Microsoft Security Bulletin MS14-047 - Important

• 10/11/2017
• 14 minutes to read
• • 

Vulnerability in LRPC Could Allow Security Feature Bypass (2978668)

Published: August 12, 2014

Version: 1.0

General Information

Executive Summary

This security update resolves a privately reported vulnerability in Microsoft Windows. The vulnerability could allow security feature bypass if an attacker uses the vulnerability in conjunction with another vulnerability, such as a remote code execution vulnerability, that takes advantage of the ASLR bypass to run arbitrary code.

This security update is rated Important for all supported editions of Windows 7, Windows Server 2008 R2, Windows 8, Windows 8.1, Windows Server 2012, Windows Server 2012 R2, Windows RT, and Windows RT 8.1. For more information, see the Affected and Non-Affected Software section.

The security update addresses the vulnerability by correcting how RPC handles the freeing of malformed messages. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability later in this bulletin.

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. For information about specific configuration options in automatic updating, see Microsoft Knowledge Base Article 294871. For customers who do not have automatic updating enabled, the steps in Turn automatic updating on or off can be used to enable automatic updating.

For administrators and enterprise installations, or end users who want to install this security update manually (including customers who have not enabled automatic updating), 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. The updates are also available via the download links in the Affected Software table later in this bulletin.

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

Knowledge Base Article

• Knowledge Base Article: 2978668
• File Information: Yes
• SHA1/SHA2 hashes: Yes
• Known issues: None

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 

^[2]This update is available via Windows Update.

Non-Affected Software

LRPC ASLR Bypass Vulnerability - CVE-2014-0316

A security feature bypass vulnerability exists in Microsoft Remote Procedure Call (LRPC). The problem is that an LRPC server may leak the message it receives from the client if the message is of a specific type and has a data view attached (which is not expected for messages of the type). RPC considers this an error and returns, but does not free the message. This allows the client to fill up the address space of the server with such messages.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2014-0316.

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

FAQ

What is the scope of the vulnerability?
This is a security feature bypass vulnerability.

What causes the vulnerability?
The vulnerability is caused when RPC improperly frees messages that the server rejects as malformed, allowing an attacker to fill up the address space of a process.

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).

What is Remote Procedure Call (RPC)?
Microsoft Remote Procedure Call (RPC) is an interprocess communications (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 What Is RPC?

What is LRPC?
Local RPC (LRPC) is a component of Microsoft RPC. LRPC internally uses LPC as the transport mechanism for passing messages between the two processes.

What are Interprocess Communications (IPC)?
Microsoft Windows operating systems provide mechanisms for facilitating communications and data sharing between applications. Collectively, the activities enabled by these mechanisms are called interprocess communications (IPC). Some forms of IPC facilitate the division of labor among several specialized processes. Other forms of IPC facilitate the division of labor among computers on a network. For more information, see Interprocess Communications.

What might an attacker use the vulnerability to do?
In a web-browsing attack scenario, an attacker who successfully exploited this vulnerability could bypass the ASLR security feature, which protects users from a broad class of vulnerabilities. The security feature bypass by itself does not allow arbitrary code execution. However, an attacker could use this ASLR bypass vulnerability in conjunction with another vulnerability, such as a remote code execution vulnerability that could take advantage of the ASLR bypass to run arbitrary code.

How could an attacker exploit the vulnerability?
An attacker could tie this security feature bypass vulnerability to an additional vulnerability, usually a remote code execution vulnerability. The additional vulnerability would take advantage of the security feature bypass for exploitation. For example, a remote code execution vulnerability that is blocked by ASLR, could be exploited after a successful ASLR bypass.

What systems are primarily at risk from the vulnerability?
Both workstations and servers are at risk from this vulnerability.

What does the update do?
The update addresses the vulnerability by correcting how RPC handles the freeing of malformed 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.

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

Windows 7 (all editions)

Reference Table

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