this post was submitted on 13 Mar 2025
275 points (96.6% liked)

Linux

6450 readers
590 users here now

A community for everything relating to the GNU/Linux operating system

Also check out:

Original icon base courtesy of lewing@isc.tamu.edu and The GIMP

founded 2 years ago
MODERATORS
 

curl https://some-url/ | sh

I see this all over the place nowadays, even in communities that, I would think, should be security conscious. How is that safe? What's stopping the downloaded script from wiping my home directory? If you use this, how can you feel comfortable?

I understand that we have the same problems with the installed application, even if it was downloaded and installed manually. But I feel the bar for making a mistake in a shell script is much lower than in whatever language the main application is written. Don't we have something better than "sh" for this? Something with less power to do harm?

you are viewing a single comment's thread
view the rest of the comments
[–] FizzyOrange@programming.dev 1 points 19 hours ago (3 children)

No it isn't. What could a Bash script do that the executable it downloads couldn't do?

[–] moonpiedumplings@programming.dev 2 points 12 hours ago (1 children)

It's not just protection against security, but also human error.

https://github.com/MrMEEE/bumblebee-Old-and-abbandoned/issues/123

https://hackaday.com/2024/01/20/how-a-steam-bug-once-deleted-all-of-someones-user-data/

Just because I trust someone to write a program in a modern language they are familier in, doesn't mean I trust them to write an install script in bash, especially given how many footguns bash has.

[–] FizzyOrange@programming.dev 1 points 10 hours ago (1 children)

Hilarious, but not a security issue. Just shitty Bash coding.

And I agree it's easier to make these mistakes in Bash, but I don't think anyone here is really making the argument that curl | bash is bad because Bash is a shitty error-prone language (it is).

Definitely the most valid point I've read in this thread though. I wish we had a viable alternative. Maybe the Linux community could work on that instead of moaning about it.

[–] moonpiedumplings@programming.dev 1 points 3 hours ago (1 children)

Hilarious, but not a security issue. Just shitty Bash coding.

It absolutely is a security issue. I had a little brain fart, but what I meant to say was "Security isn't just protection from malice, but also protection from mistakes".

Let's put it differently:

Hilarious, but not a security issue. Just shitty C coding.

This is a common sentiment people say about C, and I have a the same opinion about it. I would rather we use systems in place that don't give people the opportunity to make mistakes.

I wish we had a viable alternative. Maybe the Linux community could work on that instead of moaning about it.

Viable alternative for what? Packaging.

I personally quite like the systems we have. The "install anything from the internet" is exactly how Windows ends up with so much malware. The best way to package software for users is via a package manager, that not only puts more eyes on the software, but many package managers also have built in functionality that makes the process more reliable and secure. For example signatures create a chain of trust. I really like Nix as a distro-agnostic package manager, because due to the unique way they do things, it's impossible for one package's build process to interfere with another.

If you want to do "install anything from the internet" it's best to do it with containers and sandboxing. Docker/podman for services, and Flatpak for desktop apps, where it's pretty easy to publish to flathub. Both also seem to be pretty easy, and pretty popular — I commonly find niche things I look at ship a docker image.

[–] FizzyOrange@programming.dev 1 points 54 minutes ago

This is a common sentiment people say about C, and I have a the same opinion about it. I would rather we use systems in place that don’t give people the opportunity to make mistakes.

The issue with C is it lets you make mistakes that commonly lead to security vulnerabilities - allowing a malicious third party to do bad stuff.

The Bash examples you linked are not security vulnerabilities. They don't let malicious third parties do anything. They done have CVEs, they're just straight up data loss bugs. Bad ones, sure. (And I fully support not using Bash where feasible.)

Viable alternative for what? Packaging.

A viable way to install something that works on all Linux distros (and Mac!), and doesn't require root.

The reason people use curl | bash is precisely so they don't have to faff around making a gazillion packages. That's not a good answer.

[–] jagged_circle@feddit.nl 1 points 16 hours ago (1 children)

You're telling me that you dont verify the signatures od the binaries you download before running them too?!? God help you.

I download my binaries with apt, which will refuse to install the binary if the signature doesn't match.

[–] FizzyOrange@programming.dev 0 points 10 hours ago (1 children)

No because there's very little point. Checking signatures only makes sense if the signatures are distributed in a more secure channel than the actual software. Basically the only time that happens is when software is distributed via untrusted mirror services.

Most software I install via curl | bash is first-party hosted and signatures don't add any security.

[–] jagged_circle@feddit.nl 0 points 5 hours ago (1 children)

All publishing infrastructure shouldn't be trusted. Theres countless historical examples of this.

Use crypto. It works.

[–] FizzyOrange@programming.dev 1 points 52 minutes ago

Crypto is used. It is called TLS.

You have to have some trust of publishing infrastructure, otherwise how do you know your signatures are correct?

[–] easily3667@lemmus.org 1 points 17 hours ago* (last edited 17 hours ago) (1 children)

By definition nothing

The point you appear to be making is "everything is insecure so nothing is" and the point others are making is "everything is insecure so everything is"

[–] FizzyOrange@programming.dev 1 points 11 hours ago

No, the point I am making is there are no additional security implications from executing a Bash script that someone sends you over executing a binary that they send you. I don't know how to make that clearer.