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Vulnerability in Microsoft Malware Protection Engine Could Allow Elevation of Privilege

Vulnerability in Microsoft Malware Protection Engine Could Allow Elevation of Privilege

Published: February 23, 2011 | Updated: March 08, 2011

Version: 1.1

General Information

Executive Summary

Microsoft is releasing this security advisory to help ensure customers are aware that an update to the Microsoft Malware Protection Engine also addresses a security vulnerability reported to Microsoft. The update addresses a privately reported vulnerability that could allow elevation of privilege if the Microsoft Malware Protection Engine scans a system after an attacker with valid logon credentials has created a specially crafted registry key. An attacker who successfully exploited the vulnerability could gain the same user rights as the LocalSystem account. The vulnerability could not be exploited by anonymous users.

Since the Microsoft Malware Protection Engine is a part of several Microsoft anti-malware products, the update to the Microsoft Malware Protection Engine is installed along with the updated malware definitions for the affected products. Administrators of enterprise installations should follow their established internal processes to ensure that the definition and engine updates are approved in their update management software, and that clients consume the updates accordingly.

Typically, no action is required of enterprise administrators or end users to install this update, because the built-in mechanism for the automatic detection and deployment of this update will apply the update within the next 48 hours. The exact time frame depends on the software used, Internet connection, and infrastructure configuration.

Advisory Details

Issue References

For more information about this issue, see the following references:

ReferencesIdentification
CVE ReferenceCVE-2011-0037
Last version of the Microsoft Malware Protection Engine affected by this vulnerabilityVersion 1.1.6502.0*
First version of the Microsoft Malware Protection Engine with this vulnerability addressedVersion 1.1.6603.0**

*This version is the last version of the Microsoft Malware Protection Engine that is affected by the vulnerability.

**If your version of the Microsoft Malware Protection Engine is equal to or greater than this version, then you are not affected by this vulnerability and do not need to take any further action. For more information on how to verify the engine version number that your software is currently using, see the section, "Verifying Update Installation", in Microsoft Knowledge Base Article 2510781.

Affected Software and Severity Ratings

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, visit Microsoft Support Lifecycle.

The Microsoft Malware Protection Engine is a part of several Microsoft anti-malware products. Depending upon which affected Microsoft anti-malware product is installed, this update may have different severity ratings. The following severity ratings assume the potential maximum impact of the vulnerability.

Affected Software

Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Anti-malware SoftwareMicrosoft Malware Protection Engine Vulnerability - CVE-2011-0037
Windows Live OneCareImportant 
Elevation of Privilege
Microsoft Security EssentialsImportant 
Elevation of Privilege
Microsoft Windows DefenderImportant 
Elevation of Privilege
Microsoft Forefront Client SecurityImportant 
Elevation of Privilege
Microsoft Forefront Endpoint Protection 2010Important 
Elevation of Privilege
Microsoft Malicious Software Removal Tool[1]Important 
Elevation of Privilege

[1]Applies only to February 2011 or earlier versions of the Microsoft Malicious Software Removal Tool.

Non-Affected Software

Anti-malware Software
Microsoft Antigen for Exchange
Microsoft Antigen for SMTP Gateway
Forefront Security for Exchange Server
Forefront Protection 2010 for Exchange Server
Forefront Threat Management Gateway 2010
Microsoft Forefront Security for SharePoint
Forefront Security for Office Communications Server
Microsoft Standalone System Sweeper (part of Microsoft Diagnostics and Recovery Toolset)

The following table provides an exploitability assessment of the vulnerability addressed in this advisory.

How do I use this table?

Use this table to learn about the likelihood of functioning exploit code being released within 30 days of this advisory release. You should review the assessment below, in accordance with your specific configuration, in order to prioritize your deployment. For more information about what these ratings mean, and how they are determined, please see Microsoft Exploitability Index.

Vulnerability TitleCVE IDExploitability Index AssessmentKey Notes
Microsoft Malware Protection Engine VulnerabilityCVE-2011-00371 - Consistent exploit code likelyThis is an elevation of privilege vulnerability

Why was this advisory revised on March 8, 2011? 
When this advisory was first released, an updated version of the Malicious Software Removal Tool (MSRT) was not available. Microsoft released an updated version of the MSRT on Tuesday, March 8, 2011 that addresses the vulnerability. Versions of the MSRT released on or after that date are not affected by the vulnerability described in this security advisory.

