Four Windows Bulletins Fix Group Policy, .NET, and iSCSI Flaws

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, though most require authenticated attackers to do things locally
  • Impact: In the worst case, an authenticated 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 four security bulletins describing five vulnerabilities in Windows and related components, such as the .NET Framework. An authenticated 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.

  • MS14-025: Group Policy Preferences Password Elevation of Privilege Flaw

Group Policy is the Windows feature that allows administrators to push configuration and settings to other Windows computers throughout their network. Group Policy Preferences are simply an extension of settings you can push via Group Policy. Microsoft’s alert describes a vulnerability in the way Active Directory sends password information with certain Group Policy Preferences. If you use Group Policy to set system administrator accounts, map drives, or run scheduled tasks—all things that require privileges—Group Policy stores an encrypted version of the password or credential needed for this task on the local computer. Local, authenticated attackers can then use that information to crack the password, and perhaps elevate their privileges. For instance, if you use your domain administrator account to run a particular scheduled task on every Windows computer network when it boots, local Windows users may have the information they need to crack your domain administrator account. That said, attackers would need valid credentials to log into one of your windows computers in order to exploit this flaw. So this primarily poses an insider risk.

Microsoft rating: Important

  • MS14-026:  .NET Framework Elevation of Privilege Vulnerability

The .NET Framework is a software framework used by developers to create custom Windows and web applications. Though it only ships by default with Windows Vista, you’ll find it on many Windows computers.

The .NET Framework suffers from an unspecified elevation of privilege vulnerability. If an authenticated attacker can send specially crafted data to an app that uses .NET Remoting, he can exploit this flaw to execute code on that system with full system privileges.

Microsoft rating: Important

  • MS14-027:  Windows Shell Elevation of Privilege Vulnerability

The Windows Shell is the primary GUI component for Windows. It suffers from a vulnerability having to do with its ShellExecute Application Programming Interface (API). If a local attacker can log in to one of your Windows systems and run a specially crafted program, he can exploit this flaw to execute code with local administrator privileges, thus gaining full control of the computer.

Microsoft rating: Important

  • MS14-028:  Two iSCSI DoS Vulnerabilities

iSCSI is a standard that supports network based storage devices. The Windows iSCSI component suffers from two Denial of Service (DoS) vulnerabilities. By sending a large amount of specially crafted packets to the iSCSI service (TCP 3260), an attacker could exploit this flaw to cause the iSCSI service to stop responding. Of course, the attacker needs access to the iSCSI service, which most administrator might block with their firewall.

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. I especially recommend you test the Group Policy Preference update before deploy it, as it may slightly change the way Group Policy Preferences work.

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 TCP port 3260), 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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