Microsoft Security Bulletin MS08-023 - Critical

Microsoft Security Bulletin MS08-023 - Critical
Security Update of ActiveX Kill Bits (948881)
Published: April 8, 2008

Version: 1.0
General Information
Executive Summary

This security update resolves one privately reported vulnerability for a Microsoft product. This update also includes a kill bit for the Yahoo! Music Jukebox product. The vulnerability could allow remote code execution if a user viewed a specially crafted Web page using Internet Explorer. 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.

The security update is rated Critical for Internet Explorer 5.01 Service Pack 4 on Microsoft Windows 2000 Service Pack 4; Internet Explorer 6 Service Pack 1 when installed on Microsoft Windows 2000 Service Pack 4; Windows XP Service Pack 2; and Windows XP Professional x64 Edition and Windows XP Professional x64 Edition Service Pack 2.

The security update is rated Important for Windows Vista and Windows Vista Service Pack 1; and Windows Vista x64 Edition and Windows Vista x64 Edition Service Pack 1.

The security update is rated Moderate for all supported editions of Windows Server 2003.

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 apply the update immediately.

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 Component Maximum Security Impact Aggregated Severity Rating Bulletins Replaced by This Update

Microsoft Windows 2000 Service Pack 4

Microsoft Internet Explorer 5.01 Service Pack 4

Remote Code Execution

Critical

None

Microsoft Windows 2000 Service Pack 4

Microsoft Internet Explorer 6 Service Pack 1

Remote Code Execution

Critical

None

Windows XP Service Pack 2

Remote Code Execution

Critical

None

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

Remote Code Execution

Critical

None

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

Remote Code Execution

Moderate

None

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

Remote Code Execution

Moderate

None

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

Remote Code Execution

Moderate

None

Windows Vista and Windows Vista Service Pack 1

Remote Code Execution

Important

None

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

Remote Code Execution

Important

None

Windows Server 2008 for 32-bit Systems

Remote Code Execution

Low

None

Windows Server 2008 for x64-based Systems

Remote Code Execution

Low

None

Windows Server 2008 for Itanium-based Systems

Remote Code Execution

Low

None
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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?
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.

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 ActiveX Object Memory Corruption Vulnerability - CVE-2008-1086 Aggregate Severity Rating

Internet Explorer 5.01 Service Pack 4 on Microsoft Windows 2000 Service Pack 4

Critical
Remote Code Execution

Critical

Internet Explorer 6 Service Pack 1 when installed on Microsoft Windows 2000 Service Pack 4

Critical
Remote Code Execution

Critical

Windows XP Service Pack 2

Critical
Remote Code Execution

Critical

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

Critical
Remote Code Execution

Critical

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

Moderate
Remote Code Execution

Moderate

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

Moderate
Remote Code Execution

Moderate

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

Moderate
Remote Code Execution

Moderate

Windows Vista and Windows Vista Service Pack 1

Important
Remote Code Execution

Important

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

Important
Remote Code Execution

Important

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
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ActiveX Object Memory Corruption Vulnerability - CVE-2008-1086

A remote code execution vulnerability exists in the ActiveX control hxvz.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. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged on user

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-1086.

Mitigating Factors for ActiveX Object Memory Corruption Vulnerability - CVE-2008-1086

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:
•

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.
•

By default, this ActiveX control is not included in the default allow-list for ActiveX controls in Internet Explorer 7. Only customers who have explicitly approved this control by using the ActiveX opt-in feature are at risk to attempts to exploit this vulnerability. However, if a customer has used this ActiveX control in a previous version of Internet Explorer, then this ActiveX control is enabled to work in Internet Explorer 7, even if the customer has not explicitly approved it using the ActiveX opt-in feature.
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Workarounds for ActiveX Object Memory Corruption Vulnerability - CVE-2008-1086

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 ActiveX Object Memory Corruption Vulnerability - CVE-2008-1086” 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 ActiveX Object Memory Corruption Vulnerability - CVE-2008-1086

What is the scope of the vulnerability?
This is a remote code execution vulnerability. 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 ActiveX control is used in Internet Explorer, the control may corrupt the system state 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.

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. Does this mitigate this vulnerability?
Yes. By default, Internet Explorer on Windows Server 2003 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.

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

{314111b8-a502-11d2-bbca-00c04f8ec294}

hxvz.dll

{314111c6-a502-11d2-bbca-00c04f8ec294}

hxvz.dll

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

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.

Third Party Kill Bits

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

Yahoo! has released a security bulletin and an update that addresses the vulnerability in Yahoo! Music Jukebox. Please see the security bulletin from Yahoo! for more information and download locations. This kill bit is being set at the request of the owner of the ActiveX control. The class identifiers (CLSIDs) for this ActiveX control are:
•

{5f810afc-bb5f-4416-be63-e01dd117bd6c}
•

{22fd7c0a-850c-4a53-9821-0b0915c96139}

Other Information
Acknowledgments

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

An anonymous researcher working with the iDefense VCP for reporting the ActiveX Object Memory Corruption Vulnerability – CVE-2008-1086

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 (April 08, 2008): Bulletin published.