Security Bulletin

Microsoft Security Bulletin MS12-053 - Critical

Vulnerability in Remote Desktop Could Allow Remote Code Execution (2723135)

Published: August 14, 2012 | Updated: October 10, 2012

Version: 2.1

General Information

Executive Summary

This security update resolves a privately reported vulnerability in the Remote Desktop Protocol. The vulnerability could allow remote code execution if an attacker sends a sequence of specially crafted RDP packets to an affected system. By default, the Remote Desktop Protocol (RDP) is not enabled on any Windows operating system. Systems that do not have RDP enabled are not at risk.

This security update is rated Critical for all supported editions of Windows XP. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by modifying the way that the Remote Desktop Protocol processes packets in memory. 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 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

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, see Microsoft Support Lifecycle.

Affected Software 

Non-Affected Software

Frequently Asked Questions (FAQ) Related to This Security Update

I have already successfully installed the original KB2723135 update. Do I need to apply the KB2723135 update packages rereleased on October 9, 2012?
No. The rereleased update only applies to Windows XP systems on which the original update has not been installed. Customers who have already successfully installed the original KB2723135 update on their Windows XP systems do not need to take any action. Customers will not be reoffered the update if it is already installed on their systems.

Why was this bulletin revised on October 9, 2012
Microsoft revised this bulletin to rerelease the KB2723135 update for Windows XP to address an issue involving specific digital certificates that were generated by Microsoft without proper timestamp attributes. For more information see Microsoft Security Advisory KB 2749655.

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.

Where are the hashes of the security updates? 
The SHA1 and SHA2 hashes of the security updates can be used to verify the authenticity of downloaded security update packages. For the hash information pertaining to this update, see Microsoft Knowledge Base Article 2723135.

I'm running an affected operating system, but I do not have Remote Desktop Protocol (RDP) enabled. Will I still be offered this update? 
Yes. Although systems that do not have RDP enabled are not at risk from the vulnerabilities, customers who have not enabled RDP will still be offered this update in order to help ensure the protection of their systems.

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

Remote Desktop Protocol Vulnerability - CVE-2012-2526

A remote code execution vulnerability exists in the way that the Remote Desktop Protocol accesses an object in memory after it has been deleted. An attacker who successfully exploited this vulnerability could run arbitrary code on the target system. 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-2012-2526.

Mitigating Factors for Remote Desktop Protocol Vulnerability - CVE-2012-2526

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, the Remote Desktop Protocol is not enabled on any Windows operating system. Systems that do not have RDP enabled are not at risk. Note that on Windows XP, Remote Assistance can enable RDP.
• Firewall best practices and standard default firewall configurations can help protect networks from attacks that originate outside the enterprise perimeter. Best practices recommend that systems connected directly to the Internet have a minimal number of ports exposed.

Workarounds for Remote Desktop Protocol Vulnerability - CVE-2012-2526

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:

• Block TCP port 3389 at the enterprise perimeter firewall

  TCP port 3389 is used to initiate a connection with the affected component. Blocking this port at the network perimeter firewall will help protect systems that are behind that firewall from attempts to exploit this vulnerability. This can help protect networks from attacks that originate outside the enterprise perimeter. Blocking the affected ports at the enterprise perimeter is the best defense to help avoid Internet-based attacks. However, systems could still be vulnerable to attacks from within their enterprise perimeter.

  On Windows XP, the Windows Firewall can help protect individual systems. By default, the Windows Firewall does not allow connections to this port, except in Windows XP Service Pack 2 and Windows XP Service Pack 3 when the Remote Desktop feature is enabled. For information about how to disable the Windows Firewall exception for Remote Desktop on these platforms, see the TechNet article, Enable or Disable the Remote Desktop Firewall Rule. If you cannot disable the Windows Firewall exception for Remote Desktop, you may be able to reduce the scope of this vulnerability by setting the default value of all computers (including those on the Internet), to the local network. Doing this helps reduce the likelihood of attacks from the Internet.

  Note It is possible to manually change the affected components to use other ports. If you have performed these actions, you should also block those additional ports.

