Microsoft XML Core Services XMLDOM Memory Corruption Vulnerability
iDefense Security Advisory 08.14.07
Aug 14, 2007
XML Core Services (also known as MSXML) is a library for processing XML
files. It works with, and was original part of, Internet Explorer. For
more information visit the following URL.
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.
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.
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.
iDefense confirmed the existence of this vulnerability using Internet
Explorer 6.x on Windows XP SP2. It is suspected that other versions are
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
2. Click the Security tab and the Custom Level button.
3. Under Scripting, then Active Scripting, click the Disable radio button.
VI. 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.
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-2223 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
VIII. DISCLOSURE TIMELINE
05/17/2006 Initial vendor notification
05/17/2006 Initial vendor response
08/14/2007 Coordinated public disclosure
The discoverer of this vulnerability wishes to remain anonymous.
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Copyright =A9 2007 iDefense, Inc.
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