yeah but they can just put the dropper, etc in index.js, so that it runs at import time rather than at install time, no? i guess first-install time is often a privileged developer machine, and will execute in a "server"-like runtime such as Node, Bun, Deno. but blocking preinstall scripts is basic first aid...
Nobody is claiming this is a complete solution to security. I would call this "necessary but not sufficient". You won't get far as an engineer if you refuse to implement "necessary but not sufficient" changes because the change doesn't in and of itself one-shot the entire problem.
These half-measures is why everything has gone to shits. Instead of properly auditing software, reducing the quantity and increasing the quality, we keep pushing more and more garbage where all you find is 2FA that, captcha this, not supported this, app not signed, etc..
Can't agree more. I'm working on OSS security tool that can protect you from Shai-hulud, no half measures.
The idea is to have a local proxy that injects real secrets into requests in-flight, so a compromised library has nothing to steal because it never had access to any of your secrets: https://github.com/inflightsec/agent-vault-proxy
Defense in depth is the “meat and potatoes” of security.
In other words: people should be auditing their software, but we should also design systems and schemes that provide varying degrees of defense and protection when people invariably fail to review the code they run.
Defence in depth is not just 'throw anything in that might improve security' though. The idea is to have multiple strong layers, not a hundred half-measures that are all easily bypassed. A stronger layer might be sandboxing, or separating your build and publishing steps as others have suggested (and also probably worth restricting the credentials the publishing step to just the relevant packages as well). These will at least robustly prevent a malicious dependency from spreading horizontally, but you'll still potentially ship malware to your customers.
The fact that it's not sufficient also largely means it's not necessary either, because the real solution is auditing and trusting the codebase as a whole. All you do when disabling install hooks is make a lot of situations much more difficult to handle.
You will also not get very far in engineering if you have a production incident, someone proposes a thing that will mitigate it partially but significantly, and you insist that we can't deploy that mitigation because we need to do the multi-year project that will actually fix it instead. Even if we still need that project, we also need that mitigation.
Sure, solve the problem of "auditing and trusting codebases". Go for it. Shouldn't take you until, oh, let me be generous and give you until next Monday. No sweat.
Feel free to turn it off yourself, just don't be surprised when the attackers switch tactics. And don't make life harder for everyone else by pushing it as mandatory.
(if you want a better mitigation: don't automatically update dependencies in CI. At a minimum have a cooling-off period that you only bypass on manual review. This is not hard to implement and at least gives some time for alarm bells to be sounded before you're pwned. Probably while doing the updates you can also just do a quick sanity check on the changes, that'll also catch the ones using a blatant install hook)
> if you want a better mitigation: don't automatically update dependencies in CI. At a minimum have a cooling-off period that you only bypass on manual review. This is not hard to implement and at least gives some time for alarm bells to be sounded before you're pwned.
One of the problems a lot of companies are having right now is trying to determine a proper window size between CVE release and patching.
On one hand, you have LLM created 0days and attacks are happening almost as fast as CVEs can be posted, and CVEs are being posted at lightning speed. You maybe had a month or a few weeks to patch before, now the window may be down to days or even hours.
On the other hand, you want to prevent these repo bombing attacks.
There's a tension there but I think we're going to end up measuring that window in hours within the year, if we're not already there.
If you need quick responses to such things, you're gonna need some intelligence in the loop regardless, even if it's just deciding when it's worth pushing a new release to prod.
Always has been, arguably. Either way I don't think most people have their CI configured to automatically re-run when a dependency updates (imagine the thundering herd!), the compromises are more incidental to runs happening for other reasons, and that configuration neither guarantees a quick response nor protects against supply chain attacks.
(If you find you do need updates when you're sleeping, you probably need to delegate that process or at least the process of checking the update to someone you trust, and you're probably paying for the service. This blog post is in large part an ad for just such a service).
Neither is 'close the gate with no fence on either side of it'. If you want to run code, you either need to run it in a sandbox or trust it. Choosing to run only part of the code is not really a solution.
(if you want to disable such hooks yourself, then you may get some security by diversity because you're not using the common configuration. But if it becomes the default then these worms will switch to a different vector)
Prod tends to have less privileges than CI/CD. CI/CD tends to be full admin, so it's far more sensitive. Prod tends to have tooling for detecting breaches, better logging, etc. People tend to use containers, which act as a sandbox.
Prod also won't be wormable the way that CI/CD is. With CI/CD I can own another dev, use their creds to push another malicious build script, etc. "Attacker is in my prod env" isn't wormable.
Yes, capabilities in prod would be hugely beneficial but removing CI/CD is massive as a win.
Dev laptops tend to have better monitoring than CI/CD so I still think this is a better option. You can also have devs use VMs or separate dev environments like an ec2 instance.
To be clear, just solving the CI/CD portion is insufficient, but it is a massive win.
iirc does pnpm not allow them by default. But even if we killed them off there would still be a chance of the malware hooking into something else or only working in cli applications.
