iDefense Security Advisory 04.17.08 http://labs.idefense.com/intelligence/vulnerabilities/ Apr 17, 2008 I. BACKGROUND OpenOffice is an open-source desktop office suite for many of today's popular operating systems. One of the file formats that OpenOffice supports is Quattro Pro (QPRO). This format is used by Corel's QuattroPro spreadsheet application. More information is available from the following URL. http://www.openoffice.org/ II. DESCRIPTION Remote exploitation of an integer underflow vulnerability in OpenOffice, as included in various vendors' operating system distributions, allows attackers to execute arbitrary code with the privileges of the logged in user. The vulnerability exists within the code responsible for converting the QPRO file into an internal representation used by OpenOffice. A 16-bit integer is read in from the file, and later used as a loop counter that controls how many values are stored into local stack buffers. When verifying the value of this counter, the code decrements the counter without checking to see if this operation will underflow. This results in the loop running for many iterations, which leads to a stack based buffer overflow. This allows for the execution of arbitrary code. III. ANALYSIS Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user opening the file. In order to exploit this vulnerability, an attacker must persuade a user to open a malicious file. IV. DETECTION iDefense has confirmed the existence of this vulnerability in OpenOffice version 2.3. Other versions may also be affected. V. WORKAROUND Renaming the shared library that contains the vulnerable code will prevent OpenOffice from opening QPRO files. On Fedora Core 7, the library can be found at: /usr/lib/openoffice.org/program/libsc680li.so Renaming this file to libsc680li.so.bak will prevent it from being loaded. In addition to preventing the use of QPRO files, this also prevents users from opening various other file formats. VI. VENDOR RESPONSE The OpenOffice.org team has addressed this vulnerability with the release of version 2.4. For more information, consult the OOo Security Bulletin at the following URL. http://www.openoffice.org/security/cves/CVE-2007-5745.html VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2007-5747 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 10/29/2007 Initial vendor notification 10/30/2007 Initial vendor response 04/17/2008 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 © 2008 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@xxxxxxxxxxxx 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.
