Microsoft Office Excel contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
This vulnerability exists due to errors in parsing malformed formula data contained within Excel document cell fields. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious file. If the user views the file, the attacker could execute arbitrary code on the system with the privileges of the user.
Microsoft has confirmed this vulnerability in a security bulletin and released software updates.
Indicators of Compromise
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
This vulnerability exists due to errors in parsing malformed formula data contained within Excel document cell fields. An unauthenticated, remote attacker could exploit this vulnerability by creating a malicious document and then convincing a user to view the document. When opened, the document could cause memory corruption that the attacker could leverage to execute arbitrary code with the privileges of the user.
An attacker cannot directly exploit this vulnerability and instead must convince a user to view a malicious document in order to accomplish an exploit. If successful, the attacker could execute code with the privileges of the user. An attacker would have to deliver a document to the user prior to an exploit, likely by sending it as an e-mail attachment or by posting it publicly on a remote website.
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 has released a security bulletin at the following link: MS09-067
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.
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Cisco Multivendor Vulnerability Alerts respond to vulnerabilities identified in third-party vendors' products. These alerts contain information compiled from diverse sources and provide comprehensive technical descriptions, objective analytical assessments, workarounds and practical safeguards, and links to vendor advisories and patches.