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Re: System users and valid shells...



On Mon, May 08, 2006 at 12:47:53PM +0100, Thiemo Seufer wrote:

> So you expect systems to become exploitable by mounting /usr as noexec
> when they provide some /usr/bin/foo shell?

Not actually "expect", but I would not be _that_ suprised. Most programs
that care about the login shell tend to run as root so a simple bug is
much more likely to become a security problem.

> Do you also expect this is more likely than an exploitable bug in
> /usr/sbin/nologin or /bin/false with their dependencies on ldso and
> glibc?

The code of nologin or false should be trivial. Spotting a place in some
complicated daemon where it fails to handle the "execve() returs an
error" case properly is much harder.

Gabor

-- 
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     MTA SZTAKI Computer and Automation Research Institute
                Hungarian Academy of Sciences
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