Tj-actions/changed-files GitHub Action Compromised – used by over 23K repos

https://www.stepsecurity.io/blog/harden-runner-detection-tj-actions-changed-files-action-is-compromised

273 298 1 year ago

What Happened? • The compromised Action executes a Python script that dumps CI/CD secrets from the Runner Worker process. • Multiple v35 tags were modified four hours ago, indicating a recent supply chain attack. • The malicious behavior can be observed in StepSecurity Harden-Runner insights, showing the Action downloading and executing an unauthorized script.

varunsharma076• 1 year ago

https://github.com/tj-actions/changed-files/issues/2463

jasonthorsness3• 1 year ago

Wow that's scary, they updated tons of tags to an offending random commit. With the way repositories are included in automation and the fact that this adjusted the tags of older versions (so not requiring an upgrade) this sort of attack can have a huge impact very quickly :(.

Maybe GitHub should have some kind of security setting a repo owner can make that locks-down things like old tags so after a certain time they can't be changed.

SAI_Peregrinus2• 1 year ago

Tags are a git concept, not a GitHub concept. Tags provide human-readable names to commits. They're intended to be changeable, to allow things like a "latest" tag pointing to the latest release. Tags aren't versions, commit hashes are.

kurmiashish4• 1 year ago

Disclaimer: I am a co-founder of StepSecurity.

StepSecurity Harden-Runner detected this security incident by continuously monitoring outbound network calls from GitHub Actions workflows and generating a baseline of expected behaviors. When the compromised tj-actions/changed-files Action was executed, Harden-Runner flagged it due to an unexpected endpoint appearing in the network traffic—an anomaly that deviated from the established baseline. You can checkout the project here: https://github.com/step-security/harden-runner

shawabawa3• 1 year ago

A simpler method to detect this would be to store GitHub action tag hashes and freeze an action if any tag is changed

cyrnel2• 1 year ago

The advertising in this article is making it actively difficult to figure out how to remediate this issue. The "recovery steps" section just says "start our 14 day free trial".

The security industry tolerates self-promotion only to the extent that the threat research benefits everyone.

kurmiashish4• 1 year ago

Thank you, cyrnel, for the feedback! We are trying our best to help serve the community. Now, we have separate recovery steps for general users and our enterprise customers.

mubou5• 1 year ago

In recent years, it's started to feel like you can't trust third-party dependencies and extensions at all anymore. I no longer install npm packages that have more than a few transitive dependencies, and I've started to refrain from installing vscode or chrome extensions altogether.

Time and time again, they either get hijacked and malicious code added, or the dev themselves suddenly decides to betray everyone's trust and inject malicious code (see: Moq), or they sell out to some company that changes the license to one where you have to pay hundreds of dollars to keep using it (e.g. the recent FluentAssertions debacle), or one of those happens to any of the packages' hundreds of dependencies.

Just take a look at eslint's dependency tree: https://npmgraph.js.org/?q=eslint

Can you really say you trust all of these?

scrapcode• 1 year ago

Are there examples of these types of actions in other circles outside of the .NET ecosystem? I knew about the FluentAssertions ordeal, but the Moq thing was news to me. I guess I've just missed it all.

do_not_redeem• 1 year ago

node-ipc is a recent example from the Node ecosystem. The author released an update with some code that made a request to a geolocation webservice to decide whether to wipe the local filesystem.

sanex• 1 year ago

Missed them too. Always was annoyed by FluentAssertions anyway, some contractor added it to a project that we took over couldn't see the value add.

mh-• 1 year ago

eslint's dependency tree

And if you turn on devDependencies (top right), it goes from 85 to 1263.

Terr_3• 1 year ago

I'd also emphasize out that there's nothing safe about it being "only dev", given how many attacks use employee computers (non-prod) as a springboard elsewhere.

XorNot• 1 year ago

The original .NET (and I think Java?) had an idea in them of basically library level capability permissions.

That sort of idea seems increasingly like what we need because reputation based systems can be gamed too easily: i.e. there's no reason an action like this ever needed network access.

mdaniel3• 1 year ago

It was only recently removed in Java and there was a related concept (adopted from OSGi) designed to only export certain symbols -- not for security but for managing the surface area that a library vendor had to support

But I mentioned both of those things because [IMHO] they both fell prey to the same "humanity bug": specifying permissions for anything (source code, cloud security, databases, Kubernetes, ...) is a lot of trial and error, whereas {Effect: Allow, Action: ["*:*"]} always works and so they just drop a "TODO: tighten permissions" and go on to the next Jira

I had high hopes for the AWS feature "Make me an IAM Policy based on actual CloudTrail events" but it talks a bigger game than it walks

kilroy123• 1 year ago

I agree completely.

If I see a useful extension, I want to use is on GitHub. I fork it. Sometimes I make a bookmarklet with the code instead.

I keep most extensions off until I need to use them. Then, I enable them, use them, and turn them off again. I try to even keep Mac apps to a minimum.

ocdtrekkie• 1 year ago

When using NuGet packages I usually won't even consider ones with non-Microsoft dependencies, and I like to avoid third-party dependencies altogether. I used to feel like this made me a weird conspiracy theorist but it's holding up well!

It also has led to some bad but fun choices, like implementing POP3 and IMAP directly in my code, neither of which worked well but taught me a lot?

usef-• 1 year ago

Yes. Same with browser plugins. I've heard multiple free-plugin authors say they're receiving regular offers to purchase their projects. I'm sure some must take up the offer.

ronjouch6• 1 year ago

For an example of a scary list of such offers, see https://github.com/extesy/hoverzoom/discussions/670

Gigachad• 1 year ago

I have long since stopped using any extension that doesn’t belong to an actual company (password managers for example). Even if they aren’t malware when you installed them, they will be after they get sold.

from-nibly3• 1 year ago

I got an outreach for an extension I made as a joke. It had like maybe 5000 downloads ever.

fumufumu• 1 year ago

Did you turn off updates on your phone as well? Because 99.999% of people have app auto-updates and every update could include an exploit.

I'm not saying you're wrong not to trust package managers and extensions but you're life is likely full of the same thing. The majority of apps are made from 3rd party libraries which are made of 3rd party libraries, etc.... At least on phones they update constantly, and every update is a chance to install more exploits.

The same is true for any devices that get updates like a Smart TV, router, printer, etc.... I mostly trust Apple, Microsoft, and Google to check their 3rd party dependencies, (mostly), but don't trust any other company - and yet I can't worry about it. Don't update and I don't get security vulnerabilities fixed. Do update and I take the chance that this latest update has a 3rd party exploit buried in a 3rd party library.

xign3• 1 year ago

I don't trust apps. I trust Apple (enough) that they engineered iOS to have a secure enough sandbox that a random calculator app can't just compromise my phone.

Most developer packages have much higher permission levels because they integrate it with your code without a clear separation of boundaries. This is why attackers now like to attack GitHub Actions because if you get access to secrets you can do a lot of damage.

throwaway48476• 1 year ago

The solution for trusting dependencies is signed public builds and ML 'weirdness' detectors that require manual review.

bolognafairy• 1 year ago

If this were “the solution”, then the many, many smart individuals and teams tasked with solving these problems throughout the software industry would’ve been out of work for some time now.

It’s obviously more complicated than that.

Signed public builds don’t inherently mean jack. It highly depends on the underlying trust model.

—

Malicious actor: “we want to buy your browser extension, and your signing credentials”.

Plugin author: “Well, OK”.

—

Malicious actor: hijacks npm package and signs new release with new credentials

The vast majority of dependent project authors: at best, see a “new releaser” warning from their tooling, which is far from unusual for many dependencies. ignores After all, what are they going to do?.

—

Hacker News, as usual, loves to pretend it has all the answers to life’s problems, and the issue is that nobody has listened to them.

ashishb2• 1 year ago

Can you really say you trust all of these?

We need better capabilities. E.g. when I run `fd`, `rg` or similar such tool, why should it have Internet access?

IMHO, just eliminating Internet access for all tools (e.g. in a power mode), might fix this.

The second problem is that we have merged CI and CD. The production/release tokens should ideally not be on the same system as the ones doing regular CI. More users need access to CI (especially in the public case) than CD. For example, a similar one from a few months back https://blog.yossarian.net/2024/12/06/zizmor-ultralytics-inj...

