Microsoft Security Bulletin MS10-075 - Critical Vulnerability in Media Player Network Sharing Service Could Allow Remote Code Execution (2281679)

Microsoft Security Bulletin MS10-075 - Critical
Vulnerability in Media Player Network Sharing Service Could Allow Remote Code Execution (2281679)
Published: October 12, 2010

Version: 1.0
General Information
Executive Summary

This security update resolves a privately reported vulnerability in the Microsoft Windows Media Player Network Sharing Service. The vulnerability could allow remote code execution if an attacker sent a specially crafted RTSP packet to an affected system. However, Internet access to home media is disabled by default. In this default configuration, the vulnerability can be exploited only by an attacker within the same subnet.

This security update is rated Critical for supported editions of Windows 7 and Important for all supported editions of Windows Vista. 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 Windows Media Player Network Sharing Service handles specially crafted RTSP packets. 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. The majority of 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 immediately 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.

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
Operating System Maximum Security Impact Aggregate Severity Rating Bulletins Replaced by this Update

Windows Vista Service Pack 1 and Windows Vista Service Pack 2

Remote Code Execution

Important

None

Windows Vista x64 Edition Service Pack 1 and Windows Vista x64 Edition Service Pack 2

Remote Code Execution

Important

None

Windows 7 for 32-bit Systems

Remote Code Execution

Critical

None

Windows 7 for x64-based Systems

Remote Code Execution

Critical

None

Non-Affected Software
Operating System

Windows XP Service Pack 3

Windows XP Professional x64 Edition Service Pack 2

Windows Server 2003 Service Pack 2

Windows Server 2003 x64 Edition Service Pack 2

Windows Server 2003 with SP2 for Itanium-based Systems

Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2

Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2

Windows Server 2008 for Itanium-based Systems and Windows Server 2008 for Itanium-based Systems Service Pack 2

Windows Server 2008 R2 for x64-based Systems

Windows Server 2008 R2 for Itanium-based Systems
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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.

I am running an affected version of Microsoft Windows but the Windows Media Player Network Sharing Service is not started. Will I be offered this update?
Yes, the update will be offered to all systems running an affected Windows operating system regardless of whether or not the Windows Media Player Network Sharing Service is started.

Why is Windows Vista rated as Important and Windows 7 rated as Critical?
On Windows 7 Home Basic and Windows 7 Home Premium editions, the Media Player Network Sharing Service is enabled by default; therefore, the vulnerability is rated Critical. For Windows 7 Professional, Windows 7 Enterprise, and Windows 7 Ultimate editions, the service is not enabled by default.

For affected versions of Windows Vista, by default, the service is not enabled. This mitigating factor lowers the severity rating on supported editions of Windows Vista to Important.

How is the Windows 7 Service Pack 1 Beta release affected by this vulnerability?
Windows 7 Service Pack 1 Beta is affected by the vulnerability described in this bulletin. Customers running these beta releases are encouraged to download and apply the update to their systems. Security updates are available from Microsoft Update and Windows Update. The security update is also available for download from the Microsoft Download Center.

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 October bulletin summary. For more information, see Microsoft Exploitability Index.
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software RTSP Use After Free Vulnerability - CVE-2010-3225 Aggregate Severity Rating

Windows Vista Service Pack 1 and Windows Vista Service Pack 2

Important
Remote Code Execution

Important

Windows Vista x64 Edition Service Pack 1 and Windows Vista x64 Edition Service Pack 2

Important
Remote Code Execution

Important

Windows 7 for 32-bit Systems

Critical
Remote Code Execution

Critical

Windows 7 for x64-based Systems

Critical
Remote Code Execution

Critical
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RTSP Use After Free Vulnerability - CVE-2010-3225

A vulnerability exists in Microsoft Windows Media Player Network Sharing Service that could allow a remote user to send a specially crafted network packet to an instance of the application's network streaming service and cause remote code execution in the context of the current application.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-3225.

Mitigating Factors for RTSP Use After Free Vulnerability - CVE-2010-3225

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:
•

By default, Internet access to home media is disabled. In this default configuration, the vulnerability can be exploited only by computers within the same subnet.
•

On supported editions of Windows Vista and on Windows 7 Professional, Windows 7 Enterprise, and Windows 7 Ultimate editions, the Windows Media Player Network Sharing Service is not enabled by default.
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Workarounds for RTSP Use After Free Vulnerability - CVE-2010-3225

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:
•

Disable Windows Media Player Network Sharing Service on affected systems

Interactive Method

Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe.

