Additional technical information is available to describe the Microsoft Office Web Components heap corruption vulnerability.
Description
Microsoft Office Web Components contain a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
This vulnerability is due to improper boundary restrictions on data that is processed by the Office Web Components ActiveX control. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious website. A successful exploit could allow the attacker to 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 applications are vulnerable:
Microsoft Office XP SP3 and prior
Microsoft Office 2003 SP3 and prior
Microsoft Office XP Web Components SP3 and prior
Microsoft Office 2003 Web Components SP3 and prior
Microsoft Internet Security and Acceleration Server 2004 Enterprise and Standard Edition SP3 and prior
Microsoft Internet Security and Acceleration Server 2006 SP1
Microsoft Office Small Business Accounting 2006
IntelliShield Analysis
Successful exploitation requires some form of user interaction. The attacker must convince a user to view a malicious website, possibly by providing links to users within e-mail messages, or posting malicious content on public websites in an attempt to launch exploits against any users that visit the site.
If an exploit is successful, the attacker could execute arbitrary code with the privileges of the user. End-host systems are at the greatest risk because users may hold Administrator privileges. On a system where the user holds elevated privileges, an attacker could execute code that results in a complete system compromise.
The Cisco Applied Intelligence team has created an Applied Mitigation Bulletin to address vulnerabilities that Microsoft disclosed in the August 2009 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 August 2009
Vendor Announcements
Microsoft has released a security bulletin at the following link: MS09-043
Impact
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary code with the privileges of the targeted user. If that user holds elevated privileges equivalent to the Administrator account, the attacker could execute code resulting in a complete system compromise.
Technical Information
This vulnerability is due to improper boundary restrictions on data that is processed by the Office Web Components ActiveX control. The OWC10.Spreadsheet.10 ActiveX control fails to properly check the length of data that is sent a specific order of methods. The processing of malicious data could trigger a heap overflow, which could result in memory corruption.
An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a website that is designed to instantiate the vulnerable ActiveX control and submit malicious data to that control. The processing of the malicious data could cause memory corruption that the attacker could leverage to execute arbitrary code with the privileges of the user.
Safeguards
Administrators are advised to apply the appropriate updates.
Administrators may consider configuring Internet Explorer to prompt users before running Active Scripting or ActiveX controls by setting the Internet and Local Intranet security zone settings to High. Alternately, administrators could disable Active Scripting and ActiveX controls in these security zones.
Administrators are advised to prevent the Office Web Component ActiveX Control from running in Internet Explorer by setting the kill bit on the following CLSIDs:
Administrators are advised to unregister the Office Web Components owc10.dll and owc11.dll libraries.
Users are advised not to visit websites or follow links that have suspicious characteristics or cannot be verified as safe.
Users are advised to run applications with the least privileges necessary.
Administrators are advised to implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit this vulnerability.
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, August 11, 2009, 2:12 PM: Microsoft Office Web Components contain a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
The security vulnerability applies to the following combinations of products.
Primary Products:
Microsoft, Inc.
ISA Server
2004 Base, SP1, SP2, SP3 | 2006 Base, SP1
Microsoft, Inc.
Office
2003 Base, Multilingual User Interface Pack, SP1, SP2, SP3 | XP (2002) Base, SP1, SP2, SP3
Microsoft, Inc.
Office Small Business Accounting
2006 Base
Microsoft, Inc.
Office Web Components (OWC)
10 (Office XP) Base | 11 (Office 2003) Base
Associated Products:
N/A
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