CamJN• 1 year ago

You also need to block write access, so they can’t encrypt all your files with an embedded public key. And read access so they can’t use a timing side channel to read a sensitive file and pass that info to another process with internet privileges to report the secret info back to the bad guy. You get the picture, I’m sure.

redserk2• 1 year ago

I’ve been doing all of my dev work in a virtual machine as a way to clamp things down. I’ve even started using a browser in a VM as a primary browser.

Computers are fast enough where the overhead doesn’t feel like it’s there for what I do.

For development, I think Vagrant should make a comeback as one of the first things to setup in a repo/group of repos.

hypeatei2• 1 year ago

OpenBSDs pledge[0] system call is aimed at helping with this. Although, it's more of a defense-in-depth measure on the maintainers part and not the user.

The pledge() system call forces the current process into a restricted-service operating mode. A few subsets are available, roughly described as computation, memory management, read-write operations on file descriptors, opening of files, networking (and notably separate, DNS resolution). In general, these modes were selected by studying the operation of many programs using libc and other such interfaces, and setting promises or execpromises.

[0] https://man.openbsd.org/pledge.2

h4ck_th3_pl4n3t2• 1 year ago

But that's what firejail and docker/podman are for. I never run any build pipeline on my host system, and neither should you. Build containers are pretty good for these kind of mitigations of security risks.

mnahkies• 1 year ago

I've found firejail to be a useful tool for this (https://github.com/netblue30/firejail), and additionally use opensnitch (https://github.com/evilsocket/opensnitch) to monitor for unexpected network requests.

For CI/CD using something like ArgoCD let's you avoid giving CI direct access to prod - it still needs write access to a git repo, and ideally some read access to Argo to check if deployment succeeded but it limits the surface area.

mschuster91• 1 year ago

We need better capabilities.

I'd love to say "just use Kubernetes and run Nexus as a service inside" but unfortunately Network Policies are seriously limited [1]...

[1] https://kubernetes.io/docs/concepts/services-networking/netw...

nextaccountic• 1 year ago

We need better capabilities. E.g. when I run `fd`, `rg` or similar such tool, why should it have Internet access?

Yeah!! We really need to auto sandbox everything by default, like mobile OSes. Or the web.

People browse the web (well, except Richard Stallman) all the time, and run tons of wildly untrusted code, many of them malicious. And apart from zero days here and there, people don't pay much attention to it, and will happily enter any random website in the same machine they also store sensitive data.

At the same time, when I open a random project from Github on VSCode, it asks whether the project is "trusted". If not, it doesn't run the majority of features like LSP server. And why not? Because the OS doesn't sandbox stuff by default. It's maddening.

ptx• 1 year ago

FreeBSD has Capsicum [0] for this. Once a process enters capability mode, it can't do anything except by using already opened file descriptors. It can't spawn subprocesses, connect to the network, load kernel modules or anything else.

To help with things that can't be done in the sandbox, e.g. DNS lookups and opening new files, it provides the libcasper library which implements them using helper processes.

Not all utilities are sandboxed, but some are and hopefully more will be.

Linux recently added Landlock [1] which seems sort of similar, although it has rulesets and doesn't seem to block everything by default, as far as I can tell from quickly skimming the docs.

[0] https://wiki.freebsd.org/Capsicum

[1] https://docs.kernel.org/userspace-api/landlock.html

kubectl_h• 1 year ago

npm supply chain attacks are the lone thing that keeps me up at night, so to speak. I shudder thinking about the attack surface.

I go out of my way to advocate for removing dependencies and pushing against small dependency introductions in a large ruby codebase. Some dependencies that suck and impose all sorts of costs, from funky ass idiosyncratic behavior or absurd file sizes (looking at you any google produced ruby library, especially the protocol buffer dependent libraries) are unavoidable, but I try to keep fellow engineers honest about introducing libraries that do things like determine the underlying os or whatever and push towards them just figuring that out themselves or, at the least, taking "inspiration" from the code in those libraries and reproducing behavior.

A nice side effect of AI agents and copilots is they can sometimes write "organic" code that does the same thing as third party libraries. Whether that's ethical, I don't know, but it works for me.

harrisi5• 1 year ago

This isn't new - Thompson warned us 40 years ago (and I believe others before him) in his Reflections on Trusting Trust paper.

It's something I've been thinking about lately because I was diving into a lot of discussion from the early 90s regarding safe execution of (what was, at the time, called) "mobile code" - code that a possibly untrustworthy client would send to have executed on a remote server.

There's actually a lot of discussion still available from w3 thankfully, even though most of the papers are filled with references to dead links from various companies and universities.

It's weirdly something that a lot of smart people seemed to have thought about at the start of the World Wide Web which just fell off. Deno's permissions are the most interesting modern implementation of some of the ideas, but I think it still falls flat a bit. There's always the problem of "click yes to accept the terms" fatigue as well, especially when working in web development. It's quite reasonable for many packages one interacts with in web development to need network access, for example, so it's easy to imagine someone just saying "yup, makes sense" when a web-related package requests network access.

Also none of this even touches on the reality of so much code which exists to brutally impact a business need (or perceived need). Try telling your boss you need a week or two to audit every one of the thousands of packages for the report generator app.

imoreno3• 1 year ago

Trusting Trust is not about this at all. It's about the compiler being compromised, and making it impossible to catch malicious code by inspecting the source code.

The problem here is that people don't even bother to check the source code and run it blindly.

nextts4• 1 year ago

If you want a Cathedral they still exist. Use .NET and only MS Nuget packages.

stickfigure• 1 year ago

I'm just going to say this out loud: It's mostly a Javascript thing.

Not that every other platform in the world isn't theoretically vulnerable to the same sort of attack, but there's some deep-rooted culture in the javascript community that makes it especially vulnerable.

The charitable interpretation is "javascript evolves so fast!". The uncharitable interpretation is "they are still figuring it out!"

Either way, I deliberately keep my javascript on the client side.

puffybuf• 1 year ago

Stealing crypto is so lucrative. So there is a huge 'market' for this stuff now that wasn't there before. Security is more important now than ever. I started sandboxing Emacs and python because I can't trust all the packages.

semi-extrinsic• 1 year ago

What do you use for sandboxing?

ycombiredd• 1 year ago

Yes, this...

I hope the irony is not completely lost on the fine folks at semgrep that the admittedly "overkill" suggested semgrep solution is exactly the type of pattern that leads to this sort of vulnerability: that of executing arbitrary code that is modifiable completely outside of one's own control.

re-thc• 1 year ago

In recent years, it's started to feel like you can't trust third-party dependencies and extensions at all anymore.

Was it really a recent thing?

Just take a look at eslint's dependency tree

Npm / node has always been extra problematic though. Where's the governance / validation on these packages? It's free for all.

h4ck_th3_pl4n3t2• 1 year ago

The alternative would be to find a sustainable funding model for open source, which is the source of betrayals due to almost all of the maintainers having to sell their projects to make a living in the first place.

The problem you're describing is an economical and a social one.

Currently, companies exploit maintainers of open source projects. There are rarely projects that make it due to their popularity, like webpack, when it comes to funding...but the actual state is that everyone that webpack is based on as a dependency didn't get a single buck for it, which is unfair, don't you think?

On top of sustainable funding, we need to change our workflows to reproducible build ecosystems that can also revert independent of git repositories. GitHub has become the almost single source of code for the planet, which is insane to even bet on from a risk assessment standpoint. But it's almost impossible to maintain your own registry or mirror of code in most ecosystems due to the sheer amount of transitive dependencies.

Take go mod vendor, for example. It's great to stick your dependencies but it comes with a lot of overhead work in case something like OPs scenario happens to its supply chain. And we need to account for that in our workflows.

from-nibly3• 1 year ago

It's not going to happen. If buying a forever license of unlimited usage for an open source library cost $1 I'd skip it. Not be cause I don't want to give money to people who deserve it, but because of the absolute monstrous bureaucratic nightmare that comes from trying to purchase anything at a company larger than 10 people.

Don't even talk about when the company gets a lawyer who knows what a software license is.

prepend2• 1 year ago

Open source has a very sustainable funding model as evidenced by 50 years of continuous, quality software being developed and maintained by a diverse set of maintainers.

I say sustainable because it has been sustained, is increasing in quantity and quality, and reasonably seems to be continuing.

companies exploit maintainers of open source projects Me giving something away and others taking what I give is not exploitation. Please don’t speak for others and claim people are exploited. One of the main tenets of gnu is to prevent exploitation.

from-nibly3• 1 year ago

This is the death of fun. Like when you had to use SSL for buying things online.

