Additional technical information that describes the Microsoft Office Excel arbitrary code execution vulnerability is available.
Description
Microsoft Office Excel contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
The vulnerability is due to errors in processing malformed objects during the opening of Excel documents. An unauthenticated, remote attacker could exploit the vulnerability by convincing a user to view a malicious document. If the user views the document, the attacker could execute arbitrary code with the privileges of the user.
Microsoft has confirmed this vulnerability in a security bulletin and released software updates.
Warning Indicators
The following Microsoft products are affected:
Office Excel 2002 SP3 and prior
Office Excel 2003 SP3 and prior
Office Excel 2007 SP2 and prior
Office Excel Viewer SP2 and prior
Office 2004 for Mac
Office 2008 for Mac
Open XML File Format Converter for Mac
Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP2 and prior
IntelliShield Analysis
In order to exploit the vulnerability, an attacker must be able to convince a user to view a malicious document within Excel. The attacker may provide documents to the user as an attachment to an e-mail message or by providing links in e-mail or instant messages. An attacker may also use social engineering techniques in an attempt to convince users to open a provided document.
An exploit could allow the attacker to execute arbitrary code with the privileges of the user. Systems that grant users elevated privileges are at greatest risk, as any code execution would occur in a privileged security context, potentially allowing the attacker to take complete control over the system.
The Cisco Applied Intelligence team has created an Applied Mitigation Bulletin to address vulnerabilities that Microsoft disclosed in the March 2010 security bulletin release. This Cisco bulletin, which assists administrators in identifying or mitigating these vulnerabilities using Cisco devices, is available at the following link: Cisco Applied Mitigation Bulletin: Microsoft Security Bulletin Release for March 2010
Vendor Announcements
Microsoft has released a security bulletin at the following link: MS10-017
Impact
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary code with the privileges of the user. If that user holds elevated privileges, the attacker could execute arbitrary code resulting in a complete compromise.
Technical Information
The vulnerability is due to a type confusion error while parsing Excel documents. The application fails to properly identify a memory object shared between multiple document records. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious document. The processing of the document could allow an attacker to trigger a memory error. This error results from the incorrect identification of the type of memory object accessed by Excel. The application may access out-of-bounds memory, triggering memory corruption. The attacker could use the memory corruption to execute arbitrary code with the privileges of the user.
Safeguards
Administrators are advised to apply the available software updates.
Users are advised not to open unsolicited e-mail attachments. Users should verify that attachments are safe before opening them.
Users are advised to run applications with the least necessary privileges.
Users may consider applying the Microsoft Office Isolated Conversion Environment (MOICE) to safely open Excel files from suspicious or unrecognized sources on systems that are running Microsoft Office 2003 or Office 2007.
Administrators may consider using the Microsoft Baseline Security Analyzer (MBSA) scan tool to identify common security misconfigurations and missing security updates on system endpoints.
Patches/Software
Microsoft customers can obtain updates directly by using the links in the security bulletin. These updates are also distributed by Windows automatic update features and available on the Windows Update website. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
Signatures
Cisco Systems Cisco Intrusion Prevention System (IPS) 6.0
Version 1, March 9, 2009, 1:27 PM: Microsoft Office Excel contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code with the privileges of the user. Updates are available.
Alerts and bulletins on the Cisco Security Intelligence Operations Portal are highlighted by analysts in the
Cisco Threat Operations Center and represent a subset of the comprehensive content that is available through Cisco Security IntelliShield Alert Manager Service.
This customizable threat and vulnerability alert service provides security staff with access to timely, accurate, and credible information about threats and vulnerabilities that may affect their environment. Cisco is pleased to offer a free trial of the service.
To register for full access, please visit the IntelliShield trial registration page.
LEGAL DISCLAIMER The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.
