Directory Traversal in Wolfram Research's webMathematica

["Andrew Badr" <andrewbadr () hotmail com>]

Security Advisory
By Andrew Badr
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SUMMARY:

There is a vulnerability in the webMathematica software which allows remote 
clients (web surfers) to read an arbitrary file on the server (assuming the 
httpd-user has permission). This can reveal sensitive information such as 
that stored in /etc/passwd, /etc/inetd.conf, system logs, etc. (These 
examples are on UNIX -- note that Windows servers are also vulnerable.)

Software Publisher: Wolfram Research

Software Title: webMathematica

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Software Description: http://www.wolfram.com/  says:

"webMathematica is the clear choice for adding interactive calculations to 
the web. This unique technology enables you to create web sites that allow 
users to compute and visualize results directly from a web browser.

Based on the world's leading technical computing software and the proven 
Java Servlet technology, webMathematica is fully compatible with Mathematica 
and state-of-the-art dynamic web systems."


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Vulnerability type:  Directory traversal

Vunlerability details: webMathematica generates images based on user input, 
often involving mathematical figures or signs which cannot be displayed 
using normal ascii-text. Generated images are named a long numeric string 
(randomly generated?) and are displayed in the page presented to the user. 
The ID of the image is passed to a cgi-script as an argument the URL, as 
shown below, and altering this ID can trick the script into displaying other 
files on the system.

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Exploit:

Example normal URL:
http://www.domain.com/webMathematica/MSP?MSPStoreID=MSPStore888808189_2408042780&MSPStoreType=image/gif


Example exploited URL:
http://www.domain.com/webMathematica/MSP?MSPStoreID=../../../../../etc/passwd&MSPStoreType=image/gif


Note that the normal user would never see the above 'normal' URL, as the URL 
only refers the generated image. It is found by viewing the page source, or 
through browser-specific methods. In Internet Explorer, for example, one 
would right-click on the generated image and click 'Properties'.


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Possible Workaround: Directly reference the generated image, thereby 
avoiding use of the 'MSP' script.

Problem Elimination: Wolfram Research was able to fix this problem within 
hours of notification.

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More info:

Encoded characters like %20 ( ), %22 ("), %3B (;) are all decoded in the 
script but I can't find a way to escape the display command, whatever it is, 
to e.g. execute a file.

For different file types, changing the MSPStoreType argument from 
"image/gif" to "text" may give better results.

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The vendor HAS been notified of this vulnerability.
The software has been fixed.


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-Andrew Badr



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