Security Bulletin

Microsoft Security Bulletin MS13-051 - Important

Vulnerability in Microsoft Office Could Allow Remote Code Execution (2839571)

Published: June 11, 2013

Version: 1.0

General Information

Executive Summary

This security update resolves one privately reported vulnerability in Microsoft Office. The vulnerability could allow remote code execution if a user opens a specially crafted Office document using an affected version of Microsoft Office software, or previews or opens a specially crafted email message in Outlook while using Microsoft Word as the email reader. An attacker who successfully exploited this vulnerability could gain the same user rights as the current 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.

This security update is rated Important for supported editions of Microsoft Office 2003 and Microsoft Office for Mac 2011. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by correcting the way that Microsoft Office parses specially crafted Office 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. Customers can configure automatic updating to check online for updates from Microsoft Update by using the Microsoft Update service. Customers who have automatic updating enabled and configured to check online for updates from Microsoft Update typically will not need to take any action because this security update will be downloaded and installed automatically. Customers who have not enabled automatic updating need to check for updates from Microsoft Update and install this update manually. For information about specific configuration options in automatic updating, see Microsoft Knowledge Base Article 294871.

For administrators and enterprise installations, or end users who want to install this security update manually, Microsoft recommends that customers apply the update at the earliest opportunity using update management software, or by checking for updates using the Microsoft Update service.

For customers of Microsoft Office for Mac, Microsoft AutoUpdate for Mac can be configured to deliver updates for Microsoft software directly to your system. For more information, see Check for Office for Mac updates automatically.

See also the section, Detection and Deployment Tools and Guidance, later in this bulletin.

Knowledge Base Article

Affected and Non-Affected Software

The following software has 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, see Microsoft Support Lifecycle.

Affected Software

Non-Affected Software 

Update FAQ

How is Microsoft Office 2003 software affected by the vulnerability ? 
Because the vulnerable code exists in a shared component of Microsoft Office 2003, the update for Microsoft Office 2003 Service Pack 3 (2817421) may be offered to both affected and non-affected software. The 2817421 update applies to the following Microsoft Office 2003 software that is affected by the vulnerability:

• Microsoft Excel 2003 Service Pack 3
• Microsoft InfoPath 2003 Service Pack 3
• Microsoft OneNote 2003 Service Pack 3
• Microsoft Outlook 2003 Service Pack 3
• Microsoft PowerPoint 2003 Service Pack 3
• Microsoft Publisher 2003 Service Pack 3
• Microsoft Word 2003 Service Pack 3
• Microsoft Word Viewer

The 2817421 update applies to Microsoft Outlook 2003 as specified above. However, Outlook is only affected by the vulnerability if Word is the selected email reader. An attacker could leverage Outlook for an email attack vector to exploit the vulnerability by sending a specially crafted email message to the target user. The vulnerability could be exploited when a user previews or opens the specially crafted email message in Outlook while using Microsoft Word as the email reader. Note that by default, Microsoft Word is not the email reader in Outlook 2003.

For other software, you may be offered the 2817421 update even though you do not have affected Microsoft Office 2003 software installed, if you have software that contains the vulnerable shared component of Microsoft Office 2003. Note that because the software does not access the vulnerable code, the software is not affected by the vulnerability. However, since the vulnerable code is present, this update will be offered.

Does the offer to update a non-vulnerable version of Microsoft Office software constitute an issue in the Microsoft update mechanism? 
No. The update mechanism is functioning correctly in that it detects a product version for the applicable software on the system that is within the range of product versions that the update applies to and thus, offers the update.

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 has been tested to determine which releases are affected. Other releases are past their support life cycle. For more information about the product lifecycle, see the Microsoft Support Lifecycle website.

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 Service Pack Lifecycle Support Policy.

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, see the Microsoft Worldwide Information website, 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.

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 June bulletin summary. For more information, see Microsoft Exploitability Index.

Office Buffer Overflow Vulnerability - CVE-2013-1331

A remote code execution vulnerability exists in the way that Microsoft Office parses 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-2013-1331.

Mitigating Factors

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:

• In a web-based attack scenario, an attacker could host a website that contains a specially crafted Office file that is used to attempt to exploit this vulnerability. In addition, compromised websites and websites 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 websites. Instead, an attacker would have to convince users to visit the website, typically by getting them to click a link in an email message or Instant Messenger message that takes users to the attacker’s website, and convince them to open the specially crafted Office file.
• An attacker who successfully exploited this vulnerability could gain the same user rights as the current 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.

Workarounds

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 that you receive from untrusted sources or that you receive unexpectedly from trusted sources
  Do not open 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.

• For Microsoft Office for Mac 2011, disassociate binary Office file formats from Office for Mac in OS X's LaunchServices database
  Note This workaround prevents Office files from being automatically opened through file format association. However, users are still vulnerable if they choose to manually open malicious Office files from within an Office application.

  Use this workaround to prevent Microsoft Office for Mac from opening binary Office files directly and to designate the Finder as the default method for opening binary Office files. These include the following file formats:

  .doc, .dot, .docm, .dotm, .ppt, .pot, .pps, .pptm, .potm, .ppsm, .xls, .xlt, .xlsb, .xlsm, .xltm

  To do this, open the Finder and perform these steps for each binary Office file format listed:

  1. Select the binary Office file format you want to disassociate and press Command-I to open the Info dialog box.
  2. In the Open With section, select Other from the menu.
  3. In the Open dialog window that appears, select All Applications from the Enable menu.
  4. Navigate to the Macintosh HD > System > Library > CoreServices folder and select the Finder.
  5. Click the Change All button in the Info window to make the Finder the default program for opening all files in the selected file format. When you attempt to open Office files, the Finder will appear and you can choose to open the Office file.
     Repeat these steps for each binary Office file format.

