alt Hacker News> Bash starts before the download finishes ... Drop the connection mid-transfer and you get partial execution: a command like rm -r /usr/share/program can truncate to rm -r /usr. Commands ran, cleanup didn’t.
curl | bash scripts all define a function and then call it on the last line. This is a non issue in the real world.
> The server knows you’re piping — and can lie
This `sleep` based trick is always a cool demo to show freinds yes, but the server can also sneak in malware in a multitude of other ways given you're downloading code and binaries from them.
> You trust DNS, TLS, the CDN, and the origin simultaneously. A compromised CDN or BGP hijack delivers malware silently.
Well yes, that's how the internet works. If TLS of the server is really compromised, then the attacker will replace the checksum as well as the signing key. In real scenarios, you are going to be reading the signing key and checksum from the same domain. [1]
> You can’t reproduce what ran
`| tee inspect.sh | bash`
> Add sudo and it’s game over
Most credentials and important files live in the home directory, root is a red herring. If you're running it on shared server, then well... don't add sudo.
[1] Yes of course there are legitimate usecases for signing software. Common example: linux distros which are mirrored at many domains, but the checksum and signature are hosted on the canonical domain. But if I am curlbashing uv's install.sh from `astral.sh`, then doing signature verification using the public key hosted on the same astral.sh isn't adding much.
Replies
> curl | bash scripts all define a function and then call it on the last line. This is a non issue in the real world.
Please take a look at this before making any assertions... https://github.com/omlahore/RemoveMacAI/blob/main/install.sh
`| tee inspect.sh | bash`
Isn't that a bit like shutting the stable door after the horse has bolted?
I think that's missing the forest for trees. The problem with these curl-to-bash approaches is not that you are literally unable to intercept and inspect them with enough effort and planning.
The problem is that:
1. The effort and care needed to test is unnecessarily high. You've got to guard against way more tricks from an interactive source that can see you and choose what it's going to deliver and how.
2. With no "standard" artifact that can be exactly compared, that work cannot be shared.
In contrast, release_1.2.3.zip isn't going to mutate under you and everybody can agree on what its size/hash/bytes ought to be, and if it deviates from that it sets off alarm-bells.
> curl | bash scripts all define a function and then call it on the last line. This is a non issue in the real world.
Why would a convention often followed by good/careful actors bind what malicious/careless people create?