Adding SSL was not bad, don't get me wrong. It's good that it's the default now. However. At one point it was sorta risky, and then it became required.

Like when your city becomes crime ridden enough that you have to lock your car when you go into the grocery store. Yeah you probably should have been locking it the whole time. what would it have really cost? But now you have to, because if you don't your car gets jacked. And that's not a great feeling.

aorloff• 1 year ago

Just you wait. Here in America when your city becomes crime ridden enough you start leaving it unlocked again.

asveikau2• 1 year ago

In the era of the key fob it's pretty automatic to lock the car every time. Some cars even literally do it for you. I hardly think of this, let alone get not great feelings about it.

sroussey• 1 year ago

Yeah, I’m working on a library where the core is dependency free. It takes longer but I know the provenance of everything—me!

jrockway• 1 year ago

You can trust (in time), but you can't blindly upgrade. Vendor or choose to "lock" with a cryptographic hash over the files your build depends on. You then need to rebuild that trust when you upgrade (wait until everyone else does; read the diffs yourself).

There is something to be said for the Go proverb "a little copying is better than a little dependency", as well. If you want a simple function from a complicated library, you can probably copy it into your own codebase.

ronjouch6• 1 year ago

the Go proverb "a little copying is better than a little dependency"

What a nice way to put it! Thanks for the mention and thanks for making me discover https://go-proverbs.github.io/ .

phantomathkg2• 1 year ago

How far will you go? If you are user of Linux, are you going to inspect all sources before using a distribution?

padjo• 1 year ago

Years ago I saw that most browser extensions ask for the permission “can access all data on all websites” and thought yeah let’s not do that…

bobnamob• 1 year ago

Yeah, I’ve moved off vscode entirely, back to fully featured out of the box ides for me. Jetbrains make some excellent tools and I don’t need to install 25 (dubious) plugins for them to be excellent

ta1243• 1 year ago

This amuses me:

But Lewis Ardern on our team wrote a Semgrep rule to find usages of tj-actions, which you can run locally (without sending code to the cloud) via: semgrep --config r/10Uz5qo/semgrep.tj-actions-compromised.

So "remote code you download from a repo automatically and run locally has been compromised, here run this remote code you download from a repo automatically and run locally to find it"

aryx• 1 year ago

A semgrep rule is not code; it does not run anything.

ozim• 1 year ago

You should never have trusted blindly in third-party dependencies in the first place.

Abnormal behavior was to trust by default.

lenkite• 1 year ago

This is why I have begin to prefer languages with comprehensive, batteries-included standard libraries so that you need very few dependencies. Dep Management has become a full time headache nowadays with significant effort going into CVE analysis.

mlfreeman• 1 year ago

I think this is the root of the problem.

I think library/runtime makers aren't saying "let's make an official/blessed take on this thing that a large number of users are doing" as much as they should.

Popular libraries for a given runtime/language should be funded/bought/cloned by the runtime makers (e.g. MS for .NET, IBM/Oracle for Java) more than they are now.

I know someone will inevitably mention concerns about monopolies/anti-trust/"stifling innovation" but I don't really care. Sometimes you have to standardize some things to unlock new opportunities.

imoreno3• 1 year ago

Instead of bloating the base language for this, a trusted entity could simply fork those libraries, vet them, and repackage into some "blessed lib" that people like you can use in peace. In fact, the level of trust needed to develop safe libraries is less than developing language features.

icetank• 1 year ago

49 modules with only one maintainer and over 600 modules with only one maintainer if devDependencies are included. This is only a matter of time until the next module becomes compromised.

touristtam• 1 year ago

I have used https://github.com/lirantal/npq for a good while now, but I am yearning for that'd look deeper into the health of the package at hand.

YZF• 1 year ago

You should have never trusted them. That ecosystem is fine for hobbyists but for professional usage you can't just grab something random from the Internet and assume it's fine. Security or quality wise.

abhisek• 1 year ago

I think the conventional approach of checking for vulnerabilities in 3rd party dependencies by querying CVE or some other database has set the current behaviour i.e. if its not vulnerable it must be safe. This implicit trust on vulnerability databases has been exploited in the wild to push malicious code to downstream users.

I think we will see security tools shifting towards "code" as the source of truth when making safety and security decision about 3rd party packages instead of relying only on known vulnerability databases.

Take a look at vet, we are working on active code analysis of OSS packages (+ transitive dependencies) to look for malicious code: https://github.com/safedep/vet

dan_manges• 1 year ago

GitHub Actions should use a lockfile for dependencies. Without it, compromised Actions propagate instantly. While it'd still be an issue even with locking, it would slow down the rollout and reduce the impact.

Semver notation rather than branches or tags is a great solution to this problem. Specify the version that want, let the package manager resolve it, and then periodically update all of your packages. It would also improve build stability.

jasonthorsness3• 1 year ago

Since they edited old tags here … maybe GitHub should have some kind of security setting a repo owner can make that locks-down things like old tags so after a certain time they can't be changed.

CaliforniaKarl• 1 year ago

In your GitHub Actions YAML, instead of referencing a specific tag, you can reference a specific commit. So, instead of …

    uses: actions/checkout@v4

… you can use …

    uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683

mceachen2• 1 year ago

GitHub actions supports version numbers, version ranges, and even commit hashes.

frenchtoast85• 1 year ago

The version numbers aren't immutable, so an attacker can just update the versions to point to the compromised code, which is what happened here. Commit hashes are a great idea, but you still need to be careful: lots of people use bots like Renovate to update your pinned hashes whenever a new version is published, which runs into the same problem.

werrett6• 1 year ago

Only commit hashes are safe. In this case the bad actor changed all of the version tags to point to their malicious commit. See https://github.com/tj-actions/changed-files/tags

All the tags point to commit `^0e58ed8` https://github.com/tj-actions/changed-files/commit/0e58ed867...

eddythompson80• 1 year ago

You can always just fork it and reference your own fork.

postalrat• 1 year ago

Or just write your own.

cmckn• 1 year ago

I always use commit hashes for action versions. Dependabot handles it, it’s a no brainer.

Terr_3• 1 year ago

commit hashes

There is some latent concern that most git installations use SHA-1 hashes, as opposed to SHA-256. [0]

Also the trick of creating a branch that happens to be named the same as a revision, which then takes precedence for certain commands.

[0] https://git-scm.com/docs/hash-function-transition

mixologic2• 1 year ago

All the version tags got relabled to point to a compromised hash. Semver does nothing to help with this.

your build should always use hashes and not version tags of GHA's

nextts4• 1 year ago

Also don't het GH actions to do anything other than build and upload artifacts somewhere. Ideally a write only role. Network level security too no open internet.

Use a seperate system for deployments. That system must be hygienic.

This isn't foolproof but would make secrets dumping not too useful. Obviously an attack could still inject crap into your artefact. But you have more time and they need to target you. A general purpose exploit probably won't hurt as much.

jasonthorsness3• 1 year ago

I think this article from earlier today was the discoverer who opened the issue

https://news.ycombinator.com/item?id=43367987

simonw• 1 year ago

I've always felt uncomfortable adding other people's actions to my GitHub workflows, and this is exactly the kind of thing I was worried about.

I tend to stick to the official GitHub ones (actions/setup-python etc) plus the https://github.com/pypa/gh-action-pypi-publish one because I trust the maintainers to have good security habits.

3eb7988a1663• 1 year ago

That's exactly where I stand, and I feel partially vindicated by this outcome. There are so many useful Github actions made by randos, but I am not adding more unvetted dependencies to my project. I will unhappily copy and paste some useful code into my project rather than relying upon yet another mutable dependency.

mirashii• 1 year ago

Not the first time this particular action has had a vulnerability, either.

https://nvd.nist.gov/vuln/detail/CVE-2023-51664

zahlman2• 1 year ago

I could have sworn that I've seen other GitHub Actions vulnerabilities that worked the same way, too. And/or HN submissions talking about this specific kind of vulnerability, the standard mitigation strategies, etc.

Feels like the same kind of problem as SQL injection, where everybody kinda knows about it and some people are actively aware and there are standard ways to avoid it but it still happens all the time anyway.

Might also be a good time to mention I'm really not a fan of YAML.

tsujamin• 1 year ago

How does SBOM and such account for this? If you’re a package maintainer, do you need to include CI pipeline plugins, their dependencies, going down as far as the pipeline host, in your security-relevant dependencies? Hard problems :/

captn3m04• 1 year ago

Most recommendations treat SBOM as the “ingredients” and are he build dependencies such as GitHub Actions as the recipe.

