Windows Updates for Media Center, .NET, and LRPC

Severity: Medium

Summary:

  • These vulnerabilities affect: All current versions of Windows (and related components like .NET Framework)
  • How an attacker exploits them: Multiple vectors of attack, such as enticing you into opening maliciously crafted Office file.
  • Impact: In the worst case, an remote attacker can gain complete control of your Windows computer
  • What to do: Install the appropriate Microsoft patches as soon as possible, or let Windows Automatic Update do it for you

Exposure:

Today, Microsoft released five security bulletins describing seven vulnerabilities in Windows and related components, such as the .NET Framework. A remote attacker could exploit the worst of these flaws to potentially gain complete control of your Windows PC. We recommend you download, test, and deploy these critical updates as quickly as possible.

The summary below lists the vulnerabilities, in order from highest to lowest severity.

  • MS14-043:  Windows Media Center Code Execution Flaw

Windows Media Center is the media player and Digital Video Recording (DVR) application that ships with the popular operating system. MCplayer.dll, a component Media Center uses for audio and video playback, suffers from a “use after free” vulnerability. By tricking you into running a specially crafted Office file, a remote attacker could leverage this flaw to execute code on your computer, with your privileges. If you’re a local adminstrator, the attacker could gain complete control of your machine. Note, this flaw mostly affects the latest versions of Windows.

Microsoft rating: Critical

  • MS14-045:  Multiple Kernel-Mode Driver Elevation of Privilege Vulnerabilities

The kernel is the core component of any computer operating system. Windows also ships with a kernel-mode device driver (win32k.sys), which handles the OS’s device interactions at a kernel level. The Windows kernel-mode driver suffers from three local code execution flaws. The flaws differ technically, but most have to do with the kernel-mode driver improperly handling certain objects, which can result in memory corruptions. Smart attackers can leverage memory corruption flaws to execute code. In a nutshell, if a local attacker can run a specially crafted application, he could leverage most of these flaws to gain complete control of your Windows computers. However, in order to run his malicious program, the attacker first needs to gain local access to your Windows computer, or needs to trick you into running the program yourself, which somewhat lessens the severity of this vulnerability.

Microsoft rating: Important

  • MS14-046:  .NET Framework ASLR Bypass Flaw

The .NET Framework is software framework used by developers to create new Windows and web applications. Address Space Layout Randomization (ASLR) is a memory obfuscation technique that some operating systems use to make it harder for attackers to find specific things in memory, which in turn makes it harder for them to exploit memory corruption flaws. In short, the .NET framework doesn’t use ASLR protection. This means attackers can leverage .NET to bypass Windows’ ASLR protection features. This flaw alone doesn’t allow an attacker to gain access to your Windows computer. Rather, it can help make other memory corruption vulnerabilities easier to exploit. This update fixes the ASLR bypass hole.

Microsoft rating: Important

Local Remote Procedure Call (LRPC) is a protocol Microsoft Windows uses to allow processes to communicate with each other and execute tasks, whether on the same computer or another computer over the network. It suffers from a ASLR bypass vulnerability that has the same scope and impact as the .NET one described above.

Microsoft rating: Important

  • MS14-049:  Windows Installer Service Elevation of Privilege Flaw

As its name suggests, the Windows Installer services is a component that helps you install and configure stuff in Windows. It suffers from a privilege escalation vulnerability involving the way it improperly handles the repair of a previous application. If a local attacker can log into one of your Windows systems and run a specially crafted application, he could exploit this flaw to gain complete control of the system (even if he started out with only Guest privileges). Of course, the attacker would need valid login credentials, which significantly lowers the severity of this issue.

Microsoft rating: Important

Solution Path:

Microsoft has released various updates that correct all of these vulnerabilities. You should download, test, and deploy the appropriate updates throughout your network immediately. If you choose, you can also let Windows Update automatically download and install them for you. As always, you should test your updates before deploying them.

The links below point directly to the “Affected and Non-Affected Software” section of each bulletin, where you can find links to the various updates:

For All WatchGuard Users:

Though WatchGuard’s XTM appliances offer defenses that can mitigate the risk of some of these flaws (such as blocking Office files), attackers can exploit others locally. Since your gateway XTM appliance can’t protect you against local attacks, we recommend you install Microsoft’s updates to completely protect yourself from these flaws.

Status:

Microsoft has released patches correcting these issues.

References:

This alert was researched and written by Corey Nachreiner, CISSP (@SecAdept).


What did you think of this alert? Let us know at your.opinion.matters@watchguard.com.

About Corey Nachreiner

Corey Nachreiner has been with WatchGuard since 1999 and has since written more than a thousand concise security alerts and easily-understood educational articles for WatchGuard users. His security training videos have generated hundreds of letters of praise from thankful customers and accumulated more than 100,000 views on YouTube and Google Video. A Certified Information Systems Security Professional (CISSP), Corey speaks internationally and is often quoted by other online sources, including C|NET, eWeek, and Slashdot. Corey enjoys "modding" any technical gizmo he can get his hands on, and considers himself a hacker in the old sense of the word.

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