Microsoft Office Excel contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system. Updates are available.
Description
Microsoft Office Excel contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system.
The vulnerability exists due to improper processing of malformed documents. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious document. If successful, the attacker could execute arbitrary code with the privileges of the user.
Microsoft has confirmed the vulnerability in a security bulletin and released software updates.
Warning Indicators
The following Microsoft Office applications are affected:
Microsoft Office Excel 2002 SP3 and prior
Microsoft Office Excel 2003 SP3 and prior
Microsoft Office 2004 for Mac
Microsoft Office 2008 for Mac
Open XML File Format Converter for Mac
IntelliShield Analysis
To exploit this vulnerability, an attacker must convince a user to view a malicious document. The attacker may provide documents to the user as e-mail attachments or by providing links within e-mail or instant messages that direct users to files hosted on remote file shares or websites. When opened, the document could trigger the execution of arbitrary code on the system with the privileges of the user.
The Cisco Applied Intelligence team has created an Applied Mitigation Bulletin to address vulnerabilities that Microsoft disclosed in the April 2011 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 April 2011
Vendor Announcements
Microsoft has released a security bulletin at the following link: MS11-021
Impact
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary code on the targeted system with the privileges of the user. If the user holds elevated privileges, a complete system compromise could occur.
Technical Information
The vulnerability exists due to errors in processing malformed Excel documents when managing data structures.
An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious document. The processing of the document could trigger an error, allowing the attacker to execute code with the privileges of the user.
Safeguards
Administrators are advised to apply the appropriate updates.
Users are advised not to open e-mail messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in e-mail messages are safe, they are advised not to open them.
Users may consider applying the Microsoft Office Isolated Conversion Environment (MOICE) to safely open Word, Excel, and PowerPoint 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.
Administrators are advised to monitor critical systems.
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
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