iDefense Security Advisory 08.06.09: Microsoft Internet Explorer HTML TIME 'ondatasetcomplete' Use After Free Vulnerability

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

iDefense Security Advisory 07.28.09
http://labs.idefense.com/intelligence/vulnerabilities/
Jul 28, 2009

I. BACKGROUND

HTML+TIME (HTML Timed Interactive Multimedia Extensions)is a web
standard that was created for Microsoft Corp.'s Internet Explorer (IE)
to allow web page authors to create timed animation content on a web
page. This is accomplished using an XML like markup that makes use of
HTML+TIME properties and elements. Internet Explorer supports this
markup standard, and also exposes a scripting interface for interacting
with the HTML+TIME elements on the page. For more information, please
see the vendor's web page at the following link:

http://technet.microsoft.com/en-us/library/ms533099(VS.85).aspx

II. DESCRIPTION

Remote exploitation of a use after free vulnerability in Microsoft
Corp.'s Internet Explorer could allow an attacker to execute arbitrary
code with the privileges of the current user.

The vulnerability occurs when the 'ondatasetcomplete' event method of a
timeChildren object is referenced. If this occurs when the object is in
an inconsistent state, a heap chunk will be freed, and then reused after
being freed. This results in an uninitialized VTABLE being used, which
can result in the execution of arbitrary code when the pointer is
dereferenced.

III. ANALYSIS

Exploitation of this vulnerability results in the execution of arbitrary
code with the privileges of the user viewing the web page. To exploit
this vulnerability, a targeted user must load a malicious web page
created by an attacker. An attacker typically accomplishes this via
social engineering or injecting content into compromised, trusted
sites. After the user visits the malicious web page, no further user
interaction is needed.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in Internet
Explorer versions 6, 7, and 8. Internet Explorer 5 does not appear to
be vulnerable.

V. WORKAROUND

Since this vulnerability is triggered through script code, disabling
Active Scripting will prevent the exploitation of this vulnerability.

VI. VENDOR RESPONSE

Microsoft Corp. has released an Out-Of-Band patch which addresses this
issue. Information about downloadable vendor updates can be found by
clicking on the URLs shown.

http://www.microsoft.com/technet/security/Bulletin/MS09-034.mspx

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2009-1917 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

05/06/2009 - PoC Requested
06/06/2009 - PoC Sent
06/24/2009 - Tentative disclosure set to August
06/25/2009 - Requested CVE from vendor
06/25/2009 - Received CVE from vendor
07/23/2009 - Received updated disclosure notice for OOB in July
07/28/2009 - Coordinated public disclosure

IX. CREDIT

This vulnerability was reported to iDefense by Peter Vreugdenhil.

Get paid for vulnerability research
http://labs.idefense.com/methodology/vulnerability/vcp.php

Free tools, research and upcoming events
http://labs.idefense.com/

X. LEGAL NOTICES

Copyright © 2009 iDefense, Inc.

Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDefense. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically,
please e-mail [email protected] for permission.

Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct,
indirect, or consequential loss or damage arising from use of, or
reliance on, this information.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (MingW32)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/

iD8DBQFKe0W1bjs6HoxIfBkRAlQLAKCJHohcKfI8Emv5OfSk7LMotPL/7ACfb4Wa
JyhMGxPvQ4AfdaK6dfmcIlg=
=OPoC
-----END PGP SIGNATURE-----