However, I think the GitHub SBOM features include GitHub Actions as dependencies, but that is merely a side-effect of their Dependabot heritage.

neuroelectron• 1 year ago

CI was sold as a solution for engineers having too much sovereignty. So that's what they got.

random17• 1 year ago

I wish Github required some sort of immutability for actions by default as most package managers do, either by requiring reusable actions to be specified via commit hash or by preventing the code for a published tag to be changed.

At the moment the convention is to only specify the tag, which is not only a security issue as we see here, but may also cause workflows to break if an action author updates the action.

wutwutwat3• 1 year ago

You can target `some/action@commithash` already, that's up to you. You're also free to fork or clone each action you use, vet the code, and consume your fork in your workflows. You can also disable the use of third party actions at an org level, or approve them on a case-by-case basis.

This all depends on your threat model and risk tolerance, it's not so much a GitHub problem. There will always be bad code that exists, especially on the largest open source code hosting platform. You defend against it because that's more realistic than trying to eradicate it.

arianvanp• 1 year ago

One problem with this is that actions can be Composite and call arbitrary other actions. So only if you use actions that themselves lock everything by commit for the actions they depend on you're safe.

chuckadams2• 1 year ago

Someone elsewhere suggested a lockfile, which seems a pretty obvious solution in hindsight. I'm fine with commit hashes, but the UX is terrible and consists of pasting the action into into StepSecurity's thingie, when this is something that GH should have built in.

mubou5• 1 year ago

Someone else in the thread mentioned that this is coming! https://github.com/features/preview/immutable-actions

xyst2• 1 year ago

A company I worked at went all in on GH too. The internal gh team probably going to do a fire drill this whole weekend and app teams forced to rotate all secrets and credentials.

Fortunately don’t have to deal with that shit anymore

frenchtoast85• 1 year ago

My day job is also in the middle of moving everything to Github Actions, so this is fun. But in my case, we aren't affected by this vulnerability because it could only be exploited by workflows with public logs, and currently my company only uses Github Actions for private repositories.

werrett6• 1 year ago

I mean maybe! But only if you've removed all of the usage of this compromised `tj-actions/changedfiles` action, across all your repos and their branches.

Otherwise, if you continue to use it and it will run anytime there has been a push. Potentially on any branch, not just `main`! Depending on your GH config.

Unless you've blocked `tj-actions/changed-files` you're banking on the bad actor not coming back tonight and making malicious commit that exfils those secrets to pastebin.com.

arionmiles• 1 year ago

It's possible to whitelist actions on an org level.

You can whitelist

- all actions from a specific org (e.g. actions/*)

- a specific action (e.g. actions/setup-go)

- a specific version of a specific action (e.g. actions/setup-go@commit-sha)

Any workflow attempting to use actions outside of the whitelist will simply fail to start up.

dboreham• 1 year ago

Good policy to fork all actions not owned by a reputable organization (e.g. github themselves).

frenchtoast85• 1 year ago

You can combine this with a policy that blocks third party actions from being used across your organization. https://docs.github.com/en/organizations/managing-organizati...

xyst2• 1 year ago

Pretty good timing on the attacker.

https://github.com/tj-actions/changed-files/tags?after=v35.9...

Most folks around the world signed off. B-squad probably left cleaning up remaining tasks or just fucking around with co-workers and pondering the weekend. Most GH actions run on a schedule (ie, backups of db, connecting to blob storage services).

Attacker(s) likely to extract plenty of secrets and exfil data before the alarms get triggered (if any) at companies.

The next data dumps are going to be wild.

harrisi5• 1 year ago

It's always been shocking to me that the way people run CI/CD is just listing a random repository on GitHub. I know they're auditable and you pin versions, but it's crazy to me that the recommended way to ssh to a server is to just give a random package from a random GitHub user your ssh keys, for example.

This is especially problematic with the rise of LLMs, I think. It's the kind of common task which is annoying enough, unique enough, and important enough that I'm sure there are a ton of GitHub actions that are generated from "I need to build and deploy this project from GitHub actions to production". I know, and do, know to manually run important things in actions related to ssh, keys, etc., but not everyone does.

sestep2• 1 year ago

The crazier part is, people typically don't even pin versions! It's possible to list a commit hash, but usually people just use a tag or branch name, and those can easily be changed (and often are, e.g. `v3` being updated from `v3.5.1` to `v3.5.2`).

harrisi5• 1 year ago

You and someone else pointed this out. I only use GitHub-org actions, and I just thought that surely there would be a "one version to rule them all" type rule.. how else can you audit things?

I've never seen anything recommending specifying a specific commit hash or anything for GitHub actions. It's always just v1, v2, etc.

nextts4• 1 year ago

Fuck. Insecure defaults again. I argue that a version specifier should be only a hash. Nothing else is acceptable. Forget semantic versions. (Have some other method for determining upgrade compatibility you do out of band. You need to security audit every upgrade anyway). Process: old hash, new hash, diff code, security audit, compatibility audit (semver can be metadata), run tests, upgrade to new hash.

remram3• 1 year ago

People don't pin versions. Referencing a tag is not pinning a version, those can be updated, and they are even with the official actions from GitHub.

harrisi5• 1 year ago

Aren't GitHub action "packages" designate by a single major version? Something like checkout@v4, for example. I thought that that designated a single release as v4 which will not be updated?

I'm quite possibly wrong, since I try to avoid them as much as I can, but I mean.. wow I hope I'm not.

jakub_g• 1 year ago

I think a big part of the problem is the way one typically "installs" a GH action: by copy-pasting something from README of the action.

Let's have a look at a random official GH provided action:

https://github.com/actions/checkout

It lists the following snippet:

`uses: actions/checkout@v4`

Almost everyone will just copy paste this snippet and call it a day. Most people don't think twice that v4 is a movable target that can be compromised.

In case of npm/yarn deps, one would often do the same, and copy paste `yarn install foobar`, but then when installing, npm/yarn would create a lockfile and pin the version. Whereas there's no "installer" CLI for GH actions that would pin the version for you, you just copy-paste and git push.

To make things better, ideally, the owners of actions would update the workflows which release a new version of the GH action, to make it update README snippet with the sha256 of the most recent release, so that it looks like

`uses: actions/checkout@abcdef9876543210` # v4.5.6

Since GitHub doesn't promote good defaults, it's not surprising that third-party maintainers do the same.

0rzech4• 1 year ago

Some people do actually pin versions, like me. For instance:

  - uses: Swatinem/rust-cache@f0deed1e0edfc6a9be95417288c0e1099b1eeec3 # v2.7.7

  - uses: subosito/flutter-action@f2c4f6686ca8e8d6e6d0f28410eeef506ed66aff # v2.18.0

It's a bit more manual work, but lepiej dmuchać na zimne (lit. it is better to blow on something cold), as the Polish proverb says.

kalaksi• 1 year ago

So much this. I recently looked into using GitHub Actions but ended up using GitLab instead since it had official tools and good docs for my needs. My needs are simple. Even just little scripting would be better than having to use and audit some 3rd party repo with a lot more code and deps.

And if you're new, and the repo aptly named, you may not realize that the action is just some random repo

tommasoamici• 1 year ago

Having to use actions for ssh/rsync always rubbed me the wrong way. I’ve recently taken the time to remove those in favor of using the commands directly (which is fairly straightforward, but a bit awkward).

I think it’s a failure of GitHub Actions that these third party actions are so widespread. If you search “GitHub actions how to ssh” the first result should be a page in the official documentation, instead you’ll find tens of examples using third party actions.

12_throw_away• 1 year ago

It's always been shocking to me that the way people run CI/CD is just listing a random repository on GitHub.

Right? My mental model of CI has always been "an automated sequence of commands in a well-defined environment". More or less an orchestrated series of bash scripts with extra sugar for reproducibility and parallelism.

Turning these into a web of vendor-locked, black-box "Actions" that someone else controls ... I dunno, it feels like a very pale imitation of the actual value of CI

naikrovek3• 1 year ago

I’ve been saying for a while that there aren’t supply chain problems when the supply chain is the problem.

I’m getting to the point where I feel that library use at all should be frowned upon, unless it is your own library, with obvious exceptions for the most widely used things like encryption and authentication. None of these things are particularly difficult, people just don’t want to do them “oh noes my velocity”

eviks2• 1 year ago

And writing your library should be frowned upon because you can easily add a major security vulnerability with your own two hands

naikrovek3• 1 year ago

If my library is left-padding a string with spaces, I don’t know how that could possibly introduce a major security vulnerability at all.

