this post was submitted on 05 Dec 2023
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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
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Either you're trolling - in which case, sod off back to Reddit - or you have a woeful misunderstanding of how Linux user permissions work.
Please explain how someone might "simply change" someone else's .bashrc without either already having access to that user account, or root access on the whole machine?
The idea is malware you installed would presumably run under your user account and have access. You could explicitly give it different UIDs or even containerize it to counteract that, but by default a process can access everything it's UID can, which isn't great. And even still to this day that's how users execute a lot of processes.
Windows isn't much better here, though.
If you containerize, the application (malware) will run under the user configured in the image, unless you override it, and in a separate mount namespace, unless you change that, which makes the "alias sudo" trick extremely unlikely.
Even running under a separate user anyway prevents almost fully the attack you mention, unless the separate user has root privileges or the DAC_OVERRIDE capability is assigned to the binary (assigning it requires CAP_SYS_ADMIN).
In short, the attack you mention is a common persistence and privilege escalation vector, which is relatively easy to detect (watch for changes to shell profiles), although preventing it requires some care. I just want to point out that in single-user machines (e.g. personal computers) escalating to root is anyway fairly unnecessary, given that all the juicy stuff (ssh keys, data, etc.) is anyway probably running under/owned by that user.
Yep! You can also get pretty far even without containers. At the end of the day containers are just sandboxing using namespaces, and
systemdcan expose that pretty trivially for services, and tools like bubble wrap / flatpak let you do it for desktop apps. In an ideal world every package would only use the namespaces it needs, and stuff like this would largely not be a concern.