Functional code that exploits the Microsoft Office Excel Featheader record processing arbitrary code execution vulnerability is available.
Microsoft Office Excel contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
This vulnerability exists due to errors in processing Featheader records during the opening of Excel documents. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious file. If the user opens the file, the attacker could execute arbitrary code on the system with the privileges of the user.
Functional code that exploits this vulnerability is circulating in the wild as part of malware distributed through spam e-mail messages.
Microsoft has confirmed this vulnerability in a security bulletin and released software updates.
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 2003 SP3 and prior
Office Excel Viewer 2007 SP2 and prior
Office 2004 for Mac
Office 2008 for Mac
Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP2 and prior
An attacker cannot directly exploit this vulnerability and instead must rely upon user interaction in order to accomplish an exploit. The attacker must convince the user to open a malicious document on the vulnerable system. The attacker may send documents to users via e-mail messages or post documents on public websites. Attackers may use social engineering techniques in an attempt to convince a user to open a provided document.
If an exploit is successful, the attacker could execute arbitrary code with the privileges of the user. Systems that restrict user privileges may have little impact in the event of an exploit, as any code execution would occur with limited privileges. However, on systems that grant users elevated privileges, the attacker could completely compromise the system, as any executed code may run in a privileged security context.
Microsoft has released a security bulletin at the following link: MS09-067
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 code resulting in a complete system compromise.
The vulnerability is due to errors when the vulnerable application handles Featheader tags that are used in Excel Binary Interchange File Format (BIFF) files. An unauthenticated, remote attacker could exploit this vulnerability by crafting an Excel document that contains malicious values for the cbHdrData element within Featheader tags and convincing a user to open the document. Errors that occur when processing the file in Excel could allow the attacker to execute arbitrary code with privileges of the user.
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 privileges possible.
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.
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.
Version 2, November 11, 2009, 10:44 AM: Additional technical information is available to describe the Microsoft Office Excel Featheader record processing arbitrary code execution vulnerability.
Version 1, November 10, 2009, 1:58 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.
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