You'll just end up with people running `./configure` scripts or whatever instead. The solution I've currently landed on is:
1. Audit build scripts/ proc macros for rust code (and mark with cargo-vet).
2. Have an isolated workflow for "build/test/push artifact to temporary place" (s3, github artifact, whatever). No API keys in this workflow.
3. Have another workflow that has the API keys to publish that grabs the artifact and then places it into a registry.
This creates clear separation of "code runs here" and "environment has privileges".
In my own slop-driven programming language I have build scripts declare their capabilities upfront so that you can statically reason about them (same with runtime permissions).
It sucks that we have this glass-jaw dependency system, which is really the main reason these supply chain attacks work.
Really hard to clean up, too. These days, you (being the blackhat) would likely send agents to leverage every compromised repo/app/Web site, almost the instant it comes online, so even if the original mess is cleaned up, there's still a ton of knock-on compromises.
Does anyone happen to have a grep or similar that helps me check if this is showing up anywhere in the trillions of files in node_modules (or pnpm store)?
The what happened section mentions the addition of the `setup.mjs` and `Math_Symbol.js`, along with a change in `package.json` to add `"preinstall": "node setup.mjs"`, so presumably checking for any of those would be a good indication to check further.
can you search all installed node modules for any sign of the shai hulud supply chain attack? What happened
Every package in the family received two new files, setup.mjs and Math_Symbol.js, along with a "preinstall": "node setup.mjs" entry added to each package.json. Anyone who ran npm install against an affected version would have had setup.mjs execute automatically before their install completed.
setup.mjs is a heavily obfuscated dropper. Its only job is to silently download the Bun JavaScript runtime from github[.]com/oven-sh/bun/releases/download/bun-v1.3.13/ and use it to execute the real payload, Math_Symbol.js:
execFileSync(<bun binary>, ['<script_dir>/Math_Symbol.js'], {
stdio: 'inherit',
cwd: <script_dir>
})
The Math_Symbol.js is a heavily obfuscated 728 KB JavaScript file containing credential stealers that harvest secrets from the victim's environment, encrypt the findings, and exfiltrate them to a public GitHub repository whose description reads "Shai-Hulud: Here We Go Again". The payload also contains worm-like propagation functionality to infect packages of other maintainers that have installed one of the compromised packages.
Once again, I ask myself: should we start "shaming" developers who don't use isolation? It still seems I am the exception and most people run their dev environment with full permissions. Why?
I am kind of surprised GitHub doesn't seem to have built a simple classifier for public repos to proactively lock the account of anyone uploading such obviously fishy things (for their own good, at least before the repo is publicly findable), so it can't be used as a rendezvous.
Surely Github's software is good enough that an intern can slop the 80/20 together in a day? It would be an actually good use of AI spending.
> I am kind of surprised GitHub doesn't seem to have built a simple classifier for public repos to proactively lock the account of anyone uploading such obviously fishy things (for their own good, at least before the repo is publicly findable), so it can't be used as a rendezvous.
Maybe that's the idea. Regards, the <insert your favourite 3 letter agency here>
You know with all this AGI swirling around nowadays that is stronger than nation state hackers you think one of these companies would demonstrate just how capable they are by defending public infrastructure.
"Update — August 4, 2026, 13:37 CEST: At least 434 packages (across 1381 versions) have been compromised by the worm, with a combined total of over 2 billion monthly installs at the time of writing."
This is the most boring comment posted on every one of these. NPM is by no means the worst offender here and offers a ton of solutions to this, lots of package managers are behind it or equivalent.
NPM gets targeted a lot because it's popular. That's it.
It’s correct that NPM is not unique but it is the worst for cultural reasons: no other ecosystem started with such a limited language, which lead to the culture of publishing tons of small packages working around things which everything else had builtin. A Python project which has a hundred dependencies is considered quite large but the median React project had north of 30 thousand for years and years.
It’s not that there’s a single stdlib feature which would’ve stopped this but more that JavaScript developers have been conditioned that it’s normal to install tons of packages and update them quite frequently so there are a lot of individual maintainers who if compromised have a surprising impact.
You’re exposed as a function of the number of dependencies so the communities which most normalize many rapidly updating packages are going to be at greater risk. That’s not a simple trade off — that enterprise Java app which updates on a decadal cadence is still worse — but it means you need to accept the risk and use other mitigations.
I just don't think that this is that unique to javascript, it's absolutely not about npm, and I don't think that this is well supported as a relevant feature that leads to these attacks.
Ok, I can agree it is a boring comment, but who is worse?
NPM gets targeted both because it is popular and because there is a wider attack surface (lots of little packages promoted by a huge variety of users) I have a high schooler who published work a couple weeks ago. This is good, but it comes with downsides. Maybe a couple more speed bumps or classifiers would be helpful. Maybe a consolidation of under maintained projects and deprecation is in order.
Arguably crates.io is worse. NPM has cooldowns and has for a while, it has had Trusted Publishing for longer, it has human-approved releases that separate CI/CD from actual publishing. Ruby is probably worse in every way.
