Proof-of-concept code that exploits the Microsoft Office web components buffer overflow vulnerability is publicly available.
Description
Microsoft Office Web Components contain a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
This vulnerability exists due to errors in processing malformed data by the Office Web Components ActiveX control. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious website. If successful, the attacker could execute arbitrary code with the privileges of the user.
Proof-of-concept code that exploits this vulnerability is publicly available.
Microsoft has confirmed this vulnerability in a security bulletin and released software updates that correct it.
Warning Indicators
The following applications are vulnerable:
Microsoft Office XP SP3 and prior
Microsoft Office 2000 Web Components SP3 and prior
Microsoft Office XP Web Components SP3 and prior
Microsoft BizTalk Server 2002 and prior
Microsoft Visual Studio .NET 2003 SP1 and prior
IntelliShield Analysis
In order to exploit this vulnerability, an attacker must convince a user to view a malicious website. Attackers may attempt to embed malicious content within public websites and direct users to those sites via e-mailed links. The attacker may also use social engineering techniques in an attempt to convince users that sites or e-mail messages originate from known, trusted sources.
If an exploit is successful, the attacker could execute arbitrary code with the privileges of the user. End-host systems on which users hold Administrator privileges are most at risk, as an exploit where the users holds elevated privileges could allow the attacker to gain complete control over the system.
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 Administrator privileges, the attacker could execute arbitrary code to gain complete control over the system.
Technical Information
This vulnerability exists due to errors in processing malformed data by the Office Web Components ActiveX control. The processing of overly large data could trigger a buffer overflow, corrupting system memory. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious website designed to send malformed data to the vulnerable ActiveX control. The processing of the data could cause memory corruption, which the attacker could leverage to execute arbitrary code with the privileges of the user.
Safeguards
Administrators are advised to apply the applicable 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 2, August 17, 2009, 1:47 PM: The Applied Mitigations Bulletin Link has been corrected for the Microsoft Office web components buffer overflow vulnerability
Version 1, August 11, 2009, 1:56 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.
BizTalk Server
2002 Base
Microsoft, Inc.
Office
XP (2002) Base, SP1, SP2, SP3
Microsoft, Inc.
Office Web Components (OWC)
10 (Office XP) Base | 9 (Office 2000) Base
Microsoft, Inc.
Visual Studio
.NET 2003 Base, SP1
Associated Products:
N/A
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