People write the trusted, secure code, and people retire from that work, and new people need to come in and do the work. Inexperienced people are going to be writing code no matter what.

So, you are either saying that no one should write new libraries because a major security vulnerability could be introduced by their hands, or you are saying that all libraries should be written by hands which will not introduce a major security vulnerability, and neither of those is at all feasible.

londons_explore2• 1 year ago

await exec.getExecOutput('bash', ['-c', `echo "aWYgW1sgIiRPU1RZUEUiID09ICJsaW51eC1nbnUiIF1dOyB0aGVuCiAgQjY0X0JMT

This malicious code isn't hard to recognise... Surely someone can run an LLM over all code in GitHub and just ask it 'does this code looks like it's blatantly trying to hide some malicious functionality'?

Then review the output and you'll probably discover far more cases of this sort of thing.

gkbrk• 1 year ago

What if before the command, there is also a code comment that says "this is not malicious, it has been manually verified by the engineers" and the LLM just believes it?

edoceo• 1 year ago

Noob question: is it possible to version lock these things? Could one "vendor" these tools into a fork and use that in the pipeline? Maybe it's one of those possible but crazy endeavour?

werrett6• 1 year ago

You can pin GitHub Actions to specific versions or specific commits. But note you can change version tags arbitrarily. In this specific case, the bad actor changes all of the version tags to point to their malicious commit: https://github.com/tj-actions/changed-files/tags

So to avoid that you'd have to pin your GitHub Action to specific commits as outlined in this SO post: https://stackoverflow.com/a/78905195

zahlman2• 1 year ago

In this specific case, the bad actor changes all of the version tags to point to their malicious commit: https://github.com/tj-actions/changed-files/tags

This required compromising the entire repository, yes? It can't be explained as the maintainer being tricked into merging something malicious?

nomilk• 1 year ago

I'd used GitHub Actions for at least 6-12 months before even realising <thing>/<thing> was not something that got parsed by the action (like a namespace and method/function), but was simply a reference to a github user name and repo. That whole object should really have been called a 'repo', because that's what it is, and that would alert users to use extreme caution whenever using one that wasn't created by themselves.

Griffinsauce• 1 year ago

Another fun fact related to this is that when someone changes their github username, their actions break. Just a hilariously bad design IMO. There should be a repository in between with immutable versions.

nextts4• 1 year ago

Well timed for the weekend. Some teams may notice Monday morning.

londons_explore2• 1 year ago

So this dumps env to stdout using some obfustucated code? And then relies on the fact logs are viewable publicly so the attacker can go scrape your secrets.

If so, why did they use obfustucated code? Seems innocuous enough to load env into environment vars, and then later to dump all env vars as part of some debug routine. Eg. 'MYSQL env var not set, mysql integration will be unavailable. Current environment vars: ${dumpenv}'

werrett6• 1 year ago

No idea. But they didn't do a great job -- they broke the action, which caused build failures that people were going to notice.

The malicious commit only landed at 09:57 PDT today (March 14) in one specific action (out of a number that is quite popular). Maybe they were planning on coming back and doing proper exfil?

mceachen2• 1 year ago

Presumably the cracker:

1. spoofed an account whose PRs were auto-merged (renovate[bot]) 2. found that `index.js` was marked as binary, and knew that GitHub is "helpful" (for the exploit), and hides diffs in the PR for that file by default 3. shoved the chunk of base64 wayyyy down the commit, so the maintainer had review fatigue by the time they scrolled. Having "memdump.py" in the commit in plaintext would certainly highlight the exploit more than the b64 string.

captn3m04• 1 year ago

Sounds about right to me. We can use a few knowns about GitHub IAM to deduce a few things:

1. There are no deleted PRs or Issues on the repo (2461..2463 are all valid refs)

2. A legitimate `Renovate[Bot]` dep bump would have filed a PR. Last such PR was 5 days ago, and is presumably not the source for this. (I haven't gone through every dep change, but doesn't look like it).

3. That leaves us with the 0e58ed867 commit, which has to be a spoofed commit, since it doesn't belong to a branch and we don't have a corresponding PR(1). A complete takeover of the repo can result in a hanging commit (by deleting the renovate bump branch), but there must be a hanging PR-ref around. Since there isn't one:

4. All of the above points to a compromised account that has write access to the repo.

There is also the https://github.com/tj-actions-bot account, but unclear if it has write access.

Edit: gurchik's guess at https://github.com/tj-actions/changed-files/issues/2463#issu... seems more likely:

1. Fork the repository > 2. Push compromised code to the fork 3. Update the tags in the parent repository to point to the SHA of the fork

cedws• 1 year ago

I called it:

https://cedwards.xyz/github-actions-are-an-impending-securit...

btown• 1 year ago

Does anyone know if https://github.com/tj-actions/verify-changed-files/ was compromised as well?

themgt• 1 year ago

This is hilarious, the maven-lockfile project "Lockfiles for Maven. Pin your dependencies. Build with integrity" appears to have auto-merged a PR for the compromised action commit. So the real renovate bot immediately took the exfiltration commit from the fake renovate bot and started auto-merging it into other projects:

https://github.com/chains-project/maven-lockfile/pull/1111

sureIy• 1 year ago

The fun part is that they used commits specifically for security, but then add an auto-updater. Might as well use tags.

mdaniel3• 1 year ago

heh, timing is everything https://github.com/chains-project/maven-lockfile/issues/1085...

After some cleanup the changed-files (https://github.com/tj-actions/changed-files) action seems to be more work to remove. It would be awesome if it could be added to the allowlist
Done. Allowed all versions of this action. Should I pin it to one version in the allowlist (won't be convenient if renovate updates this dependency)?

joshka• 1 year ago

Just leaving this here...

https://docs.github.com/en/actions/security-for-github-actio...

sangeeth96• 1 year ago

Don’t want to be alarmist but even if not using this action directly, I wonder what implications might be if this has leaked tokens from prominent public-facing project repos which might be used by several folks? I spotted an issue[1] to fix this in Expo EAS CLI and I’m guessing there are many more. The payload I saw from the report only seems to dump things to stdout but I guess analysis is still in progress and IDK if it’s the same payload for all the tags.

[1] https://github.com/expo/eas-cli/pull/2948/files

mdaniel3• 1 year ago

The semgrep URL about this seems to have won the submission lottery: https://news.ycombinator.com/item?id=43368870

mellosouls• 1 year ago

A list of projects claimed to be using it from the GitHub page:

https://github.com/tj-actions/changed-files?tab=readme-ov-fi...

jeeyoungk• 1 year ago

Looks like a lot of them are pinning to tags (which are not guaranteed to change) or SHA (https://github.com/vitejs/vite/blob/8da04227d6f818a8ad9efc00...) which is more hermetic.

gizzlon• 1 year ago

tags do not help, they're just a labelor a pointer

oefrha2• 1 year ago

https://github.com/tj-actions/changed-files/pull/2460

This kind of auto dependency bump bots are more trouble than their worth. If your app works today, bumping random deps won’t make it work better in any meaningful sense in 95% of cases. With such a small upside, the downside of introducing larger attack surfaces, subtle breakages (despite semver), major breakages, and in the worst cases, compromises (whether it’s a compromised dep, or fake bot commits that people are trained to ignore) just completely outweighs the upside. You’re on the fast lane to compromises by using this kind of crap.

People should really learn from Go’s minimum version selection strategy.

lostmsu• 1 year ago

Your app will have unpatched vulnerabilities.

oefrha2• 1 year ago

As long as you subscribe to security advisories, it’s a lot more likely that new vulnerabilities are introduced than old undiscovered vulnerabilities are accidentally patched. In fact barring rewrites (which usually won’t be picked up by semver-respecting auto bumps anyway) I can hardly think of an example of the latter.

rajbot• 1 year ago

This GitHub Action is still compromised, leaving thousands of repositories vulnerable.

Is there anyone here from GitHub that can help get this fixed?

captn3m04• 1 year ago

Helpful update: The gist author has deleted the gist, so https://gist.githubusercontent.com/nikitastupin/30e525b776c4... now results in a 404, and stops the action from any further secrets being leaked. This means you're impacted only if you used the action, and had a build triggered in the last 6 hours or so.

lmc• 1 year ago

Beautiful... 3rd party dependency exploit thwarted by its own 3rd party dependency.

