ZDI-11-040: Microsoft Office Excel 2003 Invalid Object Type Remote Code Execution Vulnerability

http://www.zerodayinitiative.com/advisories/ZDI-11-040

February 7, 2011 - This vulnerability is being disclosed publicly without a patch in accordance with the ZDI 180 day deadline. To view mitigations for this vulnerability please see: http://dvlabs.tippingpoint.com/blog/2011/02/07/zdi-disclosure-microsoft

-- CVSS:
9, (AV:N/AC:L/Au:N/C:P/I:P/A:C)

-- Affected Vendors:
Microsoft

-- Affected Products:
Microsoft Office Excel

-- TippingPoint(TM) IPS Customer Protection:
TippingPoint IPS customers have been protected against this
vulnerability by Digital Vaccine protection filter ID 10818. 
For further product information on the TippingPoint IPS, visit:

    http://www.tippingpoint.com

-- Vulnerability Details:
This vulnerability allows remote attackers to execute arbitrary code on
vulnerable installations of Microsoft Office Excel. User interaction is
required to exploit this vulnerability in that the target must visit a
malicious page or open a malicious file.

The flaw occurs when parsing a document with a malformed Excel document.
When parsing an office art object, the application will add the
malformed object to a linked list. After this addition, the application
will process each element in the linked list. When handling the object
in question, the application will explicitly trust a function pointer
off of this object. If an attacker can substitute an object of their
choosing in place of this function pointer, code execution under the
context of the application can be achieved.

-- Disclosure Timeline:
2010-07-20 - Vulnerability reported to vendor
2011-02-07 - Public release of advisory

-- Credit:
This vulnerability was discovered by:
    * Anonymous

-- About the Zero Day Initiative (ZDI):
Established by TippingPoint, The Zero Day Initiative (ZDI) represents 
a best-of-breed model for rewarding security researchers for responsibly
disclosing discovered vulnerabilities.

Researchers interested in getting paid for their security research
through the ZDI can find more information and sign-up at:

    http://www.zerodayinitiative.com

The ZDI is unique in how the acquired vulnerability information is
used. TippingPoint does not re-sell the vulnerability details or any
exploit code. Instead, upon notifying the affected product vendor,
TippingPoint provides its customers with zero day protection through
its intrusion prevention technology. Explicit details regarding the
specifics of the vulnerability are not exposed to any parties until
an official vendor patch is publicly available. Furthermore, with the
altruistic aim of helping to secure a broader user base, TippingPoint
provides this vulnerability information confidentially to security
vendors (including competitors) who have a vulnerability protection or
mitigation product.

Our vulnerability disclosure policy is available online at:

    http://www.zerodayinitiative.com/advisories/disclosure_policy/

Follow the ZDI on Twitter:

    http://twitter.com/thezdi