Yet another Hacker News

Backdoors in official Claude Code extensions

322 points dsr_ 1 hour ago 82 comments

hem777 1 hour ago | parent

”I've confirmed Binance use Claude Code with this extension.”

fn-mote 1 hour ago | parent

^^ Had to verify that this was a real quote from the chain and not a joke. It is accurate.

xx_ns 1 hour ago | parent

I think it should be important to note that this affected the Claude Code extension on the Open VSX extension registry (and by extension, the Cursor marketplace). From what is currently known, the build on the official marketplace was/is clean.

EDIT: I am now actually unsure if this is the case. From what I can see, all of the write-ups mention the Cursor marketplace and Open VSX specifically, but make no explicit mention of the official Microsoft registry.

thevinter 1 hour ago | parent

Do you have any sources? OP claims that it *also* affects Open VSX

Hackbraten 13 minutes ago | parent

Three different marketplaces have been mentioned in this discussion:

1. The Cursor Marketplace (never heard of this one, it’s possibly a custom marketplace hard-wired into Cursor, which is architecturally a VS Code fork?)

2. The Visual Studio marketplace, hard-wired into VS Code

3. Open VSX

If I understand this thread correctly, then #1 and #3 had compromised versions, and nobody has made a statement yet about the status of #2.

xx_ns 13 minutes ago | parent

I assumed they meant "also" as in "besides Cursor marketplace", which seems to be the highlight of the article. Although you raise a valid point and I've edited the parent comment.

tveita 10 minutes ago | parent

But the report OP cites at https://phorion.io/blog/offical-claude-code-vsx-compromise/ doesn't make a claim about Visual Studio Marketplace, only "the official Claude Code for VS Code extension bundle on the Cursor Marketplace"

mrweasel 1 hour ago | parent

You mean on the Microsoft VSCode marketplace? The version has been yanked from there as well, but that could just be a precaution and to avoid confusion about having the same version be simultaneously infected and not infected.

This very much illustrates the danger of just carelessly installing untrusted software on your machine. In this case it happens to be code from Anthropic, but it could have been almost anyone. I'll be very interested in see the explanation from Anthropic, because of all the extension developers they should have the best tools for finding issues like this. LLMs have proven pretty good at finding security issues, so did they simply not let their own AI tools vet the code before shipping it? Or was the extension infected later, because in that case every single extension on Open VSX could be at risk.

eviks 1 hour ago | parent

What would be the careful way of installing the official extension?

mrweasel 44 minutes ago | parent

That is a really good question, because you almost can't do it. You could download the extension, diff it against the previous version and read all the code. Expecting people to do that it just a bit much. At some point we have to trust someone and in this case it will be interesting to see if it's the marketplace or Anthropic we couldn't trust.

toyg 18 minutes ago | parent

> You could download the extension, diff it against the previous version and read all the code.

This would actually be an exceptionally good use-case for AI. You don't need a super-duper frontier model to download a bit of source-available code and check for suspicious signs, any cheap model would do well enough. Heck, it's effectively virus scanning, we've had that for decades.

misnome 1 hour ago | parent

The screenshot is of the official marketplace

nubinetwork 1 hour ago | parent

It looks like they push an update every office day. I'm guessing if I installed 6 months ago and didn't update, that I should be fine?

fn-mote 1 hour ago | parent

Emphasis on guessing. If/when there is an actual postmortem, you’ll know when the back door was introduced.

fg137 1 hour ago | parent

You are either lucky or compromised.

koolba 1 hour ago | parent

Not updating air gapped systems is a security feature, not a bug.

staminade 50 minutes ago | parent

I think VS Code extensions autoupdate by default, unless you disable it.

entrope 39 minutes ago | parent

Yes, but they normally have a 12-hour delay (it was 2 hours at the beginning of June and got extended sometime after that, maybe later in June) and require some human action to reload extensions or restart the editor before the new version runs.

I noticed that there was no update yesterday and wondered why. The daily updates are annoying in the base case.

Edited: This update was live for only 11 hours, so hopefully the default delay limited the blast radius, as it is meant to do.

altbdoor 1 hour ago | parent

Cursor has released a security notice:

https://cursor.com/blog/claude-code-extension-security-notic...

sharpshadow 36 minutes ago | parent

Looks like a solid response with instructions and scripts how to get rid of the infection, but it doesn’t explain how it got there.

yubblegum 30 minutes ago | parent

> Cursor: "This malicious version of the extension was not developed by Anthropic."