Sytten• 1 year ago

I am surprised nobody here mentionned immutable github actions that are coming [1]. Been waiting for them since the issue was open in 2022. This would have significantly reduce impact and hopefully github will get it over the finish line.

I always fork my actions or at least use a commit hash.

[1] https://github.com/features/preview/immutable-actions

ricardobeat• 1 year ago

I thought actions were already immutable and published to a registry, not fetched directly from their repo. TIL.

Go also uses tags for module versioning, and while go.mod or package-lock.json stop this attack from reaching existing consumers, allowing remapping of all versions to the compromised one still expands the impact surface a lot. GitHub should offer a “immutable tags” setting for repos like these.

samschooler• 1 year ago

https://gist.github.com/gmatuz/7186f583df5f28196cc1f402af3bf...

This gist is pretty much the exact code, from the base64 encoded stuff. Looks like who ever put this in at least neafed the shell script.

gbraad• 1 year ago

Am I seeing this correctly, that a (fake/impersonation?) Renovate bot actually proposed the fix... and then other repositories trickled that fix in, also suggested by Renovate or Dependabot, as the dependency updated?

I usually fork (or create my own) actions, as I do not trust the whole chain on GitHub. The marketplace does no enforcement. It is really based on trust you have in the 3rd-party... and I do not have this; as many actions have side-effects, or only operate on a specific runner OS, etc.

brown9-2• 1 year ago

Renovate sending PRs to projects to upgrade their action version is unrelated to the original comment having a spoofed author of Renovate

Everdred2dx• 1 year ago

How does this siphon the secrets away? It looks like it just dumps them out to stdout and stops there.

varunsharma076• 1 year ago

Yes, just prints to the build log, so the risk is higher for public repos. Lot of public repos have creds printed in their build logs due to this compromised action.

stephenr• 1 year ago

I'm sorry I must be missing something.

The examples from the repo itself aren't helping to explain.

Why would anyone use this whole convoluted nodejs thing when `git diff-tree` exists?

I'm struggling to see a scenario where this isn't just part of some deliberately over complicated rube Goldberg setup.

globular-toast• 1 year ago

Shocked Pikachu anyone?

eacapeisfutuile4• 1 year ago

What is the current state? Tags reverted or still poisoned?

phantomathkg2• 1 year ago

User and repo all 404 now.

https://github.com/tj-actions

https://github.com/tj-actions/changed-files

eacapeisfutuile4• 1 year ago

Damn, so fully pulled, by authors, GitHub or adversary?

vimgrinder• 1 year ago

with all the AI stuff going around, can't github just scan repos for such malicious code?

prmph• 1 year ago

To me the only solution is that we need a security in depth approach:

- Create a trusted packages program, and mark trusted packages with a prominent badge. Package authors can apply to join the program, which will involve a review of their package and any subsequent updates. Ensure trusted packages can only depend on other trusted packages.

- Implement a capabilities model for package managers. I hear Deno is better in that respect.

- Have the package manager back-end use AI to continually review the packages. If anything suspicious is found, flag it and investigate manually.

- Require all packages to be name-spaced

carols10cents• 1 year ago

who is going to pay for the review of packages and updates? how do we know we can trust the reviewers?

github actions are name-spaced and that didn't help anything here...

ebfe14• 1 year ago

Doing a bit of investigation with github_events in clickhouse, it is quite clear that the accounts used to perform the attack was "2ft2dKo28UazTZ", "mmvojwip" also seems suspicious:

https://play.clickhouse.com/play?user=play#c2VsZWN0ICogZnJvb...

Actions taken by the threat actor at the time can be seen here:

https://play.clickhouse.com/play?user=play#c2VsZWN0ICogZnJvb...

ebfe14• 1 year ago

Note that these account seems to be deleted now - 2ft2dKo28UazTZ clearly did more than just changed-files and also seem to target coinbase/agentkit as well (Actually .. they might be targeted by the threat actor)

rognjen4• 1 year ago

That is a really very likely scenario.

The attacker was trying to compromise agentkit and found changed-files used in the repo so looked around. Found that it was using a bot with a PAT to release.

Totally possible the bot account had a weak password, and the maintainer said it didn't have 2FA.

They got the release bot PAT so they tried possibly quite an obvious vector that. They didn't need anything sophisticated or to exfil the credentials because agentkit is public.

It just so happened that it was detected before agentkit updated dependencies.

It's possible that with if thye had checked the dependabot config they could've timed it a bit better so that it's picked up in agentkit before being detected.

edit: Although, I don't think PATs are visible after they're generated?

ebfe14• 1 year ago

It seems i forgot to cater for the quota applied to free "play" user in ClickHouse in my previous query... In fact, the threat actor did a lot more... this should give a better list of actions that was performed - Clearly showed he was testing his payload:

https://play.clickhouse.com/play?user=play#c2VsZWN0ICogZnJvb...

DavyJone• 1 year ago

Nice find. Its a bit strange that the PRs listed there, are not present at all in the coinbase repo. Seems like the attack was directed there, but I also did not hear anything from Coinbase on this.

eg. Target their NPM and PYPI tokens, so they can push compromised packages.

skwashd• 1 year ago

The GitHub repo and org disappeared while I was poking around. Both https://github.com/tj-actions and https://github.com/tj-actions/changed-files return 404.

jtwaleson2• 1 year ago

Is there a safe fork somewhere?

kareemery• 1 year ago

Looking for one as well. My gh actions broke and looking for a drop in replacement.

