But if you are the lead maintainer of your project, your gh token just comes with admin on your repo scope.