[NT] Microsoft XML Core Services XMLDOM Memory Corruption Vulnerability

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Microsoft XML Core Services XMLDOM Memory Corruption Vulnerability
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SUMMARY

<http://msdn2.microsoft.com/en-us/xml/default.aspx> XML Core Services
(also known as MSXML) is "a library for processing XML files. It works
with, and was original part of, Internet Explorer". Remote exploitation of
a buffer overflow vulnerability within Microsoft Corp.'s XML Core Services
may allow an attacker to execute arbitrary code in the context of the
current user.

DETAILS

Vulnerable Systems:
* Internet Explorer 6.x on Windows XP SP2

The vulnerability specifically exists in incorrect checking being
performed on the length argument to the substringData() method of an
XMLDOM object. When certain length values are supplied, a large region of
memory is copied into a buffer of insufficient size.

Analysis:
Exploitation of this vulnerability requires an attacker to convince a user
to open a page containing a malicious script.

In testing by iDefense Labs, code execution was determined to be possible.
Calling the vulnerable code with no other setup would simply cause the
application to write (or sometimes read) past the end of the allocated
memory and trigger an access violation exception. However, an attacker can
cause pointers in use by another thread to be overwritten and may be able
to execute code.

Workaround:
Disable active scripting, if it is not necessary for daily operations,
using the following steps.
1. In IE, click on Tools and select Internet Options from the drop-down
menu.
2. Click the Security tab and the Custom Level button.
3. Under Scripting, then Active Scripting, click the Disable radio
button.

Vendor response:
Microsoft has addressed this vulnerability within Microsoft Security
Bulletins MS07-042 and MS07-043. For more information, consult their
bulletins at the following URLs.
<http://www.microsoft.com/technet/security/Bulletin/MS07-042.mspx>

http://www.microsoft.com/technet/security/Bulletin/MS07-042.mspx

<http://www.microsoft.com/technet/security/Bulletin/MS07-043.mspx>

http://www.microsoft.com/technet/security/Bulletin/MS07-043.mspx

CVE Information:
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2223>
CVE-2007-2223

Disclosure Timeline:
05/17/2006 - Initial vendor notification
05/17/2006 - Initial vendor response
08/14/2007 - Coordinated public disclosure

ADDITIONAL INFORMATION

The information has been provided by
<mailto:idlabs-advisories@idefense.com> iDefense Labs Security Advisories.
The original article can be found at:
<http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=576>

http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=576

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