Why was no update for the Malicious Software Removal Tool (MSRT) available when this Security Advisory was first released? 
The vulnerability could only be exploited through February 2011 or earlier versions of the MSRT when the MSRT was initially offered and downloaded using Automatic Updates. Microsoft released an updated version to address the issue in the Malicious Software Removal Tool on Tuesday, March 8, 2011. Versions of the MSRT released on or after that date are not vulnerable to the issue described in this security advisory.

MSRT runs only once when downloaded using Automatic Updates. An attacker could not exploit this vulnerability by running a vulnerable version of the MSRT manually.

Is Microsoft releasing a Security Bulletin to address this vulnerability? 
No. Microsoft is releasing this informational security advisory to help ensure customers are aware that this Microsoft Malware Protection Engine update also addresses a security vulnerability reported to Microsoft.

Typically, no action is required of enterprise administrators or end users to install this update.

Why is typically no action required to install this update? 
In response to a constantly changing threat landscape, Microsoft frequently updates malware definitions and the Microsoft Malware Protection Engine. In order to be effective in helping protect against new and prevalent threats, anti-malware software must be kept up to date with these updates in a timely manner.

For enterprise deployments as well as end users, the default configuration in Microsoft anti-malware software helps ensure that malware definitions and the Microsoft Malware Protection Engine are kept up to date automatically. Product documentation also recommends that products are configured for automatic updating.

Best practices recommend that customers regularly verify whether software distribution, such as the automatic deployment of Microsoft Malware Protection Engine updates and malware definitions, is working as expected in their environment.

How often are the Microsoft Malware Protection Engine and malware definitions updated? 
Microsoft typically releases an update for the Microsoft Malware Protection Engine once a month or as needed to protect against new threats. Microsoft also typically updates the malware definitions three times daily and can increase the frequency when needed.

Depending on which Microsoft anti-malware software is used and how it is configured, the software may search for engine and definition updates every day when connected to the Internet, up to multiple times daily. Customers can also choose to manually check for updates at any time.

How can I install the update? 
Administrators of enterprise installations should follow their established internal processes to ensure that the definition and engine updates are approved in their update management software, and that clients consume the updates accordingly.

For more information on installing the latest definitions, visit the Microsoft Malware Protection Center, or refer to your product documentation.

For end users, no further action is required because this security update will be downloaded and installed automatically through automatic updating or through their anti-malware software. For information on how to configure anti-malware software, refer to your product documentation.

For end users who want to install this update manually, refer to the following table.

Note Updates available through Microsoft Update will be listed as Important. Look for the appropriate update for your software with a name similar to the example listed in parenthesis () in the table below.

SoftwareUpdate MechanismOther methods of updating
Microsoft Security EssentialsMicrosoft UpdateHow to manually download the latest definition updates for Microsoft Security Essentials
Microsoft Windows DefenderWindows UpdateInstall the latest Windows Defender definition updates
Microsoft Forefront Client SecurityMicrosoft UpdateInstall the latest Microsoft Forefront Security definition updates
Microsoft Forefront Endpoint Protection 2010Microsoft Update
(Example: "Definition Update for Microsoft Forefront Endpoint Protection 2010")
Install the latest Microsoft Forefront Security definition updates
Microsoft Malicious Software Removal ToolWindows UpdateMalicious Software Removal Tool

Note For additional information about deployment of this update for specific Microsoft anti-malware products, refer to Microsoft Knowledge Base Article 2510781.

What is the Microsoft Malware Protection Engine? 
The Microsoft Malware Protection Engine, mpengine.dll, provides the scanning, detection, and cleaning capabilities for Microsoft antivirus and antispyware software. For more information, see the section, Microsoft Malware Protection Engine Deployment, later in this advisory.

Where can I find more information about Microsoft anti-malware technology? 
For more information, visit the Microsoft Malware Protection Center Web site.

Why is ISA Server not listed in the affected or non-affected software list? 
While Microsoft Internet Security and Acceleration (ISA) Server is the predecessor of Forefront Threat Management Gateway 2010 (TMG), ISA Server does not contain the Microsoft Malware Protection Engine and as such is not considered in this advisory. Malware Scanning using the Microsoft Malware Protection Engine was first introduced in Forefront TMG. For more information about new features in Forefront TMG, see the Forefront Threat Management Gateway 2010 page, What's New.

What is the scope of the vulnerability? 
This is an elevation of privilege vulnerability. An attacker who successfully exploited this vulnerability could execute arbitrary code in the security context of the LocalSystem account. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

What causes the vulnerability? 
The vulnerability is caused when the Microsoft Malware Protection Engine fails to properly process a registry key that an attacker has set to a specially crafted value.

