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iDefense Security Advisory 05.12.09
http://labs.idefense.com/intelligence/vulnerabilities/
May 12, 2009

I. BACKGROUND

Microsoft PowerPoint is an application used for constructing
presentations, and comes with the Microsoft Office suite. For more
information, see the vendor's site found at the following link.

http://office.microsoft.com/en-us/powerpoint/default.aspx

II. DESCRIPTION

Remote exploitation of multiple stack-based buffer overflow
vulnerabilities in Microsoft Corp.'s PowerPoint could allow an attacker
to execute arbitrary code with the privileges of the current user.

The vulnerabilities exist within the importer for PowerPoint 4.0 format
files. This functionality is contained within the PP4X32.DLL.

The first vulnerability occurs when reading in a record header from the
file. Due to an incorrect buffer size calculation, it is possible to
overflow a stack-based buffer. Proper exploitation of this eventually
leads to control of the instruction pointer register, allowing for the
execution of arbitrary code.

The second vulnerability occurs when reading in record data from the
file. An integer is taken from the file, and used to control the number
of bytes to copy into a fixed size stack buffer. This leads to a
trivially exploitable stack-based buffer overflow.

III. ANALYSIS

Exploitation of these vulnerabilities results in the execution of
arbitrary code with the privileges of the user opening the file. To
exploit these vulnerabilities, an attacker needs to convince a user to
open a malicious file. After opening the file, no further interaction
is needed to trigger the vulnerability.

Since the vulnerabilities are stack-based buffer overflows, and it is
possible to overwrite SEH handlers or a frame pointer stored on the
stack, exploitation is relatively simple.

IV. DETECTION

iDefense has confirmed the existence of these vulnerabilities in the
following versions of PowerPoint:

PowerPoint 2000 SP3

PowerPoint XP SP3

PowerPoint 2003 SP2 and SP3 contain the vulnerable code, but by default
are unable to open PPT95 format files. This is due to the Office 2003
SP2/SP3 File Block Policy, which limits the file formats that Office
applications will open without special permissions. If the targeted
user has disabled the File Block Policy settings in PowerPoint 2003
SP3, then they are vulnerable. However, this is a non-default
configuration. More on this policy can be found at the following URL.

http://support.microsoft.com/kb/938810

Office 2007 and Office 2007 SP1 are not vulnerable to these issues.

V. WORKAROUND

Use the cacls program to deny access to the DLL containing the
vulnerable code, PP4X32.DLL. This will prevent the vulnerable DLL from
loading in PowerPoint, which will also prevent users from importing
PowerPoint 4.0 files. If Office 2003 SP3 is being used, then the
default behavior is to block the opening of PowerPoint 4.0 files. If
the default behavior has been changed, restoring it is an effective
workaround.

VI. VENDOR RESPONSE

Microsoft has released a patch which addresses this issue. For more
information, consult their advisory at the following URL:

http://www.microsoft.com/technet/security/Bulletin/MS09-017.mspx

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2009-0220 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

08/29/2008  - Initial Contact
08/29/2008  - Initial Response
08/29/2008  - PoC Requested
09/02/2008  - PoC Requested
09/03/2008  - PoC Sent
09/04/2008  - Vendor assigned case number
12/11/2008  - Status update received - no estimated release date
05/12/2009  - Coordinated Public Disclosure

IX. CREDIT

This vulnerability was reported to iDefense by Marsu.

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

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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 customerservice@idefense.com 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.
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