Security Bulletin

Microsoft Security Bulletin MS13-071 - Important

Vulnerability in Windows Theme File Could Allow Remote Code Execution (2864063)

Published: September 10, 2013

Version: 1.0

General Information

Executive Summary

This security update resolves a privately reported vulnerability in Microsoft Windows. The vulnerability could allow remote code execution if a user applies a specially crafted Windows theme on their system. In all cases, a user cannot be forced to open the file or apply the theme; for an attack to be successful, a user must be convinced to do so.

This security update is rated Important for all supported editions of Windows XP and Windows Server 2003. For supported editions of Windows Vista and Windows Server 2008, this secuirty update as no severity rating. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by changing how Windows handles theme files and screensavers. 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. Most customers have automatic updating enabled and 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 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.

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 

^[1]Severity ratings do not apply to this update for the specified software because the known attack vectors for the vulnerability discussed in this bulletin are blocked in a default configuration. However, as a defense-in-depth measure, Microsoft recommends that customers of this software apply this security update.

Non-Affected Software

Update FAQ

After installing the update, when I apply a custom theme, the associated screensaver is not automatically selected. Instead, the Screen saver selection is set to "Blank". How can I apply the screensaver associated with my custom theme?
With this update, screen savers associated with custom themes that were not delivered in-box are not automatically selected when a custom theme is applied. This behavior was designed into the update to help make your system more secure. If you want to apply a custom screen saver that is known to be secure, right-click the .scr file and select Install, or use Group Policy to apply the screen saver selection on multiple systems.

What is defense-in-depth?
In information security, defense-in-depth refers to an approach in which multiple layers of defense are in place to help prevent attackers from compromising the security of a network or system.

How are Server Core installations affected by the vulnerability addressed in this bulletin?
The vulnerability addressed by this update do not affect supported editions of Windows Server 2008, Windows Server 2008 R2, or Windows Server 2012 as indicated in the Non-Affected Software table, when installed using the Server Core installation option. For more information on this installation option, see the TechNet articles, Managing a Server Core Installation: Overview, Servicing a Server Core Installation, and Server Core and Full Server Integration Overview.

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 vulnerability. 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 September bulletin summary. For more information, see Microsoft Exploitability Index.

^[1]Severity ratings do not apply to this update for the specified software because the known attack vectors for the vulnerability discussed in this bulletin are blocked in a default configuration. However, as a defense-in-depth measure, Microsoft recommends that customers of this software apply this security update.

Windows Theme File Remote Code Execution Vulnerability - CVE-2013-0810

A remote code execution vulnerability exists in the way that affected editions of Microsoft Windows handles certain specially crafted Windows theme files. This vulnerability could allow an attacker to execute arbitrary code if the attacker convinces a user to apply a specially crafted Windows theme. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2013-0810.

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 all cases, a user cannot be forced to open the file or apply the theme; for an attack to be successful, a user must be convinced to do so.

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 Windows theme 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.

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 Windows improperly handles theme and screensaver files.

What is a Windows theme?
In Microsoft Windows, themes are a combination of personalization settings that change how your desktop looks and sounds. Themes can simultaneously change the desktop background, window border color, sounds, and screen saver on your Windows PC. Users can switch between themes and can create, and share, personalized themes.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could run arbitrary code as the current user. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. If the current 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?
In an attack scenario, an attacker could convince a user to open a specially crafted theme file containing a specially crafted screensaver that executes arbitrary code when the user applies the Windows theme.

What systems are primarily at risk from the vulnerability?
Workstations are primarily at risk from this vulnerability.

What does the update do?
The update addresses the vulnerability by changing how Windows handles theme files and screensavers.

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?
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.

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 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 information about these and other tools that are available, see Security Tools for IT Pros. 

Security Update Deployment

Affected Software

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

Windows XP (all editions)

Reference Table

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

Note The update for supported versions of Windows XP Professional x64 Edition also applies to supported versions of Windows Server 2003 x64 Edition.

Windows Server 2003 (all editions)

Reference Table

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

Note The update for supported versions of Windows Server 2003 x64 Edition also applies to supported versions of Windows XP Professional x64 Edition.

Windows Vista (all editions)

Reference Table

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

Windows Server 2008 (all editions)

Reference Table

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

Other Information

Acknowledgments

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

• Eduardo Prado, working with VeriSign iDefense Labs, for reporting the Windows Theme File Remote Code Execution Vulnerability (CVE-2013-0810)

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 (September 10, 2013): Bulletin published.

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