Wtf does that mean.

sourcecodeplz 28 minutes ago | parent

someone got access to the account that can publish extension on cursor marketplace?

noitpmeder 27 minutes ago | parent

Just by people they paid to represent them.

olmo23 21 minutes ago | parent

It sounds to me like they're saying it wasn't an Anthropic employee which decided to drop an SSH backdoor.

eviks 1 hour ago | parent

That's literally impossible, with all the access to the frontier software development tools at their disposal they can ship features securely at 100x

kamban 58 minutes ago | parent

Yet, they managed to screw up.

iugtmkbdfil834 48 minutes ago | parent

:D I have to assume parent is being a little sarcastic.

It obviously doesn't take much to simply add 'just one more feature' that happens to undermine the original purpose of the application.

skydhash 40 minutes ago | parent

It always about “we solved the bottleneck in coding”. But the slowness was not about typing, or finding docs. It’s always about ensuring screwups don’t happen.

mirekrusin 4 minutes ago | parent

To be fair it’s not like screwups were not happening before, but if you move 100x faster and are 50x more secure than before you’re still 2x more exposed.

atrokhymchuk 34 minutes ago | parent

I am afraid until 200x is achieved we are at risk...

btown 26 minutes ago | parent

Only with two fully maxed subscriptions can we achieve this, and this is forbiddeneded

samiv 23 minutes ago | parent

Just put gastown on it!

stymaar 21 minutes ago | parent

I read a few month ago a comment from an Anthropic or OpenAI employee saying that the security problem of prompt injection was a solved problem at this point, as the frontier models where rejecting 98% of attacks.

It tells you all you need to know about how unserious these people are about computer security.

malfist 19 minutes ago | parent

I'm glad no one can steal from my bank, they stop 98% of thieves

stopsayingsorry 1 hour ago | parent

Imagine backdooring 50+ million installs.

Hats off to the hackers.

stbenjam 1 hour ago | parent

5,000*

gcoakes 39 minutes ago | parent

I think that's just the number Cursor has telemetry on. I think there's multiple distribution locations.

misnome 37 minutes ago | parent

5000 is the cursor number for people on the cursor version of the store, not the VSCode store.

misnome 57 minutes ago | parent

Has anyone managed to confirm the time that the backdoored version was released? None of my machines updated to it, I am wondering if it was saved by a combination of luck and

> This extension is not updated yet because new versions become eligible for automatic update 12 hours after they are published. It will become eligible in 2 hours.

anon-3988 49 minutes ago | parent

I have this realization recently that everyone that uses Claude Code or Codex have basically been running RCE code on a daily basis (me included). So much for "be careful about running curl | bash!". That puts it into perspective what does security and privacy really mean? For all I know, these CLIs could have been secretly scraping my entire directory. Who's checking?

staminade 44 minutes ago | parent

This was a compromise of the extension. The same kind of supply-chain attack could happen to literally any extension, package or other piece of software you install. Not excusing Anthropic letting this happen, but it doesn't have any bearing on the security and privacy of using Claude Code or Codex. Yes, you need to be careful about what they do. The fact that you might still get pwned via some other vector is irrelevant.

minraws 27 minutes ago | parent

Can't their millions of agent swarms detect a malicious supply chain vector, sure it can happen to any company but not the one people are literally handing over their entire companies too.

Anthropic holds the SLA/MSA agreements not this bad actors what happens to your data is unknown if these become frequent and accepted. Given how much data is piped to Claude code via these services/extensions.

Den_VR 43 minutes ago | parent

There’s a reason codex and the like improved like they did. You can simply look. Or hear about it on podcasts.

snaking0776 43 minutes ago | parent

In at least one case they were! https://cybernews.com/ai-news/grok-build-git-repository-uplo...

origini 34 minutes ago | parent

Don't forget: To make LLM useful you give it EVERYTHING it needs to know to be useful and if you don't use a certain provider with proper legal status, this is just gone.

We probably transfered more code/codebases and company secrets to random endpoints than ever before.

Btw. you could setup a sandbox and limit access

raxxorraxor 18 minutes ago | parent

Both is completely secure theoretically. You can read the output of the curl before you refetch and pipe it to bash. You can also look at the commands claude is executing.

You always do that, right? ...right?

deadbabe 12 minutes ago | parent

No but we use MCP so we’re fine.

novafunc 2 minutes ago | parent

I used to think the same, but apparently there's a way to differentiate between curling into bash and curling into a text file.

So you could be diligent and curl into a text file, see nothing is wrong, but then when you curl into bash, it runs something different.

magnio 15 minutes ago | parent

> Who's checking?

Yeah I sympathize with people saying software developers should not be called engineers too.

palata 10 minutes ago | parent

I think that software engineering is very much engineering.