Yeah, my point is just that other package managers aren't in a great spot. NPM even lets you separate out "publish" and "release" now where you can publish to the registry but you have to separately "ack" that to release. That's kinda a huge win if people use it.
I just think the framing that npm is so bad is really flatly invalid.
I don’t think npm itself is measurably bad in ways that are useful to index on. Like others, I think that JS as an ecosystem has a culture that encourages both dependency sprawl and living at the edge, both of which contribute to the end problem of OSS malware.
(Rust has a similar culture, to be clear. I don’t think it’s a death knell.)
Other than what happened with 'xz', which was upstream of it getting packaged, how many times has this happened in the debian packages system? Also very popular.
Debian's scale for package distribution is tiny and explicitly curated by maintainers. Everything funnels through Debian. The goals are completely different. Debian packages what's necessary for an OS, npm packages everything needed for any projects arbitrarily. Auditing scales to one of those, not the other.
The quantity of packages that exist at 162150 seems to say to me that there's a great many more than what are "necessary" for the operating system to exist.
sudo apt-cache stats
Total package names: 162150 (5189 k)
Total package structures: 145852 (6417 k)
Normal packages: 69505
Pure virtual packages: 1169
Single virtual packages: 64848
Mixed virtual packages: 355
Missing: 9975
Total distinct source versions: 71172 (1708 k)
Total distinct versions: 71172 (6334 k)
Total distinct descriptions: 139719 (3353 k)
Total dependencies: 435057/121405 (10.6 M)
Total ver/file relations: 73378 (1174 k)
Total Desc/File relations: 142692 (2283 k)
Total Provides mappings: 70533 (1693 k)
Total globbed strings: 268430 (6560 k)
Total slack space: 77.3 k
Total space accounted for: 47.0 M
Total buckets in PkgHashTable: 196613
Unused: 93545
Used: 103068
Utilization: 52.4218%
Average entries: 1.4151
Longest: 19
Shortest: 1
Total buckets in GrpHashTable: 196613
Unused: 86025
Used: 110588
Utilization: 56.2465%
Average entries: 1.46625
Longest: 7
Shortest: 1
162k vs millions. That's not even getting into package update velocity, authorship, the totally divergent goals, etc. I just think it's utterly pointless to compare.
No other package manager is worse than NPM. Outside of its 'popularity', there are several fundamental reasons why this continues to happen to NPM:
- Imported packages are not pinned by default.
- Typescript / Javascript's lack of a standard library encourages the developer to import more packages into their codebase to address the short-comings which increases the risk of importing a bad package.
- Post install scripts execute external code by default upon downloading dependencies.
All of this comes by default in the ecosystem and we continue to see more shai-hulud worms all easily targeting NPM. Not even signed packages are enforced by default either.
What do you mean? The lockfile of all package managers is there for pinning the exact versions. For yarn and pnpm, installs on CI run automatically from lockfile only, for npm I think you still need to run `npm ci` instead of `npm install`. But this guarantees that no new versions get pulled automatically in by CI.
> Typescript / Javascript's lack of a standard library
That's true, but it's not an issue of the package manager / registry
> Post install scripts execute external code by default upon downloading dependencies.
They are disabled by default in all package managers now, the user needs to manually allow them
1. Provenance did not fail, it worked as designed and still shipped malware. The initial 11 packages were published through npm OIDC Trusted Publishing with valid SLSA attestations. The attacker compromised the maintainer's GitHub account and let the projects' own release workflows publish. Provenance proves which commit was built, not that the commit was authorized.
2. There is a booby trap on remediation: the worm installs a watcher that fires an attacker payload when the stolen GitHub token gets revoked. Remove the token monitor first, then rotate.
3. Persistence goes beyond node_modules. It writes .claude/settings.json (SessionStart hook) and .vscode/tasks.json (runOn: folderOpen), each re-executing the dropper. Check repo dotfiles too.
4. No C2 domain to sinkhole: exfil endpoints resolve at runtime from an Ethereum contract. Observed domain is npm-cache.com, but the operator can rotate it and push new code to infected hosts.
If you're auditing: look for setup.mjs, a 727,680 byte Math_Symbol.js (math_init.js in the second wave), and "preinstall": "node setup.mjs" in package.json. Careful, regenerate-unicode-properties ships a legitimate 1 KB Math_Symbol.js; the malicious one is over 700 KB.
Full IOC and package list in the post, updated as the campaign develops.
The cheapest mitigation almost nobody deploys: a version cooldown. These worms get caught fast — this one was flagged same-day, and the article's own timeline shows detection racing ahead of spread. If your CI simply refuses to adopt any version published in the last N days (Renovate supports this natively via minimumReleaseAge), you convert "worm spreads through the ecosystem in hours" into "worm must survive N days of public scrutiny before it can reach you." You give up almost nothing: how often does your product genuinely need a dependency version that's 48 hours old?
Combine that with the workflow split insanitybit describes — build/test jobs holding zero publish credentials, a separate publish job that only touches a finished artifact — and the wormable path is mostly closed without waiting for npm to redesign itself.
