Security Bulletin

Microsoft Security Bulletin MS13-102 - Important

Vulnerability in LRPC Client Could Allow Elevation of Privilege (2898715)

Published: December 10, 2013

Version: 1.0

General Information

Executive Summary

This security update resolves a privately reported vulnerability in Microsoft Windows. The vulnerability could allow elevation of privilege if an attacker spoofs an LRPC server and sends a specially crafted LPC port message to any LRPC client. An attacker who successfully exploited the vulnerability could then install programs; view, change, or delete data; or create new accounts with full administrator rights. An attacker must have valid logon credentials and be able to log on locally to exploit this vulnerability.

This security update is rated Important for all supported editions of Windows XP and Windows Server 2003. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by validating LRPC messages. 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 

** **

Non-Affected Software

Update FAQ

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

LRPC Client Buffer Overrun Vulnerability - CVE-2013-3878

An elevation of privilege vulnerability exists in Microsoft Local Remote Procedure Call (LRPC) where an attacker spoofs an LRPC Server and uses a specially crafted LPC port message to cause a stack-based buffer overflow condition on the LRPC client. LRPC internally uses Microsoft Local Procedure Call (LPC). So, in effect, any LPC consumer might be impacted by this vulnerability, if not properly implemented. An attacker who successfully exploited this vulnerability could then install programs; view, change, or delete data; or create new accounts with full administrator rights.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2013-3878.

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:

• An attacker must have valid logon credentials and be able to log on locally to exploit this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

FAQ

What is the scope of the vulnerability?
This is an elevation of privilege vulnerability.

What causes the vulnerability?
This vulnerability is caused when a stack-based buffer overflow condition occurs during the exchange of port messages between any LPC client and LPC server.

What is the component affected by the vulnerability?
The component affected by the vulnerability is Local RPC (LRPC), a component of Microsoft Remote Procedure Call (RPC). LRPC internally uses Microsoft Local Inter-Process Communication (LPC). Any LPC consumer could be impacted by this vulnerability if not properly implemented.

What is LPC? Local Inter-Process Communication (LPC) is an Inter-Process Communication (IPC) service in Microsoft Windows. This service allows threads and processes to communicate with each other. When the client process and the server process are located on the same system, LPC can be used. Beginning with Windows Vista, the use of LPC was deprecated by a newer mechanism called Asynchronous LPC (ALPC). Note that Microsoft does not recommend the use of LPC/ALPC directly. Applications should instead use the supported framework, LRPC, which internally uses LPC/ALPC.

What is RPC? Remote Procedure Call (RPC) is an Inter-Process Communication (IPC) mechanism that enables data exchange and invocation of functionality residing in a different process. That process can be on the same computer, on the local area network (LAN), or across the Internet. The Microsoft RPC mechanism uses other IPC mechanisms, such as named pipes, NetBIOS, or Winsock, to establish communications between the client and the server. With RPC, essential program logic and related procedure code can exist on different computers, which is important for distributed applications. For more information, see the TechNet article, What Is RPC?

What is LRPC? Local RPC (LRPC) is an Inter-Process Communication (IPC) mechanism that enables data exchange and invocation of functionality residing in a different process that resides on the same computer. LRPC is a component of Microsoft RPC. LRPC internally uses LPC as the transport mechanism for passing messages between the two processes.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could elevate their privileges on the local system. The attacker could then install programs; view, change, or delete data; or create new accounts with full administrator rights.

How could an attacker exploit the vulnerability?
An attacker who is able to log on locally with valid credentials could exploit the vulnerability by running a specially crafted LRPC server that sends a specially crafted LPC port message to the LRPC client. If the message size exceeds defined limits, the resulting memory corruption condition could allow elevation of the attacker's privileges on the local system.

What systems are primarily at risk from the vulnerability?
Workstations and terminal servers are primarily at risk. Servers could be at more risk if users who do not have sufficient administrative permissions are given the ability 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 validating LRPC messages.

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.

Other Information

Acknowledgments

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

• Renguang Yuan of Qihoo for reporting the LRPC Client Buffer Overrun Vulnerability (CVE-2013-3878)

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 (December 10, 2013): Bulletin published.

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