Got this working with claude, would love if someone with more knowledge had thoughts:

```bash # Extract branch name from GITHUB_REF or GITHUB_HEAD_REF echo "current_branch=${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}" >> $GITHUB_OUTPUT # Determine if this is the default branch if [[ "${GITHUB_REF#refs/heads/}" == "${GITHUB_REF_NAME}" && "${GITHUB_REF_NAME}" == "${GITHUB_BASE_REF:-${GITHUB_REF_NAME}}" ]]; then echo "is_default=true" >> $GITHUB_OUTPUT else echo "is_default=false" >> $GITHUB_OUTPUT fi # Set default branch name echo "default_branch=${GITHUB_BASE_REF:-${GITHUB_REF_NAME}}" >> $GITHUB_OUTPUT ```

isamu_2000• 1 year ago

https://github.com/dorny/paths-filter ? looking into it.

Definitely going through and pinning all my 3rd party actions to specific commits e.g. party/package@<commitsha>.

jtwaleson2• 1 year ago

A colleague sent this: https://github.com/trmlabs/changed-files

hn8726• 1 year ago

I wish Github didn't just purge entire repositories/accounts in the event like this, although I know why they do this. But there's now no way to analyze the repository/exploit anymore

sathyabhat• 1 year ago

eacapeisfutuile4• 1 year ago

Was the entire repo just deleted from GitHub?

mmsc• 1 year ago

Paid Github organizations have a policy to block third-party actions. Would be nice if there was a way to allow third-party actions as long as they are referenced by hash, not version.

m4rtink2• 1 year ago

Another reason why you should be getting software via distro, with searate maintainers taking care of it there rather than directly from the developers that can inject malware via the very next version you mindlessly pull in without checking.

Also due to here being usually more than one distro, more people will look at the code & can spot the usptream getting rogue or getting compromised.

SAI_Peregrinus2• 1 year ago

Adding MITM to your chain of trust doesn't make it more trustworthy, it adds an extra possible attacker.

m4rtink2• 1 year ago

Often there is vetting before one becomes a distro maintainer & even if one of them gets compromised, the blast radius is at least limitted to that one distro, rather than "everyone" like in case of NPM & co. Non rolling distros aslo have various policies for package updates, making it much harder to get a compromised package to all supported distro versions before it is eventually discovered.

imoreno3• 1 year ago

Actually it does. The repo maintainer is on the user's side, so they are doing MITM on the attack vector. This makes it harder to get your malicious code in, because MITM might intercept it.

Yes now you have to trust the maintainer but that's sometimes easier.

rarkins• 1 year ago

Hi, Renovate author/maintainer here.

The affected repo has now been taken down, so I am writing this partly from memory, but I believe the scenario is:

1. An attacker had write access to the tj-actions/changed-files repo

2. The attacker chose to spoof a Renovate commit, in fact they spoofed the most recent commit in the same repo, which came from Renovate

3. Important: this spoofing of commits wasn't done to "trick" a maintainer into accepting any PR, instead it was just to obfuscate it a little. It was an orphan commit and not on top of main or any other branch

4. As you'd expect, the commit showed up as Unverified, although if we're being realistic, most people don't look at that or enforce signed commits only (the real bot signs its commits)

5. Kind of unrelated, but the "real" Renovate Bot - just like Dependabot presumably - then started proposing PRs to update the action, like it does any other outdated dependency

6. Some people had automerging of such updates enabled, but this is not Renovate's default behavior. Even without automerging, an action like this might be able to achieve its aim only with a PR, if it's run as part of PR builds

7. This incident has reminded that many people mistakenly assume that git tags are immutable, especially if they are in semver format. Although it's rare for such tags to be changed, they are not immutable by design

mlor• 1 year ago

Thanks for taking the time to comment. Not that it wasn't there before this, but this incident highlights a lot to take into consideration with respect to securing one's supply chain going forward.

diggan2• 1 year ago

6. Some people had automerging of such updates enabled, but this is not Renovate's default behavior. Even without automerging, an action like this might be able to achieve its aim only with a PR, if it's run as part of PR builds

I'm not sure how this could exploited by just making a PR, unless you for some reason have secrets enabled for builds by unknown contributors, which obviously would be a mistake. Usually, only builds using secrets only run on certain branches which has a known contributor approving the code before it gets there.

people mistakenly assume that git tags are immutable

If you're distributing a library on GitHub used by many other people/projects, then you really need to setup `protected branches` and `protected tags`, where you can prevent changes somewhat.

semiquaver2• 1 year ago

  > I'm not sure how this could exploited by just making a PR, unless you for some reason have secrets enabled for builds by unknown contributors

In this context the renovate bot would be making the PR to a repo it had been installed on, making it a trusted contributor able to trigger CI builds on its PRs.

jonenst• 1 year ago

Neither Branch Protection nor the newer Rulesets allow to protect secrets from someone with push acces to the repo. From what I understand, only environment secrets provide this feature (and have the drawback that you can't share them among multiple repos in the same org without copying them everywhere, although you can script the copying with the github api)

srvaroa• 1 year ago

7. This incident has reminded that many people mistakenly assume that git tags are immutable, especially if they are in semver format. Although it's rare for such tags to be changed, they are not immutable by design

IME, this will be more "learned" than "reminded". Many many people set up pipelines to build artefacts based on tags (e.g. a common practise being "on tag with some pattern, then build artefact:$tag") and are just surprised if you call out the flaws.

It's one of many practises adopted because everyone does it but without basic awareness of the tradeoffs. Semver is another similar case of inherited practise, where surprisingly many people seem to believe that labelling software with a particular string magically translates into hard guarantees about its behaviour.

nine_k• 1 year ago

Tags can be signed, and the signature can be verified. It's about as easy as signing / verifying commits. One can even make signing tags as the default option when creating tags.

This won't help in this case though, because a legitimate bot was tricked into working with a rogue commit; a tricked bot could as well sign a tag with a legitimate key.

"Immutable tags" of course exist, they are commit hashes, but they are uninformative :(

junon• 1 year ago

I theorized about this vulnerability a while back when I noticed new commits didn't disable automerging. This is an insane default from GH.

EDIT: seems GitHub has finally noticed (or started to care); just went to test this and auto merge has been seemingly disabled sitewide. Even though the setting is enabled, no option to automerge PRs shows up.

Seems I was right to worry!

EDIT2: We just tested this on GitLab's CI since they also have an auto-merge function and it appears they've done things correctly. Auto-merge enablement is only valid for the commit for which it was enabled; new pushes disable auto-merge. Much more sensible and secure.

klysm4• 1 year ago

How else should we do it?

3np• 1 year ago

So I follow steps 1-4 but don't see what triggered step 5, if they indeed just did an orphan commit outside of releases or main branch?

afitnerd• 1 year ago

Thanks for this writeup! It seems like #1 was the real weakness. Have you identified how the attacker was able to get write access to tj-actions/changed-files? Did this discovery result in any changes to how people can contribute to the project?

greatgib• 1 year ago

Honestly now most people doing "modern software engineering" are retards with no concept of real software engineering concepts.

Shitload of cardboard cto are pushing for "modern practice" to use whatever new version of whatever random dependency downloaded straight from internet.

Some persons asked why I don't like Ruff or UV for Python for example? You start a new job, first thing you have to do after installing a serious and safe Linux distribution like debian:

Curl whateverwebsite.com/ruff/download/latest | bash --blindly-execute --like-an-idiot

-> retrieving-random-dependancy1.tgz

-> executing-random-code...

And I don't speak about the current trend with "pre-commit" where a lot of persons are ok to have automatic downloads and execution on dev machines and ci, at each commit, of hundred of really totally random plugins from random places.

But this is a cto enforced decision to have this pre-commit for software quality...

trallnag2• 1 year ago

There are usually several different ways to install tools like uv. For example, uv is available as a Homebrew formula.

And regarding pre-commit: It usually relies on external code, but it is not a requirement. Pre-commit can also be used to just run arbitrary commands and scripts defined within the pre-commit config using the values "system" or "script" for the "language" key.

imglorp2• 1 year ago

Anybody have a snapshot of the good one, or maybe a drop in replacement? The repo is gone now.

thinkplay11• 1 year ago

Yup this would be super useful. Scouring about now trying to find

imglorp2• 1 year ago

This looks like it's three years old but it's a start.

https://github.com/actions-marketplace-validations/tj-action...

v1sionSec2• 1 year ago

As the repo is was taken down is someone able to tell me when was the malicious commit pushed. Trying to get a timeline to see if any workflows using this action were trigger in that timeframe. Thank you

imnotjames2• 1 year ago

Your secrets will be published to the CI log if you were affected.

I believe it's everything since around 10pm ET last night. I would consider any runs in the past 24 hours to be suspect.

v1sionSec2• 1 year ago

Thank you, unfortunately we have a multiple of repositories with multiple runs that use this action so checking the logs one by one will be hard. Any idea how to get all logs? Thank you

alper2• 1 year ago

Somewhere after 18:00 CET Friday.

MotiBanana• 1 year ago

Does anyone know if the secrets compromised were sent out, or just printed to stdout? We don't have any public repos using this action.

varunsharma076• 1 year ago

They were only printed to stdout and not sent out

alper2• 1 year ago

GitHub’s incident response to this took 17 hours give or take.

Actions is a paid service but Microsoft probably replaced all the security teams with AI.

onnimonni3• 1 year ago

It seems pretty awful that the de-facto way to use GitHub Actions is using git tags which are not immutable. For example to checkout code [1]:

- uses: actions/checkout@v4

Github does advise people to harden their actions by referring to git commit hashes [2] but Github currently only supports SHA-1 as hashing algorithm. Creating collisions with this hashing algo will be more and more affordable and I'm afraid that we will see attacks using the hash collisions during my lifetime.

I wish that they will add support for SHA-256 soon and wrote product feedback regarding it here: https://github.com/orgs/community/discussions/154056