None of this is "sufficient" in rcxdude's sense, and that's fine. Sufficiency isn't the bar during an active outbreak; raising the attacker's cost per hop is.
First point.. plus, OTP/MFA authenticated publishing.
This OTP/MFA should come from package repositories, before the package is made publicly available. This is needed so that CD stage is not blocked.
OTP/MFA should be scoped to publishing user/org, not the package. How the OTP/MFA client is managed across the maintainers/org, lies in the scope of maintainers/org.
I think npm can use chatgpt/claude for each published package to detect these types of attack? And if it sees they can restrict the package from making any changes.
aikido.dev: SAST, AI code analysis and therefore a website that uses 100% CPU and prevents scrolling.
To the point of the article: I don't know why GitHub still allows the release feature. It is complete insanity. Tar archives must be constructed manually and checked for leaked keys etc.
I have a suspicion that a lot of these supply chain compromises are done by the security researchers at security vendors, selling software to protect the software supply chain. Spreading fear to create demand for their products.
Like in the good ole days of Windows 98 and antivirus era, a lot of advanced virus techniques in the wild came from the people who used to work for AV companies
> Update — August 4, 2026, 13:37 CEST: At least 868 packages (across 1381 versions) have been compromised by the worm, with a combined total of over 2 billion monthly installs at the time of writing.
This is such lazy or click baiting writing. Who cares how many installations there are per month normally? The high install numbers are almost certainly from running in CI where such secrets don’t exist. How many installs actually occur in a non CI environment and of those how many were the compromised version?
CIs having per-package installs : version ratio > 1 are fundamentally dumb idea in the first place.
In a way, this teaches us that there is something as too much reliability in an ecosystem. Specifically, Github is apparently reliable enough that its occasional outages are insufficient to kill all the companies running these dumb CI setups that redownload packages from the Internet every build - so there's no incentive to reduce waste and improve security globally.
Redownloading and automatically updating to the new version are pretty orthogonal. You can have a solution which caches the packages but would still update to a new version or a solution which redownloads the (verifiably) same package each time. Vendoring libraries stops both but it's the automatic updates which are the biggest risk factor.
At this point, any package adding a pre-install hook where there previously was not one should be denied and treated with extreme suspicion.
It's time pre-install / post-install hooks were killed off. Start with a moratorium on any new ones.
yeah but they can just put the dropper, etc in index.js, so that it runs at import time rather than at install time, no? i guess first-install time is often a privileged developer machine, and will execute in a "server"-like runtime such as Node, Bun, Deno. but blocking preinstall scripts is basic first aid...
Nobody is claiming this is a complete solution to security. I would call this "necessary but not sufficient". You won't get far as an engineer if you refuse to implement "necessary but not sufficient" changes because the change doesn't in and of itself one-shot the entire problem.
These half-measures is why everything has gone to shits. Instead of properly auditing software, reducing the quantity and increasing the quality, we keep pushing more and more garbage where all you find is 2FA that, captcha this, not supported this, app not signed, etc..
Can't agree more. I'm working on OSS security tool that can protect you from Shai-hulud, no half measures.
The idea is to have a local proxy that injects real secrets into requests in-flight, so a compromised library has nothing to steal because it never had access to any of your secrets: https://github.com/inflightsec/agent-vault-proxy
Defense in depth is the “meat and potatoes” of security.
In other words: people should be auditing their software, but we should also design systems and schemes that provide varying degrees of defense and protection when people invariably fail to review the code they run.
Defence in depth is not just 'throw anything in that might improve security' though. The idea is to have multiple strong layers, not a hundred half-measures that are all easily bypassed. A stronger layer might be sandboxing, or separating your build and publishing steps as others have suggested (and also probably worth restricting the credentials the publishing step to just the relevant packages as well). These will at least robustly prevent a malicious dependency from spreading horizontally, but you'll still potentially ship malware to your customers.
I would consider 2FA and signing to be strong layers, when applied well. I think everybody agrees we shouldn’t add layers just for the sake of it.
The fact that it's not sufficient also largely means it's not necessary either, because the real solution is auditing and trusting the codebase as a whole. All you do when disabling install hooks is make a lot of situations much more difficult to handle.
You will also not get very far in engineering if you have a production incident, someone proposes a thing that will mitigate it partially but significantly, and you insist that we can't deploy that mitigation because we need to do the multi-year project that will actually fix it instead. Even if we still need that project, we also need that mitigation.
Sure, solve the problem of "auditing and trusting codebases". Go for it. Shouldn't take you until, oh, let me be generous and give you until next Monday. No sweat.
Feel free to turn it off yourself, just don't be surprised when the attackers switch tactics. And don't make life harder for everyone else by pushing it as mandatory.
(if you want a better mitigation: don't automatically update dependencies in CI. At a minimum have a cooling-off period that you only bypass on manual review. This is not hard to implement and at least gives some time for alarm bells to be sounded before you're pwned. Probably while doing the updates you can also just do a quick sanity check on the changes, that'll also catch the ones using a blatant install hook)
> if you want a better mitigation: don't automatically update dependencies in CI. At a minimum have a cooling-off period that you only bypass on manual review. This is not hard to implement and at least gives some time for alarm bells to be sounded before you're pwned.
