Follow up: How to write a Linux virus [LWN.net]

Follow up: How to write a Linux virus

Posted Feb 13, 2009 19:35 UTC (Fri) by tzafrir (subscriber, #11501)
In reply to: Follow up: How to write a Linux virus by droundy
Parent article: Follow up: How to write a Linux virus

What is "internet"? So the browser should not be allowed to save files on the disk? Any time you download a file you'll have to explicitly enable it? So you'll get used to that and enable it for that new "harmless" desktop file.

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Follow up: How to write a Linux virus

Posted Feb 14, 2009 11:34 UTC (Sat) by etienne_lorrain@yahoo.fr (guest, #38022) [Link] (1 responses)

The user/account "internet" has, like any user on Unix, a directory usually named /home/internet, it can do whatever it wants there (like installing any kind of virus, or doing rm -rf .*). You can set any limit for this untrusted user by ulimit.
The user "internet" has access to the local screen (if the real user didn't do "xhost -"), and the sound card.
The browser downloads an untrusted executable file, keep it executable and set the set-uid bit and owner "internet", and put that on the desktop.
The real user can click on this icon and run it without checks, the worst which can happen is that all "internet" user files will have a virus.
That postcard with sound example can be viewed without problem.

Note that I do not know about downloaded data files, maybe it would be safer to to the same system (owner "internet") and open the viewer under the "internet" account in case the data tries to exploit a security bug of the viewer - but that is not the initial problem we were talking about.

Follow up: How to write a Linux virus

Posted Feb 19, 2009 14:53 UTC (Thu) by mrshiny (guest, #4266) [Link]

So you're basically suggesting a user run their browser under a different user account, to sandbox it. One disadvantage I can see is that many people would never bother to change the ownership of the "internet"'s files and, if infected, would end up with a lot of data at risk for loss/theft. Also, if a file is not de-sandboxed in a timely fashion, a later infection can modify data the user has already "vetted". This increases the risk of infected files escaping the sandbox, when the user decides they finally want to copy that mp3 to their music folder.