If this resonates with you please go and give it a thumbs up :)

[1] https://github.com/actions/checkout?tab=readme-ov-file#usage

[2] https://docs.github.com/en/actions/security-for-github-actio...

onnimonni3• 1 year ago

I wasn't aware of the already existing SHA-1 collision support created by Github. It's very interesting read and AFAIK it seems that using SHA-1 collisions is not possible:

https://github.blog/news-insights/company-news/sha-1-collisi...

Is anyone aware of a git hook I could use to analyse my .github/workflows/*.yml files and replace git tags like "v4" with the current git commit hashes?

I think this would make it much safer to use 3rd party GitHub Actions.

Y_Y• 1 year ago

That's the sort of hook you should be able to write yourself pretty quickly. So I threw your comment into o3-mini-high and it gave me a decent-looking solution. Decent but wrong, since it thought "current git commit" referred to the project repo, rather than the referenced dependency.

Anyway here's the gist of a solution without any of the necessary checking that the files actually exist etc.

  #!/bin/sh
  for file in .github/workflows/*.yml; do
    grep -E "uses:[[:space:]]+[A-Za-z0-9._-]+/[A-Za-z0-9._-]+@v[0-9]+" "$file" | while read -r line; do
      repo=$(echo "$line" | sed -E 's/.*uses:[[:space:]]+([A-Za-z0-9._-]+\/[A-Za-z0-9._-]+)@v[0-9]+.*/\1/')
      tag=$(echo "$line" | sed -E 's/.*@((v[0-9]+)).*/\1/')
      commit_hash=$(git ls-remote "https://github.com/$repo.git" "refs/tags/$tag" | awk '{print $1}')
      [ -n "$commit_hash" ] && sed -i.bak -E "s|(uses:[[:space:]]+$repo@)$tag|\1$commit_hash|g" "$file" && git add "$file" && rm -f "$file.bak"
    done
  done
  exit 0

ffsm8• 1 year ago

... SHA-1 ... Collusions ... will be more and more affordable.

I can put your fears on that account to rest. At current trajectory, that's not gonna happen.

While a collision has been successfully produced, that's a very far milestone away from creating a specific collision with a payload you actually want to deliver with reasonable size so any sanity check such as a multi GB file size wouldnt "accidentally" detect it through timeouts in CI or similar.

This is so far beyond our current technological capabilities and Moore's law hasn't been active for over a decade now. Sure, we've had astounding success in the GPU space, but that's still not even remotely close to the previous trajectory while on Moore's Law.

deathanatos• 1 year ago

I've said this before, but in my mind the central problem in supply chain issues is this. Choose one:

1. You fix what version you're using to a fixed, immutable package. You receive no updates, no bug fixes, no security patches.

2. You follow a pointer to something like a API-compatible version, "latest" (#yolo) or ^5.0.0. You get bug fixes, security patches, but someone can push malicious updates.

Security types, IME, invariably want both: fix that package to a hash, so that we can't have a take over attack. But also we need to stay on top of updates, because we don't want to find out we have a decades old struct4j CVE buried in our codebase just waiting to be exploited.

So to accomplish "both", then we get into schemes like "fix the hashes … but we'll have a bot¹ update our dependency tree automatically". So like, #2, with more steps. Is anyone actually vetting that that update hash isn't going to compromise stuff? Hell no, no company is hiring that level of engineers; I'm lucky to have decent staffing for our primary concerns, reading the code in the dependency tree is out of the question.

And I'm sure in the coming days, security minded people will stampede in the general direction of #1. Stuff'll get fixed to hash, and stuff'll stop getting security patches.

IDK what the answer is, these seem pretty like fundamentally opposed forces of nature. The staffing problems aren't a technical problem, that's a capitalism problem, mostly in that there is very little to no penalty for a breach, so why would anyone hire the eng required to ensure the software works. There was hardly regulation in 2024, and any fines I did see regulatory bodies award are pittances, without fail. And, what regulation there was is now being actively dismantled.

There is some discussion of signed packages in this thread, and that's a helpful idea, I think, though I don't think it completely eliminates the problem: if the signing key is compromised, we're back to square one. The lay eng struggles with PKI.

¹While there is a bot of such nature (the renovate bot) somewhat tied up in this particular instance, I wouldn't over-focus on that bot, specifically; renovate, in particular, is not that relevant to the point I'm trying to make.

HALtheWise• 1 year ago

It seems like a 24hr delay for auto upgrades would mitigate a lot of this, maybe with some way that a trusted third-party could skip the delay for big-ticket zero day patches?

squiggleblaz• 1 year ago

I think what we need is first and third party notifications about vulnerabilities in specific versions, and a culture of cherry-picking security fixes onto previous versions. (In many cases, the same patch will apply to a previous version without any real difficulty.) First and third party notifications both provide critical roles; I think we've leaned too heavily on first party notifications only, but that's a SPOF.

rahulr06092• 1 year ago

For folks looking for a drop-in replacement for v45 (latest major version), we have a patched mirror here: https://github.com/trmlabs/changed-files

1] We took the public mirror from: https://code.forgejo.org/tj-actions/changed-files/src/tag/v4...

2] Undid the malicious code change: https://code.forgejo.org/tj-actions/changed-files/commit/0e5... - You can see the change here: https://github.com/trmlabs/changed-files/commit/8567847ee196...

3] Published under a v1 tag (since we can't vet historical releases and changes and didn't want folks to get confused)

If you want to contribute or report an issue, file a GH Issue or ping us at security@trmlabs.com

kurmiashish4• 1 year ago

Due to the ongoing security incident involving the tj-actions/changed-files Action, we at StepSecurity have provided a secure, drop-in replacement: step-security/changed-files.

We strongly advise replacing all instances of tj-actions/changed-files in your workflows with our secure alternative: https://github.com/step-security/changed-files

joonas• 1 year ago

Kudos for making this freely available, I was initially delighted to find out that there was a StepSecurity maintained alternative for the dorny/paths-filter action[1] as that seemed like a reasonable alternative to migrate to, but ended up being disappointed once I realized that it requires a subscription to use[2]

[1] https://github.com/step-security/paths-filter [2]: https://github.com/step-security/paths-filter/blob/b251c10d0...

rahulr06092• 1 year ago

@kurmiashish - If you and team are willing share your version without requiring a Step Security subscription today or in the future, happy to archive our repo and redirect users to Step

Thanks again for your timely detection and reporting!

kurmiashish4• 1 year ago

@rahulr0609 https://github.com/step-security/changed-files will forever remain free, and the community can use it without requiring a StepSecurity subscription.

frenchtoast85• 1 year ago

The repository is back online, with this explanation from the developer:

This attack appears to have been conducted from a PAT token linked to @tj-actions-bot account to which "GitHub is not able to determine how this PAT was compromised."
Account Security Enhancements
* The password for the tj-actions-bot account has been updated.
* Authentication has been upgraded to use a passkey for enhanced security.
* The tj-actions-bot account role has been updated to ensure it has only the minimum necessary permissions.
* GitHub proactively revoked the compromised Personal Access Token (PAT) and flagged the organization to prevent further exploitation.

https://github.com/tj-actions/changed-files/issues/2464#issu...

frenchtoast85• 1 year ago

Editing to add: the developer has locked further discussion about this. Very concerning as I believe their explanations are raising more questions than they are answering.

First of all, clearly Github can't answer for the developer how their bot's token was compromised, that's something the developer needs to find out. Instead they are repeating this statement like it's out of their hands.

But more concerningly, I don't believe the explanation is supported by the Github history which says the compromised commit was "authored" by Renovate and "pushed" by @jackton1. It's obvious how the first part was spoofed, but the second part is concerning as it indicates the @jackton1 account was compromised not @tj-actions-bot. If I'm missing something please let me know.

thj47422• 1 year ago

Check the timestamp on that commit push. It was from today, an hour or two before the repo was restored, not yesterday when the attack happened. The push actor != the committor or even the actual commit author, and there can be multiple push actors if the commit is pushed multiple times by different actors.

He probably just re-pushed the bad commit while trying to figure out how to fix this.

I find it very plausible that the bot token was compromised, not his user account token, as the attack was simply to push over the tags (which is something the automation bot would have access to do, as tag management is one of its functions)

mgiladi2• 1 year ago

We've recently released open-source tools that would have easily prevented this:

1. The maintainers could have used PRevent to immediately alert and block any PR containing malicious code, or easily configured it for detection in case of a direct push: https://github.com/apiiro/PRevent

2. Users could have used our malicious code detection ruleset to immediately detect and block it when scanning updates in all relevant CI/CD stages: https://github.com/apiiro/malicious-code-ruleset

3. For a better understanding of the detection, the malicious code falls precisely into the patterns presented in our research: https://apiiro.com/blog/guard-your-codebase-practical-steps-...

klysm4• 1 year ago

Malicious code detection is a fools errand. The attacker would’ve known that was installed and obfuscated it to avoid detection. It’s trivial to do so because they know what the detection is.

There is no way this would’ve prevented anything.

mgiladi2• 1 year ago

They have no way of knowing unless they have admin access, in which case they can do whatever they want anyway. If the tool produces any visible outputs, just configure it to block silently. That's on the maintainer side. On the consumer side, not even that discloses such use. Isn't it so?

Add behavioral detection, and you get a strong layer of defense, even if attackers know about it. You still want defense in depth as always, of course.

varunsharma076• 1 year ago

I’m Varun, CEO & Co-Founder of StepSecurity. StepSecurity detected and reported the tj-actions/changed-files compromise and has been actively helping the community recover from this incident.

To support you in understanding what happened and recovering swiftly, we’re hosting an Office Hour:

Date: March 17, 2025 Time: 10:00 AM Pacific Time (PT) Add to your calendar: https://www.addevent.com/event/Tf25207322

klysm4• 1 year ago

You can rename office hour to sales pitch

Tj-actions/changed-files GitHub Action Compromised – used by over 23K repos

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