• Disable Remote Desktop feature if no longer required

  If you no longer need these services on your system, consider disabling them as a security best practice. Disabling unused and unneeded services helps reduce your exposure to security vulnerabilities.

  For information about how to disable Remote Desktop manually, see To disable Remote Desktop.

  For information about how to disable Remote Desktop by using Group Policy, see Microsoft Knowledge Base Article 306300.

  For information about Remote Assistance, including instructions on how to disable Remote Assistance manually and by using Group Policy, see the TechNet article, Remote Assistance.

FAQ for Remote Desktop Protocol Vulnerability - CVE-2012-2526

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

What causes the vulnerability? 
The vulnerability is caused when the Remote Desktop Protocol processes a sequence of specially crafted packets, resulting in the access of an object in memory that has been deleted.

What is the Remote Desktop Protocol (RDP)? 
Remote Desktop Protocol (RDP) lets users create a virtual session on their desktop computers. RDP allows remote users to access all of the data and applications on their computers. For more information, see the MSDN article, Remote Desktop Protocol.

Is remote desktop enabled by default? 
No, RDP for administration is not enabled by default. However, customers who have not enabled RDP will still be offered this update in order to help ensure the protection of their systems.

What might an attacker use the vulnerability to do? 
An attacker who successfully exploited this vulnerability 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.

How could an attacker exploit the vulnerability? 
For systems running supported editions of Windows XP, a remote unauthenticated attacker could exploit this vulnerability by sending a sequence of specially crafted RDP packets to the target system.

What systems are primarily at risk from the vulnerability? 
Systems with RDP enabled are primarily at risk from this vulnerability. Systems that do not have RDP enabled are not at risk.

What does the update do? 
The update addresses the vulnerability by modifying the way that the Remote Desktop Protocol processes packets in memory.

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

Security Central

Manage the software and security updates you need to deploy to the servers, desktop, and mobile systems in your organization. For more information see the TechNet Update Management Center. The Microsoft TechNet Security website provides additional information about security in Microsoft products.

Security updates are available from Microsoft Update and Windows Update. Security updates are also available from the Microsoft Download Center. You can find them most easily by doing a keyword search for "security update."

Finally, security updates can be downloaded from the Microsoft Update Catalog. The Microsoft Update Catalog provides a searchable catalog of content made available through Windows Update and Microsoft Update, including security updates, drivers and service packs. By searching using the security bulletin number (such as, "MS12-001"), you can add all the applicable updates to your basket (including different languages for an update), and download to the folder of your choosing. For more information about the Microsoft Update Catalog, see the Microsoft Update Catalog FAQ.

Detection and Deployment Guidance

Microsoft provides detection and deployment guidance for security updates. This guidance contains recommendations and information that can help IT professionals understand how to use various tools for detection and deployment of security updates. For more information, see Microsoft Knowledge Base Article 961747.

Microsoft Baseline Security Analyzer

Microsoft Baseline Security Analyzer (MBSA) lets administrators scan local and remote systems for missing security updates as well as common security misconfigurations. For more information, see Microsoft Baseline Security Analyzer.

The following table provides the MBSA detection summary for this security update.

Note For customers using legacy software not supported by the latest release of MBSA, Microsoft Update, and Windows Server Update Services, please see Microsoft Baseline Security Analyzer and reference the Legacy Product Support section on how to create comprehensive security update detection with legacy tools.

Windows Server Update Services

Windows Server Update Services (WSUS) enables information technology administrators to deploy the latest Microsoft product updates to computers that are running the Windows operating system. For more information about how to deploy security updates using Windows Server Update Services, see the TechNet article, Windows Server Update Services.

Systems Management Server

The following table provides the SMS detection and deployment summary for this security update.

Note Microsoft discontinued support for SMS 2.0 on April 12, 2011. For SMS 2003, Microsoft also discontinued support for the Security Update Inventory Tool (SUIT) on April 12, 2011. Customers are encouraged to upgrade to System Center Configuration Manager. For customers remaining on SMS 2003 Service Pack 3, the Inventory Tool for Microsoft Updates (ITMU) is also an option.