What might an attacker use the vulnerability to do? 
An attacker who successfully exploited this vulnerability could execute arbitrary code in the security context of the LocalSystem account and take complete control of the system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

What is the LocalSystem account? 
The LocalSystem account is a predefined local account used by the service control manager. It has extensive privileges on the local computer, and acts as the computer on the network. Its token includes the NT AUTHORITY\SYSTEM and BUILTIN\Administrators SIDs; these accounts have access to most system objects. A service that runs in the context of the LocalSystem account inherits the security context of the Service Control Manager. Most services do not need such a high privilege level. For more information, see the MSDN article, LocalSystem Account.

How could an attacker exploit the vulnerability? 
This vulnerability requires that a specially crafted registry location be scanned by an affected version of the Microsoft Malware Protection Engine. To exploit this vulnerability, an attacker would first have to log on to the system, and then set a user registry key to a specially crafted value.

If the affected anti-malware software has real-time protection turned on, the Microsoft Malware Protection Engine will scan the location automatically, leading to exploitation of the vulnerability and allowing the attacker to take complete control of the affected system. If real-time scanning is not enabled, the attacker would need to wait until a scheduled scan occurs in order for the vulnerability to be exploited and to take complete control of the affected system. An attacker could not exploit the vulnerability by initiating a scan manually.

In addition, exploitation of the vulnerability could occur when the system is scanned using an affected version of the Malicious Software Removal Tool (MSRT). However, if the current version of the MSRT has already run on the system, an attacker could not use the MSRT to exploit this vulnerability.

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 correcting the manner in which the Microsoft Malware Protection Engine processes values read from the registry.

When this security advisory was issued, had this vulnerability been publicly disclosed? 
No. Microsoft received information about this vulnerability through coordinated vulnerability disclosure.

When this security advisory 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 advisory was originally issued.

Mitigating Factors

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of this issue. The following mitigating factors may be helpful in your situation:

  • An attacker must have valid logon credentials to exploit this vulnerability. The vulnerability could not be exploited by anonymous users.
  • An attacker could have used the February 2011 or earlier versions of the Malicious Software Removal Tool (MSRT) to exploit this vulnerability, only if that version of the MSRT had not already run on the system. When this advisory was first released, for the majority of end users, the February 2011 version of the MSRT would already have been downloaded and run automatically through automatic updating. Microsoft released an updated version to address the issue in the Malicious Software Removal Tool on Tuesday, March 8, 2011. Versions of the MSRT released on or after that date are not vulnerable to the issue described in this security advisory.

Suggested Actions

There is typically no action required for enterprise administrators or end users to install this update. Microsoft recommends that customers keep malware definitions up to date at all times. Customers should verify that the latest version of the Microsoft Malware Protection Engine and definition updates are being actively downloaded and installed for their Microsoft anti-malware products.

Administrators of enterprise anti-malware deployments should ensure that their update management software is configured to automatically approve and distribute engine updates and new malware definitions. Enterprise administrators should also verify that the latest version of the Microsoft Malware Protection Engine and definition updates are being actively downloaded, approved and deployed in their environment.

For end-users, the affected software provide built-in mechanisms for the automatic detection and deployment of this update. For these customers the update will be applied within 48 hours of its availability. The exact time frame depends on the software used, Internet connection, and infrastructure configuration. End users that do not wish to wait can manually update their anti-malware software.

For more information on how to manually update the Microsoft Malware Protection Engine and malware definitions, refer to Microsoft Knowledge Base Article 2510781, or refer to the section, Frequently Asked Questions (FAQ) About this Advisory.

Other Information

Acknowledgments

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

  • Cesar Cerrudo of Argeniss for reporting the Microsoft Malware Protection Engine Vulnerability (CVE-2011-0037)

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 visit the active protections Web sites provided by program partners, listed in Microsoft Active Protections Program (MAPP) Partners.

Feedback

Support

  • Customers in the United States and Canada can receive technical support from Security Support. For more information about available support options, see Microsoft Help and Support.
  • International customers can receive support from their local Microsoft subsidiaries. For more information about how to contact Microsoft for international support issues, visit International Support.
  • Microsoft TechNet Security provides additional information about security in Microsoft products.

Disclaimer

The information provided in this advisory 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 (February 23, 2011): Advisory published.
  • V1.1 (March 8, 2011): Revised advisory FAQ to announce updated version of the MSRT and added Forefront Security for Exchange Server to the list of non-affected software.

Built at 2014-04-16T02:39:51Z-07:00

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