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Re: Mathematica8.0.4 on Linux /tmp/MathLink vulnerability
From: Vikram Dhillon <dhillonv10 () gmail com>
Date: Mon, 16 Apr 2012 14:54:00 -0400


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

- Vikram

On Sat, Apr 14, 2012 at 6:28 PM,  <paul.szabo () sydney edu au> wrote:
The problem reported for Mathematica became worse at version 8.0.4,
present for the command-line interface "math" also.


Paul Szabo   psz () maths usyd edu au   http://www.maths.usyd.edu.au/u/psz/
School of Mathematics and Statistics   University of Sydney    Australia



Paraphrasing what I wrote on 14 May 2010:

"Mathematica is the world's ultimate application for computations..."

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 () wolfram com on 7 May 2010, was assigned [TS 16194].

Vikram Dhillon

To perceive is to suffer.

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