I just think that the level of malpractice in software engineering is a lot higher than in other engineering fields, for some reasons.

AdrianCX 47 minutes ago | parent

https://www.reuters.com/business/media-telecom/cursor-says-u...

> Cursor said the extension was not developed by Anthropic and the maliciously modified extension was live on the marketplace from about 2:27 a.m. PT to 1:35 p.m. PT on Thursday

So is this or isn't this from Anthropic and how did this happen?

iugtmkbdfil834 46 minutes ago | parent

Isn't it fun when all the lines are blurred and it is hard to tell what belongs where?

darkwi11ow 39 minutes ago | parent

It was likely Anthropic, see my comment in other thread: https://news.ycombinator.com/reply?id=50302513&goto=item%3Fi... . Cursor likely on purpose does bad reporting to minimize damage on Anthropic pre-IPO (as SpaceX and Anthropic have extensive business ties)

origini 35 minutes ago | parent

I don't think Spacex cares at all about Anthropics IPO just because they rent out their compute.

Big companies are not just 'Company' they are a lot of small teams doing their own things. They need to coordinate with other people for public announcements etc. and security team is probably also looking at it.

stopsayingsorry 29 minutes ago | parent

People at the top know that, once the music stops, the ball is over for everyone.

AdrianCX 27 minutes ago | parent

OpenVSX has no extension signing, no verification, nothing...

So really, there's no way to say what was compromised and where.

This could have been avoided by having extensions signed by company doing them with their own keys and have them reviewed

mrweasel 36 minutes ago | parent

Obviously Anthropic didn't develop a malicious extension, but did they publish it? Did it sneak in, in a 3rd party library, or does someone have access to their marketplace account?

HexDecOctBin 41 minutes ago | parent

> Claude Code for VS Code extension on the Cursor Marketplace

So Cursor is running its own extension repository? Or is this the official VS Code repository and the incident report just happens to focus on Cursor for some reason?

NewsaHackO 38 minutes ago | parent

VS Code doesn't allow forks to use their marketplace, I think. At least with VSCodium, they don't. I think they even patch a workaround where you could download almost all extensions' .vsix files.

altbdoor 28 minutes ago | parent

1. If only Cursor Marketplace version was compromised, how was it published in the first place?

2. If the Cursor Marketplace version was released from an "official Anthropic" account, whose to say OpenVSX and/or VSCode versions are not compromised?

The affected versions have been pulled down, so no one really knows. The way I see it, only Cursor has admitted to have been compromised.

stbenjam 40 minutes ago | parent

We still don’t know exactly what happened, but I publish software to public registries, and supply chain attacks scare the hell out of me. They also frustrate me, because most of the defenses aren't automatic and often really hard to get right. We're really failing as an industry to do better here.

poelzi 34 minutes ago | parent

This is why I started to move more and more into my tix.im environment. You can't trust anything anymore - I assume everything is compromised if not proven otherwise.

poelzi 36 minutes ago | parent

I guess, this is why I'm building tix.im ...

orlp 27 minutes ago | parent

So if this happened to OpenAI it would've been instantly auto-updated everywhere? VS Code has an "auto update delay" which I have configured to a week, but I just found out that (https://code.visualstudio.com/updates/v1_123):

> Note: This delay does not apply to extensions from trusted publishers such as Microsoft, GitHub, and OpenAI. These extensions continue to update immediately.

You can't even configure which publishers you "trust"...

numbsafari 25 minutes ago | parent

This puts an entirely new spin on Elon trolling Binance on Twitter.

efficax 18 minutes ago | parent

either the registry is compromised or someone at anthropic got compromised (or did it on purpose to steal crypto). the line in the cursor disclosure about the extension not being developed by anthropic is more confusing than clarifying. amateur hour for these massive corps

rvz 5 minutes ago | parent

This is embarrassing to Anthropic given here that they lack basic security procedures to prevent this and they have gotten themselves hacked to push malware.

Claude Code was already malware, but with this attack you cannot trust the vendor either.

In the next 2 weeks, no one should download / install / update anything as I predict at least one developer's key for a GitHub, NPM, Crates.io or any other CI or login was leaked and the attacker will target those services to propagate their trojan to more victims.

yubblegum 5 minutes ago | parent

The original Phorion report really should be up here. It even details what exactly happened. So they simply add add a ssh key to the authorized keys.

https://phorion.io/blog/offical-claude-code-vsx-compromise/

anonymous908213 3 minutes ago | parent

If it is true that Binance was compromised as a result of this, hats off to our new billionaire friend for one hell of a heist.