this post was submitted on 13 Mar 2025
276 points (96.6% liked)
Linux
6466 readers
701 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
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
It is actually a passive detection based of the timing of the chunk requests. Because curl by default will only request new chunks when the buffer is freed by the shell executing the given commands. This then can be used to detect that someone is not merely downloading but simultaneously executing it. Here's a writeup about it:
https://web.archive.org/web/20250209133823/https://www.idontplaydarts.com/2016/04/detecting-curl-pipe-bash-server-side/
You can also find some proof-of-concept implementations online to try it out yourself.
Wow, thanks for this. That is very helpful context. And thanks for your original post too, or I'd never have asked.
Oh, you're welcome, kind person :)