  Note You will need to re-apply this workaround if you clean your LaunchServices database. Cleaning the LaunchServices database removes your customizations and resets the values from the applications info.plist.

  Impact of Workaround Office files will no longer automatically open through file format association.

FAQ

What is the scope of the vulnerability? 
This is a remote code execution vulnerability.

What causes the vulnerability? 
The vulnerability is caused when Microsoft Office components for processing PNG files do not properly handle memory allocation. System memory may be corrupted 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 in the context of the current user. If the current user is logged on with administrative user rights, an attacker could take complete control of the 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.

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

In an email attack scenario, an attacker could exploit the vulnerability by sending specially crafted Office data in the contents of an email message. The vulnerability could be exploited when the specially crafted email message is previewed or opened in Outlook while using Microsoft Word as the email reader. Note that by default, Microsoft Word is not the email reader in Outlook 2003. An attacker could also exploit the vulnerability by sending a specially crafted Office file to the user, and then by convincing the user to open the file with an affected version of Microsoft Office software.

In a web-based attack scenario, an attacker would have to host a website that contains an Office file that is used to attempt to exploit this vulnerability. In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit a specially crafted website. Instead, an attacker would have to convince them to visit the website, typically by getting them to click a link in an email message or Instant Messenger message that takes them to the attacker's site, and then convince them to open the specially crafted Office file.

What systems are primarily at risk from the vulnerability? 
Systems where affected Microsoft Office software is 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.

For more information about which Microsoft Office 2003 software is at risk from the vulnerability, see "How is Microsoft Office 2003 software affected by the vulnerability?" in the Update FAQ section.

Does EMET help mitigate attacks that try to exploit this vulnerability? 
Yes. The Enhanced Mitigation Experience Toolkit (EMET) enables users to manage security mitigation technologies that help make it more difficult for attackers to exploit vulnerabilities in a given piece of software. EMET helps to mitigate this vulnerability in Microsoft Office on systems where EMET is installed and configured to work with the affected Microsoft Office software.

For more information about EMET, see The Enhanced Mitigation Experience Toolkit.

What does the update do? 
This update addresses the vulnerability by correcting the way that Microsoft Office parses specially crafted Office files.

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

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited? 
Yes. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability.

Update Information

Detection and Deployment Tools and Guidance

Several resources are available to help administrators deploy security updates. 

• Microsoft Baseline Security Analyzer (MBSA) lets administrators scan local and remote systems for missing security updates and common security misconfigurations. 
• Windows Server Update Services (WSUS), Systems Management Server (SMS), and System Center Configuration Manager (SCCM) help administrators distribute security updates. 
• The Update Compatibility Evaluator components included with Application Compatibility Toolkit aid in streamlining the testing and validation of Windows updates against installed applications. 

For more information about these tools and guidance in deploying security updates across networks, see Security Tools for IT Pros. 

For customers of Microsoft Office for Mac, Microsoft AutoUpdate for Mac can help keep your Microsoft software up to date. For more information, see Check for Office for Mac updates automatically.

Security Update Deployment

Affected Software

For information about the specific security update for your affected software, click the appropriate link:

Microsoft Office 2003 (all editions)

Reference Table

The following table contains the security update information for this software.

Office for Mac 2011

Prerequisites

• Mac OS X version 10.5.8 or later version on an Intel processor
• Mac OS X user accounts must have administrator privileges to install this security update

Installing the Update

Download and install the appropriate language version of the Microsoft Office for Mac 2011 14.3.5 Update from the Microsoft Download Center.

• Quit any applications that are running, including virus-protection applications and all Microsoft Office applications, because they might interfere with installation.
• Open the Microsoft Office for Mac 2011 14.3.5 Update volume on your desktop. This step might have been performed for you.
• To start the update process, in the Microsoft Office for Mac 2011 14.3.5 Update volume window, double-click the Microsoft Office for Mac 2011 14.3.5 Update application, and follow the instructions on the screen.
• When the installation finishes successfully, you can remove the update installer from your hard disk. To verify that the installation finished successfully, see the following "Verifying Update Installation" heading. To remove the update installer, first drag the Microsoft Office for Mac 2011 14.3.5 Update volume to the Trash, and then drag the file that you downloaded to the Trash.

Verifying Update Installation

To verify that a security update is installed on an affected system, follow these steps:

1. In the Finder, navigate to the Application Folder (Microsoft Office 2011).
2. Select Word, Excel, PowerPoint or Outlook and launch the application.
3. On the Application menu, click About Application_Name (where Application_Name is Word, Excel, PowerPoint or Outlook).

If the Latest Installed Update Version number is 14.3.5, the update has been successfully installed.

Restart Requirement

This update does not require you to restart your computer.

Removing the Update

This security update cannot be uninstalled.

Additional Information

If you have technical questions or problems downloading or using this update, see Microsoft for Mac Support to learn about the support options that are available to you.

Other Information

Acknowledgments

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

• Andrew Lyons and Neel Mehta of Google Inc for reporting the Office Buffer Overflow Vulnerability (CVE-2013-1331)

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 go to the active protections websites provided by program partners, listed in Microsoft Active Protections Program (MAPP) Partners.

Support

How to obtain help and support for this security update

• Help installing updates: Support for Microsoft Update
• Security solutions for IT professionals: TechNet Security Troubleshooting and Support
• Help protect your computer that is running Windows from viruses and malware: Virus Solution and Security Center
• Local support according to your country: International Support

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

• V1.0 (June 11, 2013): Bulletin published.

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