bugtraq - Re: Mathematica8.0.4 on Linux /tmp/MathLink vulnerability

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Date: Mon, 16 Apr 2012 14:54:00 -0400
From: Vikram Dhillon <dhillonv10@...il.com>
To: paul.szabo@...ney.edu.au
Cc: bugtraq@...urityfocus.com, full-disclosure@...ts.grok.org.uk
Subject: Re: Mathematica8.0.4 on Linux /tmp/MathLink vulnerability

Hello,

One quick fix here could be to change user permissions with chmod or
add a new group where Mathematica in /tmp doesn't have permissions to
anything under /home so then even if a user is compromised, the
symlink won't work because the user doesn't have permissions. A root
user here is an entirely different problem, here an attacker can
symlink to any directory. So a new group to setup permissions for
Mathemtica /tmp access would be a better idea. Will look into a patch
soon.

- Vikram

On Sat, Apr 14, 2012 at 6:28 PM,  <paul.szabo@...ney.edu.au> wrote:
> The problem reported for Mathematica became worse at version 8.0.4,
> present for the command-line interface "math" also.
>
> Cheers,
>
> Paul Szabo   psz@...hs.usyd.edu.au   http://www.maths.usyd.edu.au/u/psz/
> School of Mathematics and Statistics   University of Sydney    Australia
>
>
> ---
>
> http://lists.grok.org.uk/pipermail/full-disclosure/2010-May/074548.html
> http://www.securityfocus.com/archive/1/511298
> http://www.securityfocus.com/bid/40169
>
>
> Paraphrasing what I wrote on 14 May 2010:
>
> "Mathematica is the world's ultimate application for computations..."
> http://www.wolfram.com/products/
>
> Mathematica on Linux uses the /tmp/MathLink directory in insecure ways.
> Mathematica creates or re-uses an existing /tmp/MathLink directory, and
> overwrites files within and follows symlinks. This type of behaviour is
> "known unsafe" on multi-user machines e.g. University login servers.
> As a classic example of a symlink attack, if an "attacker" uses:
>
> mkdir /tmp/MathLink; ln -s /home/victim/.bashrc /tmp/MathLink/.shmsrec
>
> then when the victim runs Mathematica his ~/.bashrc will be clobbered.
> New files are created world-writable, allowing a complete compromise of
> the user account by linking to ~/.bash_logout . (If root ever uses
> Mathematica then the damage is greater.)
>
> There is no workaround: the command-line math interface is also unsafe.
>
> Notified support@...fram.com on 7 May 2010, was assigned [TS 16194].



-- 
Regards,
Vikram Dhillon

~~~
To perceive is to suffer.