One of the problems a lot of companies are having right now is trying to determine a proper window size between CVE release and patching.
On one hand, you have LLM created 0days and attacks are happening almost as fast as CVEs can be posted, and CVEs are being posted at lightning speed. You maybe had a month or a few weeks to patch before, now the window may be down to days or even hours.
On the other hand, you want to prevent these repo bombing attacks.
There's a tension there but I think we're going to end up measuring that window in hours within the year, if we're not already there.
If you need quick responses to such things, you're gonna need some intelligence in the loop regardless, even if it's just deciding when it's worth pushing a new release to prod.
What if it needs to get patched and pushed while you and everyone else in the org are asleep?
I mean that's a big window of time now.
Always has been, arguably. Either way I don't think most people have their CI configured to automatically re-run when a dependency updates (imagine the thundering herd!), the compromises are more incidental to runs happening for other reasons, and that configuration neither guarantees a quick response nor protects against supply chain attacks.
(If you find you do need updates when you're sleeping, you probably need to delegate that process or at least the process of checking the update to someone you trust, and you're probably paying for the service. This blog post is in large part an ad for just such a service).
> You will also not get very far in engineering if
Man, I wish.
Missile defense systems are unnecessary because they could just use tanks
Anti-tank measures are unnecessary because they can just use missiles
What's your solution to using a library without executing the code in it?
The term you are looking for is Defense in Depth/Layers
That makes sense if it's actually a layer. You can create a thousand minor obstacles and it still won't be a very secure system.
"make no mistakes" is not the "real solution"
Neither is 'close the gate with no fence on either side of it'. If you want to run code, you either need to run it in a sandbox or trust it. Choosing to run only part of the code is not really a solution.
(if you want to disable such hooks yourself, then you may get some security by diversity because you're not using the common configuration. But if it becomes the default then these worms will switch to a different vector)
Prod tends to have less privileges than CI/CD. CI/CD tends to be full admin, so it's far more sensitive. Prod tends to have tooling for detecting breaches, better logging, etc. People tend to use containers, which act as a sandbox.
Prod also won't be wormable the way that CI/CD is. With CI/CD I can own another dev, use their creds to push another malicious build script, etc. "Attacker is in my prod env" isn't wormable.
Yes, capabilities in prod would be hugely beneficial but removing CI/CD is massive as a win.
Wouldn't the dropper get executed once tests are run within CI though?
Yes, you should separate "tests execute" into their own unprivileged workflows that don't have "deploy" secrets.
You can also do the same for the build workflow, no?
Yep, I'd recommend it.
yeah, or when a dev starts the local development server (unless that server is containerized).
Dev laptops tend to have better monitoring than CI/CD so I still think this is a better option. You can also have devs use VMs or separate dev environments like an ec2 instance.
To be clear, just solving the CI/CD portion is insufficient, but it is a massive win.
well Deno has the necessary ingredients for defense: file-system permission by path
iirc does pnpm not allow them by default. But even if we killed them off there would still be a chance of the malware hooking into something else or only working in cli applications.
The latest version of all node package managers (npm, yarn, pnpm) now deny this by default. pnpm was ahead of the curve.
npm v12 released last month also defaults into blocking them by default
You'll just end up with people running `./configure` scripts or whatever instead. The solution I've currently landed on is:
1. Audit build scripts/ proc macros for rust code (and mark with cargo-vet).
2. Have an isolated workflow for "build/test/push artifact to temporary place" (s3, github artifact, whatever). No API keys in this workflow.
3. Have another workflow that has the API keys to publish that grabs the artifact and then places it into a registry.
This creates clear separation of "code runs here" and "environment has privileges".
In my own slop-driven programming language I have build scripts declare their capabilities upfront so that you can statically reason about them (same with runtime permissions).
OW. That's gonna leave a mark.
It sucks that we have this glass-jaw dependency system, which is really the main reason these supply chain attacks work.
Really hard to clean up, too. These days, you (being the blackhat) would likely send agents to leverage every compromised repo/app/Web site, almost the instant it comes online, so even if the original mess is cleaned up, there's still a ton of knock-on compromises.
echo "min-release-age=5" >> ~/.npmrc
This should be your default minimum if you work with node.
Updated my docs covering these attacks since 2025:
1. NPM Supply Chain Attack Techniques: https://npm-supply-chain-attack-techniques.pagey.site/
2. NPM Ecosystem Threat Report: https://npm-supply-chain-attacks-25-26.pagey.site/
Does anyone happen to have a grep or similar that helps me check if this is showing up anywhere in the trillions of files in node_modules (or pnpm store)?
The what happened section mentions the addition of the `setup.mjs` and `Math_Symbol.js`, along with a change in `package.json` to add `"preinstall": "node setup.mjs"`, so presumably checking for any of those would be a good indication to check further.
