Security Bulletin

Microsoft Security Bulletin MS13-058 - Important

Vulnerability in Windows Defender Could Allow Elevation of Privilege (2847927)

Published: July 09, 2013

Version: 1.0

General Information

Executive Summary

This security update resolves a privately reported vulnerability in Windows Defender for Windows 7 and Windows Defender when installed on Windows Server 2008 R2. The vulnerability could allow elevation of privilege due to the pathnames used by Windows Defender. An attacker who successfully exploited this vulnerability could execute arbitrary code and take complete control of an affected system. The attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. An attacker must have valid logon credentials to exploit this vulnerability. The vulnerability could not be exploited by anonymous users.

This security update is rated Important for Windows Defender for Windows 7 and Windows Server 2008 R2. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by correcting pathnames used by Windows Defender. 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

Knowledge Base Article 2847927
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

Operating System Component Maximum Security Impact Aggregate Severity Rating Updates Replaced
Windows 7 for 32-bit Systems Service Pack 1 Windows Defender for Windows 7 (x86) 
(2847927)
Elevation of Privilege Important None
Windows 7 for x64-based Systems Service Pack 1 Windows Defender for Windows 7 (x64) 
(2847927)
Elevation of Privilege Important None
Windows Server 2008 R2 for x64-based Systems Service Pack 1 Windows Defender when installed on Windows Server 2008 R2 (x64) 
(2847927)
Elevation of Privilege Important None
  **Non-Affected Software** | Antimalware Software | |-------------------------------------------------------------------------| | Windows Defender for Windows XP and Windows Server 2003 | | Windows Defender for Windows Vista and Windows Server 2008 | | Windows Defender for Windows 8 | | Windows Defender for Windows RT | | Windows Defender Offline   | | Microsoft Forefront Server Security Management Console | | Microsoft Internet Security and Acceleration (ISA) Server | | Microsoft Antigen for Exchange | | Microsoft Antigen for SMTP Gateway | | Microsoft System Center 2012 Endpoint Protection for Linux | | Microsoft System Center 2012 Endpoint Protection for Mac | | Microsoft Forefront Protection 2010 for Exchange Server | | Microsoft Forefront Security for Exchange Server Service Pack 2 | | Microsoft Forefront Security for Office Communications Server | | Microsoft Forefront Threat Management Gateway 2010 | | Microsoft Forefront Client Security | | Microsoft Forefront Endpoint Protection 2010 | | Microsoft Forefront Security for SharePoint Service Pack 3 | | Microsoft Malicious Software Removal Tool | | Microsoft Security Essentials | | Microsoft Security Essentials Prerelease | | Microsoft System Center 2012 Endpoint Protection | | Microsoft System Center 2012 Endpoint Protection Service Pack 1 | | Microsoft System Center 2012 Endpoint Protection for Mac Service Pack 1 | | Windows Intune Endpoint Protection |   Update FAQ ---------- **What is Windows Defender?**  In Windows 7, Windows Defender is a free antispyware software. It helps protect a user’s computer against malware. Windows Defender is installed by default in Windows 7. **Where can I find more information about Microsoft antimalware technology?**  For more information, visit the [Microsoft Malware Protection Center](http://www.microsoft.com/security/portal/) website. **I am running Windows 7 but I have Windows Defender disabled. Do need to install this update?**  No. If Windows Defender is disabled, you do not need to install this update. However, because Windows Defender is included as a component of Windows 7, Microsoft recommends that customers apply the update at the earliest opportunity. **How can** **Windows Defender** **be** **installed on systems running Windows Server 2008 R2?**  Windows Defender is included with the Desktop Experience feature for Windows Server 2008 R2. For more information, see [Desktop Experience Overview](http://technet.microsoft.com/library/cc772567). **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](http://go.microsoft.com/fwlink/?linkid=21742) 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](http://go.microsoft.com/fwlink/?linkid=169555). For more information about service packs for these software releases, see [Service Pack Lifecycle Support Policy](http://go.microsoft.com/fwlink/?linkid=89213). 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](http://go.microsoft.com/fwlink/?linkid=33329) 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](http://go.microsoft.com/fwlink/?linkid=169557). ### **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 [July bulletin summary](http://technet.microsoft.com/security/bulletin/ms13-jul). For more information, see [Microsoft Exploitability Index](http://technet.microsoft.com/security/cc998259).

Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Software Microsoft Windows 7 Defender Improper Pathname Vulnerability - CVE-2013-3154 Aggregate Severity Rating
Windows Defender for Windows 7 (x86) **Important**  Elevation of Privilege **Important**
Windows Defender for Windows 7 (x64) **Important**  Elevation of Privilege **Important**
Windows Defender when installed on Windows Server 2008 R2 (x64) **Important**  Elevation of Privilege **Important**
 

Microsoft Windows 7 Defender Improper Pathname Vulnerability - CVE-2013-3154

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 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. An attacker must have valid logon credentials to exploit this vulnerability. The vulnerability could not be exploited by anonymous users.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2013-3154.

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 to exploit this vulnerability. The vulnerability could not be exploited by anonymous users.
  • In a Windows 7 default configuration, a user running as a standard user account does not have permissions to write files to the root directory on the system. This mitigates the vulnerability because, in a default configuration, a standard user account would not have the necessary permissions to exploit the 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 by the improper use of pathnames when attempting to load an affected version of the Windows Defender service.

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.

An attacker must have valid logon credentials to exploit this vulnerability. The vulnerability could not be exploited by anonymous users.

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?
To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then place a specially crafted application in a location that could be used to exploit the vulnerability.

What systems are primarily at risk from the vulnerability?
Windows 7 workstations are primarily at risk from this vulnerability.

What does the update do?
The update addresses the vulnerability by correcting pathnames used by Windows Defender for Windows 7.

When this security advisory was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible 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 and had not seen any examples of proof of concept code published when this security advisory 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 (SCCM) 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 Defender for Windows 7

Reference Table

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

Security update file name For Windows Defender for supported editions of Windows 7 (x86):
Windows6.1-KB2847927-x86.msu
For Windows Defender for supported editions of Windows 7 (x64):
Windows6.1-KB2847927-x64.msu
Installation switches See Microsoft Knowledge Base Article 934307
Restart requirement This update does not require a restart. The installer stops the required services, applies the update, and then restarts the services. However, if the required services cannot be stopped for any reason, or if required files are being used, this update will require a restart. If this behavior occurs, a message appears that advises you to restart.
Removal information To uninstall an update installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, and then under Windows Update, click View installed updates and select from the list of updates.
File information See Microsoft Knowledge Base Article 2847927
Registry key verification Note A registry key does not exist to validate the presence of this update.
#### Windows Defender for Windows Server 2008 R2 **Reference Table** The following table contains the security update information for this software.

Security update file name For Windows Defender when installed on supported editions of Windows Server 2008 R2 (x64):
Windows6.1-KB2847927-x64.msu
Installation switches See Microsoft Knowledge Base Article 934307
Restart requirement This update does not require a restart. The installer stops the required services, applies the update, and then restarts the services. However, if the required services cannot be stopped for any reason, or if required files are being used, this update will require a restart. If this behavior occurs, a message appears that advises you to restart.
Removal information To uninstall an update installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, and then under Windows Update, click View installed updates and select from the list of updates.
File information See Microsoft Knowledge Base Article 2847927
Registry key verification Note A registry key does not exist to validate the presence of this update.
### Other Information #### Acknowledgments Microsoft [thanks](http://go.microsoft.com/fwlink/?linkid=21127) the following for working with us to help protect customers: - Alton Blom of [Reserve Bank of Australia](http://www.rba.gov.au/) for reporting the Microsoft Windows 7 Defender Improper Pathname Vulnerability (CVE-2013-3154) #### 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](http://go.microsoft.com/fwlink/?linkid=215201). #### Support **How to obtain help and support for this security update** - Help installing updates: [Support for Microsoft Update](http://support.microsoft.com/ph/6527) - Security solutions for IT professionals: [TechNet Security Troubleshooting and Support](http://technet.microsoft.com/security/bb980617.aspx) - Help protect your computer that is running Windows from viruses and malware: [Virus Solution and Security Center](http://support.microsoft.com/contactus/cu_sc_virsec_master) - Local support according to your country: [International Support](http://support.microsoft.com/common/international.aspx) #### 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 (July 9, 2013): Bulletin published. *Built at 2014-04-18T13:49:36Z-07:00*