Mathematica9.0.1 on Linux /tmp/MathLink vulnerability

Subject: Mathematica9.0.1 on Linux /tmp/MathLink vulnerability

The problem reported for Mathematica is present still at version 9.0.1,
both for the GUI and for the command-line interface.


Paul Szabo
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 on 7 May 2010, was assigned [TS 16194].

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