Additional technical information is available for the Microsoft Office Web Components memory allocation vulnerability.
Description
Microsoft Office Web Components contain a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
The vulnerability is due to a flaw with the loading and unloading of a control in Microsoft Office Web Components. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious website. If the user views the site, 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 that correct it.
Warning Indicators
The following applications are affected:
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
Attackers cannot directly exploit this vulnerability and instead must rely on user interaction to accomplish an exploit. To convince users to visit malicious sites, attackers may send targeted e-mail messages with embedded links combined with text instructions. An attacker may also inject malicious content into public websites or compromised websites in the hopes that users may visit those sites, triggering the embedded exploits.
If an exploit is successful, the attacker could execute arbitrary code with the privileges of the user. If that user holds elevated privileges, the attacker could execute arbitrary code to install malicious software or create additional user accounts on the system, resulting in a complete 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 user. If that user holds elevated privileges, the attacker could execute arbitrary code that could cause a complete system compromise.
Technical Information
The vulnerability is due to a flaw in Microsoft Office Web Components during the process of loading and unloading a control, 0002E543-0000-0000-C000-000000000046, which causes the control to be transferred to unallocated memory.
As a result, an unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious website that is designed to pass malicious input to the Office Web Components ActiveX control. The processing of the website could trigger an error condition that could allow the attacker to execute arbitrary code with the privileges of the user.
Safeguards
Administrators are advised to apply the appropriate software 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 necessary privileges.
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, 1:48 PM: Microsoft Office Web Components contain a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code with the privileges of the user. Updates are available.
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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