For example:
Crucially, Math_Symbol.js that is almost 800KB, not the innocent 1KB one from regenerate-unicode-properties
when i was searching i got a heartattack when i saw Math_Symbol.js. Thankfully my agent was able to figure it out.
Highly recommend `fd` for the sheer speed:
1. https://github.com/sharkdp/fd2. `brew install fd`
This article has a lot of information and ways to check & clean: https://safedep.io/keyv-npm-supply-chain-compromise/
I ended up asking my agent with auto mode:
can you search all installed node modules for any sign of the shai hulud supply chain attack? What happened Every package in the family received two new files, setup.mjs and Math_Symbol.js, along with a "preinstall": "node setup.mjs" entry added to each package.json. Anyone who ran npm install against an affected version would have had setup.mjs execute automatically before their install completed.
setup.mjs is a heavily obfuscated dropper. Its only job is to silently download the Bun JavaScript runtime from github[.]com/oven-sh/bun/releases/download/bun-v1.3.13/ and use it to execute the real payload, Math_Symbol.js:
execFileSync(<bun binary>, ['<script_dir>/Math_Symbol.js'], { stdio: 'inherit', cwd: <script_dir> }) The Math_Symbol.js is a heavily obfuscated 728 KB JavaScript file containing credential stealers that harvest secrets from the victim's environment, encrypt the findings, and exfiltrate them to a public GitHub repository whose description reads "Shai-Hulud: Here We Go Again". The payload also contains worm-like propagation functionality to infect packages of other maintainers that have installed one of the compromised packages.
find . -type d -name node_modules -prune -exec find {} \( -name setup.mjs -o -name math_init.js -o -name Math_Symbol.js \) \; 2>/dev/null
Once again, I ask myself: should we start "shaming" developers who don't use isolation? It still seems I am the exception and most people run their dev environment with full permissions. Why?
I also wrote an article (https://evertheylen.eu/p/shame-devs-without-isolation/) to flesh out my thoughts, but I'd be really happy to discuss this in the comments.
I am kind of surprised GitHub doesn't seem to have built a simple classifier for public repos to proactively lock the account of anyone uploading such obviously fishy things (for their own good, at least before the repo is publicly findable), so it can't be used as a rendezvous.
Surely Github's software is good enough that an intern can slop the 80/20 together in a day? It would be an actually good use of AI spending.
GitHub announced this a while back:
https://github.blog/changelog/2026-07-28-npm-publish-time-ma...
Ah, I see your problem there
> This requirement will be progressively enforced over time.
"A while back" -- One week ago.
I am curious if they are still implementing the process or if this particular attacker already figured out a way around it.
> I am kind of surprised GitHub doesn't seem to have built a simple classifier for public repos to proactively lock the account of anyone uploading such obviously fishy things (for their own good, at least before the repo is publicly findable), so it can't be used as a rendezvous.
Maybe that's the idea. Regards, the <insert your favourite 3 letter agency here>
You know with all this AGI swirling around nowadays that is stronger than nation state hackers you think one of these companies would demonstrate just how capable they are by defending public infrastructure.
Unless...
Maybe in 6 months.
LLMs are better at attacking than writing secure code.
LLMs aren't terrible at securing systems, humans are bad at using secure systems and typically disable measures with insecure workarounds.
Oh boy, it's a big one.
> Oh boy, it's a big one.
Yup the "Update" in TFA is scary:
"Update — August 4, 2026, 13:37 CEST: At least 434 packages (across 1381 versions) have been compromised by the worm, with a combined total of over 2 billion monthly installs at the time of writing."
Lots of pain ahead.
the irony of the update being at 1337
2,523 and counting
Where is the fbi in this? Why has no one been arrested? This is a massive crime.
I'm guessing (though not sure) the actors are outside the US.
No way to prevent this says only package manager where this regularly happens
This is the most boring comment posted on every one of these. NPM is by no means the worst offender here and offers a ton of solutions to this, lots of package managers are behind it or equivalent.
NPM gets targeted a lot because it's popular. That's it.
It’s correct that NPM is not unique but it is the worst for cultural reasons: no other ecosystem started with such a limited language, which lead to the culture of publishing tons of small packages working around things which everything else had builtin. A Python project which has a hundred dependencies is considered quite large but the median React project had north of 30 thousand for years and years.
I think that's barely meaningful. Which of the compromised packages would have been part of any reasonable stdlib?
It’s not that there’s a single stdlib feature which would’ve stopped this but more that JavaScript developers have been conditioned that it’s normal to install tons of packages and update them quite frequently so there are a lot of individual maintainers who if compromised have a surprising impact.
You’re exposed as a function of the number of dependencies so the communities which most normalize many rapidly updating packages are going to be at greater risk. That’s not a simple trade off — that enterprise Java app which updates on a decadal cadence is still worse — but it means you need to accept the risk and use other mitigations.
I just don't think that this is that unique to javascript, it's absolutely not about npm, and I don't think that this is well supported as a relevant feature that leads to these attacks.
