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 |
| 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. |
| 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. |