iDefense Security Advisory 04.12.11 http://labs.idefense.com/intelligence/vulnerabilities/ Apr 12, 2011 I. BACKGROUND Excel is the spreadsheet application included with Microsoft Corp.'s Office productivity software suite. More information is available at the following website: http://office.microsoft.com/excel/ II. DESCRIPTION Remote exploitation of a memory corruption vulnerability in Microsoft Corp.'s Excel could allow an attacker to execute arbitrary code with the privileges of the current user. The vulnerability occurs when Excel parses a specially crafted Excel file. Specific values within this file can trigger a memory corruption vulnerability and may allow arbitrary code execution. III. ANALYSIS Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user opening the file. To exploit this vulnerability, an attacker needs to convince a user to open a malicious file. Attackers typically accomplish this by e-mailing a targeted user the file or hosting the file on a Web page. IV. DETECTION The following Microsoft products are vulnerable: V. WORKAROUND The vulnerability occurs in the core parsing code of Excel, and this code can not be disabled; however, it is possible to disable the opening of the older binary format files and use MOICE to convert the file to the newer XML-based format. VI. VENDOR RESPONSE Microsoft Corp. has released patches which address this issue. Information about downloadable vendor updates can be found by clicking on the URLs shown. http://www.microsoft.com/technet/security/bulletin/ms11-021.mspx VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2011-0103 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 09/09/2010 Initial Vendor Notification 09/09/2010 Initial Vendor Reply 04/12/2011 Coordinated Public Disclosure IX. CREDIT The discoverer of this vulnerability wishes to remain anonymous. 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 © 2011 Verisign 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.