For SMS 2003, the SMS 2003 Inventory Tool for Microsoft Updates (ITMU) can be used by SMS to detect security updates that are offered by Microsoft Update and that are supported by Windows Server Update Services. For more information about the SMS 2003 ITMU, see SMS 2003 Inventory Tool for Microsoft Updates. For more information about SMS scanning tools, see SMS 2003 Software Update Scanning Tools. See also Downloads for Systems Management Server 2003.

System Center Configuration Manager uses WSUS 3.0 for detection of updates. For more information, see System Center.

For more detailed information, see Microsoft Knowledge Base Article 910723: Summary list of monthly detection and deployment guidance articles.

Update Compatibility Evaluator and Application Compatibility Toolkit

Updates often write to the same files and registry settings required for your applications to run. This can trigger incompatibilities and increase the time it takes to deploy security updates. You can streamline testing and validating Windows updates against installed applications with the Update Compatibility Evaluator components included with Application Compatibility Toolkit.

The Application Compatibility Toolkit (ACT) contains the necessary tools and documentation to evaluate and mitigate application compatibility issues before deploying Windows Vista, a Windows Update, a Microsoft Security Update, or a new version of Windows Internet Explorer in your environment.

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. You can find additional information in the subsection, Deployment Information, in this section.

Deployment Information

Installing the Update

When you install this security update, the installer checks whether one or more of the files that are being updated on your system have previously been updated by a Microsoft hotfix.

If you have previously installed a hotfix to update one of these files, the installer copies the RTMQFE, SP1QFE, or SP2QFE files to your system. Otherwise, the installer copies the RTMGDR, SP1GDR, or SP2GDR files to your system. Security updates may not contain all variations of these files. For more information about this behavior, see Microsoft Knowledge Base Article 824994.

For more information about the installer, see Microsoft Knowledge Base Article 832475.

For more information about the terminology that appears in this bulletin, such as hotfix, see Microsoft Knowledge Base Article 824684.

This security update supports the following setup switches.

Note You can combine these switches into one command. For backward compatibility, the security update also supports the setup switches that the earlier version of the Setup program uses. For more information about the supported installation switches, see Microsoft Knowledge Base Article 262841.

Removing the Update

This security update supports the following setup switches.

Verifying That the Update Has Been Applied

• Microsoft Baseline Security Analyzer
  To verify that a security update has been applied to an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. See the section, Detection and Deployment Tools and Guidance, earlier in this bulletin for more information.

• File Version Verification
  Because there are several editions of Microsoft Windows, the following steps may be different on your system. If they are, see your product documentation to complete these steps.

  1. Click Start, and then click Search.
  2. In the Search Results pane, click All files and folders under Search Companion.
  3. In the All or part of the file name box, type a file name from the appropriate file information table, and then click Search.
  4. In the list of files, right-click a file name from the appropriate file information table, and then click Properties.
     Note Depending on the edition of the operating system, or the programs that are installed on your system, some files that are listed in the file information table may not be installed.
  5. On the Version tab, determine the version of the file that is installed on your system by comparing it to the version that is documented in the appropriate file information table.
     Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.

• Registry Key Verification
  You may also be able to verify the files that this security update has installed by reviewing the registry keys listed in the Reference Table in this section.

  These registry keys may not contain a complete list of installed files. Also, these registry keys may not be created correctly when an administrator or an OEM integrates or slipstreams this security update into the Windows installation source files.

Other Information

Acknowledgments

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

• Edward Torkington of NCC Group for reporting the Remote Desktop Protocol Vulnerability (CVE-2012-2526)

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 (August 14, 2012): Bulletin published.
• V2.0 (October 9, 2012): Revised bulletin to rerelease the KB2723135 update for Windows XP. Customers do not need to apply the rereleased update packages to avoid an issue with digital certificates described in Microsoft Security Advisory 2749655.
• V2.1 (October 10, 2012): For the rereleased KB2723135 update, added an FAQ entry to provide deployment guidance. See the update FAQ for details.

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