> NPM is by no means the worst offender here
Ok, I can agree it is a boring comment, but who is worse?
NPM gets targeted both because it is popular and because there is a wider attack surface (lots of little packages promoted by a huge variety of users) I have a high schooler who published work a couple weeks ago. This is good, but it comes with downsides. Maybe a couple more speed bumps or classifiers would be helpful. Maybe a consolidation of under maintained projects and deprecation is in order.
Arguably crates.io is worse. NPM has cooldowns and has for a while, it has had Trusted Publishing for longer, it has human-approved releases that separate CI/CD from actual publishing. Ruby is probably worse in every way.
RubyGems actually adopted Trusted Publishing before both npm and crates.io. To my recollection, they were second after PyPI.
(I have no opinion about the overall security posture of these indices.)
No build script control though.
Yep. That remains the norm with Python source distributions as well. It’s a hard thing to overcome when it’s baked deeply into packaging assumptions.
Yeah, my point is just that other package managers aren't in a great spot. NPM even lets you separate out "publish" and "release" now where you can publish to the registry but you have to separately "ack" that to release. That's kinda a huge win if people use it.
I just think the framing that npm is so bad is really flatly invalid.
> the framing that npm is so bad is really flatly invalid.
Is it really though if we're getting thousands of compromised packages regularly?
You can do all the right things and still be legit problematic.
Yes, it has nothing to do with the design of npm (relative to similar languages/ repositories) and everything to do with the popularity.
I don’t think npm itself is measurably bad in ways that are useful to index on. Like others, I think that JS as an ecosystem has a culture that encourages both dependency sprawl and living at the edge, both of which contribute to the end problem of OSS malware.
(Rust has a similar culture, to be clear. I don’t think it’s a death knell.)
Other than what happened with 'xz', which was upstream of it getting packaged, how many times has this happened in the debian packages system? Also very popular.
I don't consider these comparable in any way that's worthwhile. The scale and goals are completely different.
How are they not comparable?
Debian's scale for package distribution is tiny and explicitly curated by maintainers. Everything funnels through Debian. The goals are completely different. Debian packages what's necessary for an OS, npm packages everything needed for any projects arbitrarily. Auditing scales to one of those, not the other.
The quantity of packages that exist at 162150 seems to say to me that there's a great many more than what are "necessary" for the operating system to exist.
sudo apt-cache stats
Total package names: 162150 (5189 k) Total package structures: 145852 (6417 k) Normal packages: 69505 Pure virtual packages: 1169 Single virtual packages: 64848 Mixed virtual packages: 355 Missing: 9975 Total distinct source versions: 71172 (1708 k) Total distinct versions: 71172 (6334 k) Total distinct descriptions: 139719 (3353 k) Total dependencies: 435057/121405 (10.6 M) Total ver/file relations: 73378 (1174 k) Total Desc/File relations: 142692 (2283 k) Total Provides mappings: 70533 (1693 k) Total globbed strings: 268430 (6560 k) Total slack space: 77.3 k Total space accounted for: 47.0 M Total buckets in PkgHashTable: 196613 Unused: 93545 Used: 103068 Utilization: 52.4218% Average entries: 1.4151 Longest: 19 Shortest: 1 Total buckets in GrpHashTable: 196613 Unused: 86025 Used: 110588 Utilization: 56.2465% Average entries: 1.46625 Longest: 7 Shortest: 1
162k vs millions. That's not even getting into package update velocity, authorship, the totally divergent goals, etc. I just think it's utterly pointless to compare.
left-pad was over a decade ago. it's a problem with the registry itself, more than just the package manager.
left-pad is totally irrelevant to this conversation.
No other package manager is worse than NPM. Outside of its 'popularity', there are several fundamental reasons why this continues to happen to NPM:
- Imported packages are not pinned by default.
- Typescript / Javascript's lack of a standard library encourages the developer to import more packages into their codebase to address the short-comings which increases the risk of importing a bad package.
- Post install scripts execute external code by default upon downloading dependencies.
All of this comes by default in the ecosystem and we continue to see more shai-hulud worms all easily targeting NPM. Not even signed packages are enforced by default either.
> Imported packages are not pinned by default
What do you mean? The lockfile of all package managers is there for pinning the exact versions. For yarn and pnpm, installs on CI run automatically from lockfile only, for npm I think you still need to run `npm ci` instead of `npm install`. But this guarantees that no new versions get pulled automatically in by CI.
> Typescript / Javascript's lack of a standard library
That's true, but it's not an issue of the package manager / registry
> Post install scripts execute external code by default upon downloading dependencies.
They are disabled by default in all package managers now, the user needs to manually allow them
Two out of three of your points - the first and last - are just incorrect.
Ruby is worse. crates.io is arguably worse.
echo "min-release-age=5" >> ~/.npmrc
I mean what are these devs doing that they are day-1 updating npm packages still?
