Microsoft Security Bulletin MS08-032 - Moderate Cumulative Security Update of ActiveX Kill Bits (950760)

Microsoft Security Bulletin MS08-032 - Moderate
Cumulative Security Update of ActiveX Kill Bits (950760)
Published: June 10, 2008

Version: 1.0
General Information
Executive Summary

This security update resolves a publicly reported vulnerability for the Microsoft Speech API. The vulnerability could allow remote code execution if a user viewed a specially crafted Web page using Internet Explorer and has the Speech Recognition feature in Windows enabled. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. This update also includes a kill bit for software produced by BackWeb.

The security update is rated Moderate for Microsoft Windows 2000 Service Pack 4; all supported editions of Windows XP; and all editions of the original release version of Windows Vista. However, the kill bit deployment also includes Windows Vista Service Pack 1.

For all other supported versions of Windows, this security update is rated Low. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by setting a kill bit so the vulnerable controls do not run in Internet Explorer. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection under the next section, Vulnerability Information.

Recommendation. Microsoft recommends that customers consider applying the security update.

Known Issues. No known issues.
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Affected and Non-Affected Software

The software listed here 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.

Affected Software
Operating System Maximum Security Impact Aggregated Severity Rating Bulletins Replaced by This Update

Microsoft Windows 2000 Service Pack 4

Remote Code Execution

Moderate

MS08-023

Windows XP Service Pack 2

Remote Code Execution

Moderate

MS08-023

Windows XP Service Pack 3

Remote Code Execution

Moderate

None

Windows XP Professional x64 Edition and Windows XP Professional x64 Edition Service Pack 2

Remote Code Execution

Moderate

MS08-023

Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2

Remote Code Execution

Low

MS08-023

Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Remote Code Execution

Low

MS08-023

Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems

Remote Code Execution

Low

MS08-023

Windows Vista and Windows Vista Service Pack 1

Remote Code Execution

Moderate

MS08-023

Windows Vista x64 Edition and Windows Vista x64 Edition Service Pack 1

Remote Code Execution

Moderate

MS08-023

Windows Server 2008 for 32-bit Systems*

Remote Code Execution

Low

MS08-023

Windows Server 2008 for x64-based Systems*

Remote Code Execution

Low

MS08-023

Windows Server 2008 for Itanium-based Systems

Remote Code Execution

Low

MS08-023

*For supported editions of Windows Server 2008, the same severity rating applies whether or not installed using the Server Core installation option. For more information on this installation option, see Server Core. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008; see Compare Server Core Installation Options.

Note for Affected Software Microsoft does not rate the severity of third party controls for which this update sets a kill bit. However, the kill bit will be deployed across all platforms, including a platform which is not affected by a vulnerability in Microsoft software. See also the subsection, “Third Party Kill Bits,” in this section.
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Frequently Asked Questions (FAQ) Related to This Security Update

What is a kill bit?
A security feature in Microsoft Internet Explorer makes it possible to prevent an ActiveX control from ever being loaded by the Internet Explorer HTML-rendering engine. This is done by making a registry setting and is referred to as setting the kill bit. After the kill bit is set, the control can never be loaded, even when it is fully installed. Setting the kill bit makes sure that even if a vulnerable component is introduced or is re-introduced to a system, it remains inert and harmless.

For more information on a kill bit, see Microsoft Knowledge Base Article 240797: How to stop an ActiveX control from running in Internet Explorer.

What is a security update of ActiveX kill bits?
This security update only contains the class IDs (CLSID) of certain ActiveX controls that are the basis of this security update. This security bulletin lists these CLSIDs in the Vulnerability Section.

Why does this update not contain any binary files?
This update only makes changes to the registry to disable the control from instantiating in Internet Explorer.

Should I install this update if I do not have the affected component installed or use the affected platform?
Yes. Installing this update will block the vulnerable control from running in Internet Explorer.

Do I need to reapply this update if I install an ActiveX control discussed in this security update at a later date?
No, reapplying this update is not required. The kill bit will block Internet Explorer from running the control even if the control is installed at a later date.

Does this update contain any kill bits that are not Microsoft-specific?
Yes. Microsoft has been requested by an organization to set the kill bit for a control that the organization owns and has found to be vulnerable.

