Microsoft Security Bulletin MS10-003 - Important Vulnerability in Microsoft Office (MSO) Could Allow Remote Code Execution (978214)

Microsoft Security Bulletin MS10-003 - Important
Vulnerability in Microsoft Office (MSO) Could Allow Remote Code Execution (978214)
Published: February 09, 2010

Version: 1.0
General Information
Executive Summary

This security update resolves a privately reported vulnerability in Microsoft Office that could allow remote code execution if a user opens a specially crafted Office file. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

This security update is rated Important for all supported editions of Microsoft Office XP and Microsoft Office 2004 for Mac. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The update addresses the vulnerability by modifying the way that Microsoft Office opens files. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.

Recommendation. Microsoft recommends that customers apply the update at the earliest opportunity.

Known Issues. None
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Affected and Non-Affected Software

The following software have been tested to determine which versions or editions are affected. Other versions or editions are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, visit Microsoft Support Lifecycle.

Affected Software
Office Suite and Other Software Maximum Security Impact Aggregate Severity Rating Bulletins Replaced by this Update
Microsoft Office Suites and Components

Microsoft Office XP Service Pack 3
(KB977896)

Remote Code Execution

Important

MS09-062
Microsoft Office for Mac

Microsoft Office 2004 for Mac
(KB979674)

Remote Code Execution

Important

None

Non-Affected Software
Office and Other Software

Microsoft Office 2003 Service Pack 3

2007 Microsoft Office System Service Pack 1

2007 Microsoft Office System Service Pack 2

Microsoft Office 2008 for Mac

Open XML File Format Converter for Mac

Microsoft Office Excel Viewer Service Pack 1 and Microsoft Office Excel Viewer Service Pack 2

Microsoft Office Word Viewer

PowerPoint Viewer 2007 Service Pack 1 and PowerPoint Viewer 2007 Service Pack 2

Visio Viewer 2007 Service Pack 1 and Visio Viewer 2007 Service Pack 2

Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats Service Pack 1 and Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats Service Pack 2

Microsoft Works 8.5

Microsoft Works 9
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Frequently Asked Questions (FAQ) Related to This Security Update

Where are the file information details?
Refer to the reference tables in the Security Update Deployment section for the location of the file information details.

MS10-004 also describes a vulnerability in Microsoft Office 2004 for Mac. How does MS10-004 Relate to this bulletin (MS10-003)?
As part of the cumulative servicing model for Microsoft Office 2004 for Mac, this security update for Microsoft Office 2004 for Mac (KB979674) also addresses the vulnerabilities described in MS10-004. Users with Microsoft Office 2004 for Mac installed will have to install this security update but will only need to install it once.

I am using an older release of the software discussed in this security bulletin. What should I do?
The affected software listed in this bulletin have been tested to determine which releases are affected. Other releases are past their support life cycle. For more information about the product lifecycle, visit the Microsoft Support Lifecycle Web site.

It should be a priority for customers who have older releases of the software to migrate to supported releases to prevent potential exposure to vulnerabilities. To determine the support lifecycle for your software release, see Select a Product for Lifecycle Information. For more information about service packs for these software releases, see Lifecycle Supported Service Packs.

Customers who require custom support for older software must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers without an Alliance, Premier, or Authorized Contract can contact their local Microsoft sales office. For contact information, visit the Microsoft Worldwide Information Web site, select the country in the Contact Information list, and then click Go to see a list of telephone numbers. When you call, ask to speak with the local Premier Support sales manager. For more information, see the Microsoft Support Lifecycle Policy FAQ.
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Vulnerability Information

Severity Ratings and Vulnerability Identifiers

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the February bulletin summary. For more information, see Microsoft Exploitability Index.
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software MSO.DLL Buffer Overflow - CVE-2010-0243 Aggregate Severity Rating
Microsoft Office Suites and Components

Microsoft Office XP Service Pack 3

Important
Remote Code Execution

Important
Microsoft Office for Mac

Microsoft Office 2004 for Mac

Important
Remote Code Execution

Important
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MSO.DLL Buffer Overflow - CVE-2010-0243

A remote code execution vulnerability exists in the way Microsoft Office handles specially crafted Office files. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-0243.

Mitigating Factors for MSO.DLL Buffer Overflow - CVE-2010-0243

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:
•

An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
•

The vulnerability cannot be exploited automatically through e-mail. For an attack to be successful, a user must open an attachment that is sent in an e-mail message.
•

In a Web-based attack scenario, an attacker could host a Web site that contains an Office file that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or Instant Messenger message that takes users to the attacker's Web site, and then convince the users to open a specially crafted Office file.
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Workarounds for MSO.DLL Buffer Overflow - CVE-2010-0243

Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:
•

Do not open Office files from untrusted sources

Do not open Microsoft Office files that you receive from untrusted sources or that you receive unexpectedly from trusted sources. This vulnerability could be exploited when a user opens a specially crafted file
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FAQ for MSO.DLL Buffer Overflow - CVE-2010-0243

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

What causes the vulnerability?
When a user opens a specially crafted Office file, it may corrupt system memory in such a way that an attacker could execute arbitrary code.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could run arbitrary code as the logged-on user. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. If a user is logged-on with administrative user rights, an attacker could take complete control of the affected system. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

How could an attacker exploit the vulnerability?
This vulnerability requires that a user open a specially crafted Office file with an affected version of the software.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted Office file to the user and by convincing the user to open the file.

In a Web-based attack scenario, a Web site could contain an Office file that is used to exploit this vulnerability. An attacker would have to convince users to visit the Web site and open a specially crafted Office file, typically by getting them to click a link in an e-mail message or Instant Messenger message that takes users to the attacker's Web site.

What systems are primarily at risk from the vulnerability?
Systems where the affected products are used, including workstations and terminal servers, are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

What does the update do?
The update addresses the vulnerability by modifying the way that Microsoft Office opens files.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

Other Information
Acknowledgments

Microsoft thanks the following for working with us to help protect customers:
•

Damian Frizza of Core Security Technologies for reporting the MSO.DLL Buffer Overflow Vulnerability (CVE-2010-0243)
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Microsoft Active Protections Program (MAPP)

To improve security protections for customers, Microsoft provides vulnerability information to major security software providers in advance of each monthly security update release. Security software providers can then use this vulnerability information to provide updated protections to customers via their security software or devices, such as antivirus, network-based intrusion detection systems, or host-based intrusion prevention systems. To determine whether active protections are available from security software providers, please visit the active protections Web sites provided by program partners, listed in Microsoft Active Protections Program (MAPP) Partners.

Support
•

Customers in the U.S. and Canada can receive technical support from Security Support or 1-866-PCSAFETY. There is no charge for support calls that are associated with security updates. For more information about available support options, see Microsoft Help and Support.
•

International customers can receive support from their local Microsoft subsidiaries. There is no charge for support that is associated with security updates. For more information about how to contact Microsoft for support issues, visit the International Support Web site.

Disclaimer

The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.

Revisions
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V1.0 (February 9, 2010): Bulletin published.