Additional technical information that describes the Microsoft Office Excel MDXSET record processing heap overflow vulnerability is available.
Microsoft Office Excel contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
The vulnerability exists due to insufficient validation of parameters within Excel documents when opening files in the application.† 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.
Microsoft Office Excel 2007 SP2 and prior and Office for Mac 2004 are affected.
An attacker cannot directly exploit this vulnerability and instead relies upon user participation to accomplish an exploit.† The attacker must persuade a user to open a malicious document, likely provided as an attachment to an e-mail message or posted on a public website.† The attacker may use social engineering techniques in an attempt to convince the user to open a provided document, possibly by making the document seem to originate from a trusted source.
If an exploit is successful, the attacker could execute arbitrary code with the privileges of the user.† Systems that restrict user privileges likely have reduced risk in the event of an exploit, as any code execution will occur in a limited security context.† Systems that grant users elevated privileges, such as membership in the Power Users or Administrator groups, could be at risk for complete compromise, as any executed code would run in an elevated security context.
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 Administrator privileges, the attacker could execute arbitrary code to take complete control over the system.
This vulnerability exists because the affected software does not perform boundary checks when processing the MDXSET records that are used to store metadata in Excel documents. During the processing of a document, a MDXSET record may be separated into multiple records. Values in the record are used to determine the size of memory buffers for storing parameter data from other record segments. The processing of a record designed to trigger the creation of a small memory buffer could cause a buffer overflow when large data is later copied into the buffer.
An unauthenticated, remote attacker could exploit the vulnerability by convincing a targeted user to view a malicious Microsoft Excel document that contains a malicious MDXSET record broken into several overly large records. The processing of the records could result in a heap-based buffer overflow that could corrupt memory. The attacker could take advantage of the memory corruption to execute arbitrary code on the targeted system with the privileges of the targeted 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 1, March 9, 2010, 1:37 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.
The security vulnerability applies to the following combinations of products.
2007 Base, SP1, SP2
Excel for Mac
2007 Base, SP1, SP2
Office for Mac
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