Not sure how Vim and Sublime work, but for Emacs, publishing to MELPA is absolutely a push process, where you open a PR to MELPA's repo with a recipe for your new package; and, once it's accepted, every commit to your repo results in a new package build on MELPA's servers that Emacs users will get when they update / install the new plugin.
It’s not. The developer never build a package and then upload on melpa. Melpa will fetch the needed files and build the package. It’s not truly secure, but an attacker would need to publish a new commit and wait for quite some time for people to update.
Another thing is that some packages are old. Seeing an update out of the blue would be very strange. And for packages that are updated more often, I guess the maintainer would be quite surprised to see a new commit they’ve not approved of.
My point is, if I want to create a malicious Emacs plugin, I can do the following:
1. Create a new Emacs package, create a PR to register my GitHub repo as a new package in MELPA's repo, and wait for them to accept the PR. Ideally the plugin should be benign at this point.
2. Wait for people to pick up this new extension, while it's still benign.
3. Push the malicious version to my own GitHub repo. MELPA will automatically pick it up, build it, and package it.
4. Anyone updating their Emacs packages from MELPA or installing it from MELPA will pick up this malicious version.
Now, this does require that the malicious code is visible on the extension's GitHub page; I'm not sure if this would be true on VSCode as well.
> 2. Wait for people to pick up this new extension, while it's still benign
Good luck on that. Check the most popular packages and they all belong to fairly well known people in the community. If it’s something small, people usually just copy the relevant bit to their config. And rarely do huge systems pick up users without active advocacy (helm, ivy, vertico, company, magit, consult, hyperbole, emms, org-mode,…) which means collaboration and plenty of people looking at upstream.
Sure, but this is just an accident of Emacs being a much more niche product, not related in any way to the design of the package system. If Emacs suddenly gained VSCode's popularity, I can assure you that numerous new users would simply look through MELPA and pick up packages that sound useful, and quickly end up picking up malware - nothing in Emacs prevents this any more than VSCode.
> I can assure you that numerous new users would simply look through MELPA and pick up packages that sound useful, and quickly end up picking up malware
But the issue is not new users picking up unconfirmed packages. It’s about active employees getting compromised by extensions they trusted. As the nature of packages update is opaque and the default settings leave you vulnerable.
If you go on magit’s page on melpa, you get the commit id used for the build and if you wanted too, you could diff the files with upstream. Everything is transparent. Meanwhile what you got on marketplace is whatever is pushed by a token.
And another nice thing about packaging system like emacs is that they rely on peer dependencies instead of pulling their own from the internet. Which is nice, because when a bug is patched, you update that single dependency and you’re done. No need to update every package that depends on it.
Transparent doesn't mean secure. The very source of this issue was a recent NPM supply-chain attack, and you can also check the sources of any NPM package that you use. NPM also relies on peer dependencies, and this is exactly why malware spreads so efficiently in the ecosystem - just like it helps spread bug fixes, it also helps spread malware as efficiently.
Very, very few people, even in tech circles, check the sources of all of their dependencies. Sure, compromising magit's sources will be hard - but you don't need to compromise magit. Just compromise one of magit's dependencies and watch the malware spread.
Edit: in fact, you don't even need to compromise Magit's dependencies. Since the developers of Magit probably use Emacs themselves, you can probably just compromise some small Emacs package that happens to be used by someone on the Magit team, get access to their repo from there, and then you actually may be able to compromise Magit itself (depending on how strict their code review etc rules are).