Does this update contain kill bits that were previously shipped in an Internet Explorer security update?
No, this update does not include kill bits that were previously shipped in an Internet Explorer security update. We recommend that you install the latest Cumulative Security Update for Internet Explorer.

Why does this security update have different severity levels for different Windows operating systems?
This update has different severity levels because different mitigations apply to the vulnerability depending on the operating system. One such mitigation is that Internet Explorer on Windows Server 2003 and Windows Server 2008 runs in a restricted mode known as Enhanced Security Configuration.

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 have been tested to determine which releases are affected. Other releases are past their support life cycle. To determine the support life cycle for your software release, visit Microsoft Support Lifecycle.

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. For more information about the Windows Product Lifecycle, visit the following Microsoft Support Lifecycle. For more information about the extended security update support period for these software releases, visit the Microsoft Product Support Services Web site.

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, visit the Microsoft Worldwide Information Web site, select the country, 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 Windows Operating System Product Support Lifecycle FAQ.
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Vulnerability Information

Severity Ratings and Vulnerability Identifiers
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software Speech API Vulnerability - CVE-2007-0675 Aggregate Severity Rating

Microsoft Windows 2000 Service Pack 4

Moderate
Remote Code Execution

Moderate

Windows XP Service Pack 2 and Windows XP Service Pack 3

Moderate
Remote Code Execution

Moderate

Windows XP Professional x64 Edition and Windows XP Professional x64 Edition Service Pack 2

Moderate
Remote Code Execution

Moderate

Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2

Low
Remote Code Execution

Low

Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Low
Remote Code Execution

Low

Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems

Low
Remote Code Execution

Low

Windows Vista

Moderate
Remote Code Execution

Moderate

Windows Vista Service Pack 1

Not affected

None

Windows Vista x64 Edition and Windows Vista x64 Edition Service Pack 1

Moderate
Remote Code Execution

Moderate

Windows Server 2008 for 32-bit Systems*

Low
Remote Code Execution

Low

Windows Server 2008 for x64-based Systems*

Low
Remote Code Execution

Low

Windows Server 2008 for Itanium-based Systems

Low
Remote Code Execution

Low

*For supported editions of Windows Server 2008, the same severity rating applies whether or not installed using the Server Core installation option. For more information on this installation option, see Server Core. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008; see Compare Server Core Installation Options.

Note for Affected Software Microsoft does not rate the severity of third party controls for which this update sets a kill bit. However, the kill bit will be deployed across all platforms, including a platform which is not affected by a vulnerability in Microsoft software. See also the subsection, “Third Party Kill Bits,” in this section.
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Speech API Vulnerability - CVE-2007-0675

A remote code execution vulnerability exists in the Speech Components sapi.dll. An attacker could exploit the vulnerability by constructing a specially crafted Web page. When a user views the Web page, the vulnerability could allow remote code execution. The user must have the Speech Recognition feature in Windows enabled. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged on user.

This control was never intended to be instantiated in Internet Explorer.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2007-0675.

Mitigating Factors for Speech API Vulnerability - CVE-2007-0675

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:
•

By default the speech recognition feature of Windows Vista is not enabled.
•

In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail or Instant Messenger message that takes users to the attacker's Web site.
•

An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
•

By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 runs in a restricted mode that is known as Enhanced Security Configuration. This mode sets the security level for the Internet zone to High. This is a mitigating factor for Web sites that you have not added to the Internet Explorer Trusted sites zone. See the FAQ subsection of this vulnerability section for more information about Internet Explorer Enhanced Security Configuration.
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Workarounds for Speech API Vulnerability - CVE-2007-0675

Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:
•

Prevent COM objects from running in Internet Explorer

You can disable attempts to instantiate a COM object in Internet Explorer by setting the kill bit for the control in the registry.

Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

For detailed steps that you can use to prevent a control from running in Internet Explorer, see Microsoft Knowledge Base Article 240797. Follow these steps in this article to create a Compatibility Flags value in the registry to prevent a COM object from being instantiated in Internet Explorer.

Note The Class Identifiers and corresponding files where the ActiveX objects are contained are documented under “What does the update do?” in the “FAQ for Speech API Vulnerability - CVE-2007-0675” section. Replace {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX} below with the Class Identifiers found in this section.

