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Re: No shell => secure?
From: Ron DuFresne <dufresne () winternet com>
Date: Fri, 9 Jul 2004 09:29:40 -0500 (CDT)

This would be a form of security via obscurity and would be subject to all
the isues that rebound on basing secrutiy upon such.  In other words, it
might trip up a clueless-newbie/SK, but, in the ends would be easily
bypassed by anyone with half a clue.  Now, combining this with opther
methods of better security practises might help some sites.  But, if this
was made a standard in any vendors product, as soon as it was public
knowledge, with the release of the vendors OS relying upon such, it
becomes public knowledge and then 'obscurity' part become moot.


Ron DuFresne

On Thu, 8 Jul 2004, Matthias Benkmann wrote:

I can't say I've looked at much exploit-code so far but the POC exploits
to gain root I've seen for Linux all executed /bin/sh. I'd like to know if
this is true for in-the-wild exploits to root a box, too. If so, would it
be a useful security measure to rename /bin/sh and other shells (after
making sure that everything that needs them has been updated to the new
name, of course)?

I'm aware that a dedicated attacker who targets my box specifically will
not be stopped by this but I don't think I have such enemies. I also know
that DOS is still possible, but that's also not my concern. I'm simply
worried about script kiddies using standard exploits against random
servers on the Internet rooting my box faster than I can patch it.

If renaming the shell is not enough, how about renaming all of the
standard Unix top-level directories (such as /bin, /etc,...)? Would that
defeat standard exploits to root a box?


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