How many instances of this are required before npm package maintainers learn?
ad slop post
We (StepSecurity) published a full analysis of both payload stages: https://www.stepsecurity.io/blog/chaindrop-npm-worm
Some additional detail from our analysis:
1. Provenance did not fail, it worked as designed and still shipped malware. The initial 11 packages were published through npm OIDC Trusted Publishing with valid SLSA attestations. The attacker compromised the maintainer's GitHub account and let the projects' own release workflows publish. Provenance proves which commit was built, not that the commit was authorized.
2. There is a booby trap on remediation: the worm installs a watcher that fires an attacker payload when the stolen GitHub token gets revoked. Remove the token monitor first, then rotate.
3. Persistence goes beyond node_modules. It writes .claude/settings.json (SessionStart hook) and .vscode/tasks.json (runOn: folderOpen), each re-executing the dropper. Check repo dotfiles too.
4. No C2 domain to sinkhole: exfil endpoints resolve at runtime from an Ethereum contract. Observed domain is npm-cache.com, but the operator can rotate it and push new code to infected hosts.
If you're auditing: look for setup.mjs, a 727,680 byte Math_Symbol.js (math_init.js in the second wave), and "preinstall": "node setup.mjs" in package.json. Careful, regenerate-unicode-properties ships a legitimate 1 KB Math_Symbol.js; the malicious one is over 700 KB.
Full IOC and package list in the post, updated as the campaign develops.
ai slop comment. post the original prompt
The cheapest mitigation almost nobody deploys: a version cooldown. These worms get caught fast — this one was flagged same-day, and the article's own timeline shows detection racing ahead of spread. If your CI simply refuses to adopt any version published in the last N days (Renovate supports this natively via minimumReleaseAge), you convert "worm spreads through the ecosystem in hours" into "worm must survive N days of public scrutiny before it can reach you." You give up almost nothing: how often does your product genuinely need a dependency version that's 48 hours old?
Combine that with the workflow split insanitybit describes — build/test jobs holding zero publish credentials, a separate publish job that only touches a finished artifact — and the wormable path is mostly closed without waiting for npm to redesign itself.
None of this is "sufficient" in rcxdude's sense, and that's fine. Sufficiency isn't the bar during an active outbreak; raising the attacker's cost per hop is.
First point.. plus, OTP/MFA authenticated publishing.
This OTP/MFA should come from package repositories, before the package is made publicly available. This is needed so that CD stage is not blocked.
OTP/MFA should be scoped to publishing user/org, not the package. How the OTP/MFA client is managed across the maintainers/org, lies in the scope of maintainers/org.
This still does nothing to prevent anyone from publishing a bad package, for example a compromised device/dev in the organization.
A cooldown of a day, and maybe not updating on weekends will save you from that.
It's time to stop moving at the speed of stupid.
I think npm can use chatgpt/claude for each published package to detect these types of attack? And if it sees they can restrict the package from making any changes.
the remedy is worse than the disease
aikido.dev: SAST, AI code analysis and therefore a website that uses 100% CPU and prevents scrolling.
To the point of the article: I don't know why GitHub still allows the release feature. It is complete insanity. Tar archives must be constructed manually and checked for leaked keys etc.
I got the news via https://safedep.io/keyv-npm-supply-chain-compromise/
I have a suspicion that a lot of these supply chain compromises are done by the security researchers at security vendors, selling software to protect the software supply chain. Spreading fear to create demand for their products.
Like in the good ole days of Windows 98 and antivirus era, a lot of advanced virus techniques in the wild came from the people who used to work for AV companies
That would be extremely surprising, given the number and severity of federal crimes involved.
(I also dare say: many of these attackers demonstrate a better in-depth understanding of packaging ecosystems than supply chain security vendors do.)
the federal crimes part is irrelevant if its below the threshold of federal authorities actually cracking down on them and figuring out entire chain.
just because credit card theft and other types of scam are illegal
I remember how ddos attackers created "DDOS protection" companies to protect their victims against DDOS.
I don’t think the impact of these recent malware campaigns is below the threshold for federal interest.
> Update — August 4, 2026, 13:37 CEST: At least 868 packages (across 1381 versions) have been compromised by the worm, with a combined total of over 2 billion monthly installs at the time of writing.
This is such lazy or click baiting writing. Who cares how many installations there are per month normally? The high install numbers are almost certainly from running in CI where such secrets don’t exist. How many installs actually occur in a non CI environment and of those how many were the compromised version?
> almost certainly from running in CI where such secrets don’t exist.
CI usually has the most privileged secrets anywhere in a company lol
CIs having per-package installs : version ratio > 1 are fundamentally dumb idea in the first place.
In a way, this teaches us that there is something as too much reliability in an ecosystem. Specifically, Github is apparently reliable enough that its occasional outages are insufficient to kill all the companies running these dumb CI setups that redownload packages from the Internet every build - so there's no incentive to reduce waste and improve security globally.
Redownloading and automatically updating to the new version are pretty orthogonal. You can have a solution which caches the packages but would still update to a new version or a solution which redownloads the (verifiably) same package each time. Vendoring libraries stops both but it's the automatic updates which are the biggest risk factor.