Additional technical information that describes the Microsoft Office Excel arbitrary code execution vulnerability is available.
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.
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
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.
Microsoft has released a security bulletin at the following link: MS10-017
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.
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.
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.
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 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.
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