To set the kill bit for a CLSID with a value of {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}, paste the following text in a text editor such as Notepad. Then, save the file by using the .reg file name extension.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{ XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX }]
"Compatibility Flags"=dword:00000400

You can apply this .reg file to individual systems by double-clicking it. You can also apply it across domains by using Group Policy. For more information about Group Policy, visit the following Microsoft Web sites:
•

Group Policy collection
•

What is Group Policy Object Editor?
•

Core Group Policy tools and settings

Note You must restart Internet Explorer for your changes to take effect.
•

Impact of Workaround: There is no impact as long as the object is not intended to be used in Internet Explorer.
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FAQ for Speech API Vulnerability - CVE-2007-0675

What is the scope of the vulnerability?
This is a remote code execution vulnerability. The user must have the Speech Recognition feature in Windows enabled. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on user.

If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

What causes the vulnerability?
When the speech recognition feature is activated and configured, it may be possible via playing an audio file in Internet Explorer, to issue commands in such a way that an attacker could execute arbitrary code.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

It is not possible through the use of voice commands to get the system to perform privileged functions such as creating a user without being prompted by UAC for Administrator credentials. The UAC prompt cannot be manipulated by voice commands by default. There are additional barriers that would make an attack difficult including speaker and microphone placement, microphone feedback, and the clarity of the dictation.

How could an attacker exploit the vulnerability?
An attacker could host a specially crafted Web site that is designed to exploit this vulnerability through Internet Explorer and then convince a user to view the Web site. This can also include compromised Web sites and Web sites that accept or host user-provided content or advertisements. These Web sites could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or in an Instant Messenger request that takes users to the attacker's Web site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.

I am running Internet Explorer for Windows Server 2003 or Windows Server 2008. Does this mitigate this vulnerability?
Yes. By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 runs in a restricted mode that is known as Enhanced Security Configuration. Enhanced Security Configuration is a group of preconfigured settings in Internet Explorer that can reduce the likelihood of a user or administrator downloading and running specially crafted Web content on a server. This is a mitigating factor for Web sites that you have not added to the Internet Explorer Trusted sites zone. See also Managing Internet Explorer Enhanced Security Configuration.

What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user be logged on and visit a Web site for any malicious action to occur. Therefore, any systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability. Systems that have activated the speech recognition feature are at risk from this vulnerability.

What does the update do?
This update sets the kill bit for a list of Class Identifiers (CLSIDs).

The Class Identifiers and corresponding files are as follows:
Class Identifier File

{47206204-5eca-11d2-960f-00c04f8ee628}

sapi.dll

{3bee4890-4fe9-4a37-8c1e-5e7e12791c1f}

sapi.dll

Why does this security update not include Windows Vista Service Pack 1?
This update does not set kill bits for Windows Vista Service Pack 1 because the vulnerability described by CVE-2007-0675 has been addressed in the service pack update.

What is SAPI?
SAPI is the Microsoft Speech Application Programming interface that is available for developers to add speech recognition and text-to-speech capabilities to applications.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
Yes. This vulnerability has been publicly disclosed. It has been assigned Common Vulnerability and Exposure number CVE-2007-0675. It also has been named “Vista Speach Recognition” by the larger security community.

When this security bulletin 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 bulletin was originally issued.
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Third-Party Kill Bits

This update includes kill bits that will prevent the following ActiveX controls from being run in Internet Explorer:
•

BackWeb has released a security bulletin and an update that addresses a vulnerability. Please see the security bulletin from BackWeb for more information and download locations. This kill bit is being set at the request of the owner of the ActiveX control. Customers who require support for this control should contact BackWeb. The class identifiers (CLSIDs) for this ActiveX control are:
•

{40F23EB7-B397-4285-8F3C-AACE4FA40309}

Other Information
Support
•

Customers in the U.S. and Canada can receive technical support from Microsoft Product Support Services at 1-866-PCSAFETY. There is no charge for support calls that are associated with security updates.
•

International customers can receive support from their local Microsoft subsidiaries. There is no charge for support that is associated with security updates. For more information about how to contact Microsoft for support issues, visit the International Support Web site.

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 (June 10, 2008): Bulletin published.