Click Start, click Run, type Regedit in the Open box, and then click OK.

Locate and then select the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\WMPNetworkSvc

Click the File menu and then click Export.

In the Export Registry File dialog box, enter WMPNetworkSvc_Backup.reg and then click Save.

Note This will create a backup of this registry key in the My Documents folder by default.

Select the value Start on the right pane in the Registry Editor. Press Enter to edit the value of the key. Change the Value data field to 4, and press Enter.

From an elevated command prompt, stop the service by entering the following command:

sc stop WMPNetworkSvc

Managed Deployment Script

Make a backup copy of the registry key using the following command:

regedit /e WMPNetworkSvc_Backup.reg HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\WMPNetworkSvc

Save the following to a file with a .REG extension (e.g., Disable_WMPNetworkSvc.reg):

Windows Registry Editor Version 5.00
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\service_name]
Start"=dword:00000004

Run the registry script created in step 2 on the target machine with the following command:

Regedit /s Disable_WMPNetworkSvc.reg

From an elevated command prompt, stop the service by entering the following command:

sc stop WMPNetworkSvc

Impact of workaround. Windows Media Sharing will be disabled.

How to undo the workaround.

Using the interactive method:

Click Start, click Run, type Regedit in the Open box, and then click OK.

Click the File menu and then click Import.

In the Import Registry File dialog box, select the WMPNetworkSvc_Backup.regfile that was created in the "Interactive Method" above, and then click Open.

Exit Registry Editor, and then restart the computer.

Using the managed deployment script:

Run the registry script created in step 2 on the target machine with the following command:

Regedit /s WMPNetworkSvc_Backup.reg

Restart the computer.
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FAQ for RTSP use after free vulnerability - CVE-2010-3225

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could execute code in the security context of the Network Service account.

What causes the vulnerability?
The vulnerability is caused by the way that the Microsoft Windows Media Player Network Sharing Service processes Real Time Streaming Protocol (RTSP) packets.

How could an attacker exploit the vulnerability?
An attacker could exploit the vulnerability by creating and sending a specially crafted RTSP packet to an affected system.

What is RTSP?
The Real Time Streaming Protocol (RTSP) is an application-level protocol for control over the delivery of data with real-time properties. RTSP provides an extensible framework to enable controlled, on-demand delivery of real-time data, such as audio and video. Sources of data can include both live data feeds and stored clips. This protocol is intended to control multiple data delivery sessions, provide a means for choosing delivery channels such as UDP, multicast UDP and TCP, and provide a means for choosing delivery mechanisms based upon RTP (RFC 1889). RTSP is defined in RFC 2326.

RTSP supports player control actions such as stopping, pausing, rewinding, and fast-forwarding indexed Windows Media files. You can use RTSP to stream content to computers running Windows Media Player 9 Series or later or Windows Media Services 9 Series or later.

What is the Network Service account?
The Network Service account is a built-in account that has more access to resources and objects than members of the Users group. Services that run as the Network Service account access network resources by using the credentials of the computer account. The actual name of the account is NT AUTHORITY\NETWORK SERVICE. For more information, see the MSDN article, NetworkService Account.

What is Windows Media Player Network Sharing Service?
Windows Media Player lets you share files in your library with other users on your home network and to browse the files that are in libraries that other users on your network are sharing. Windows Media Sharing uses the Windows Media Player Network Sharing Service.

How can I determine if the Windows Media Player Network Sharing Service is running on my system?
Click Start, click Run, type Services.msc and then click OK. In the Services control panel, see whether the Windows Media Player Network Sharing Service has a status of "Started".

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take control of an affected system in the security context of the Network Service account.

What systems are primarily at risk from the vulnerability?
Systems running Windows Media Player Network Sharing Service (wmpnetwk.exe) to stream media are primarily at risk.

What does the update do?
The update addresses the vulnerability by correcting the way that Windows Media Player Network Sharing Service handles specially crafted RTSP packets.

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.

Other Information
Acknowledgments

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

Oleksandr Mirosh, working with TippingPoint's Zero Day Initiative, for reporting the RTSP use after free vulnerability (CVE-2010-3225)

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
•

V1.0 (October 12, 2010): Bulletin published.