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Credit:
The information has been provided by Microsoft Security Bulletin MS07-008.
The original article can be found at:
http://www.microsoft.com/technet/security/bulletin/ms07-008.mspx
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Affected Software:
* Microsoft Windows 2000 Service Pack 4 - Download the update
* Microsoft Windows XP Service Pack 2 - Download the update
* Microsoft Windows XP Professional x64 Edition - Download the update
* Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1 - Download the update
* Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft Windows Server 2003 with SP1 for Itanium-based Systems - Download the update
* Microsoft Windows Server 2003 x64 Edition - Download the update
Non-Affected Software:
* Windows Vista
Mitigating Factors for HTML Help ActiveX Control Vulnerability - CVE-2007-0214:
* By default, all supported versions of Microsoft Outlook and Microsoft Outlook Express open HTML e-mail messages in the Restricted sites zone. The Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing Active Scripting and ActiveX controls from being used when reading HTML e-mail. However, if a user clicks on a link within an e-mail they could still be vulnerable to this issue through the Web-based attack scenario.
* By default, Internet Explorer on Windows Server 2003 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 have not been added to Internet Explorer Trusted sites zone.
Workarounds for HTML Help ActiveX Control Vulnerability - CVE-2007-0214:
Microsoft has tested the following workarounds. Although these workarounds will not correct the underlying vulnerability, they help block known attack vectors. When a workaround reduces functionality, it is identified in the following section.
* Temporarily prevent the HTML Help ActiveX control from running in Internet Explorer
To protect against this vulnerability, set the kill bit for the ActiveX control to
temporarily disable the HTML Help ActiveX and keep it from running in Internet Explorer.
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 the Registry Editor at your own risk.
The CLSID for an ActiveX control is a GUID for that control. You can prevent an ActiveX control from running in Internet Explorer by setting the kill bit so that the control is never called by Internet Explorer. The kill bit is a specific value for the Compatibility Flags DWORD value for the ActiveX control in the registry.
The CLSID for the HTML Help ActiveX control is {52a2aaae-085d-4187-97ea-8c30db990436}
For detailed steps about stopping an ActiveX control from running in Internet Explorer, see Microsoft Knowledge Base Article 240797. Follow these steps and create a Compatibility Flags value in the registry to prevent the HTML Help ActiveX control from being instantiated in Internet Explorer.
Note If you use this workaround you must reset this registry change by removing the same Compatibility Flags registry value. You should do this after you have applied this security update to regain normal functionality supplied by the HTML Help ActiveX control.
Impact of Workaround: Disabling the HTML Help ActiveX control prevents Internet Explorer from instantiating the control. This configuration causes program compatibility issues. Some examples of such issues are:
* In Help and Support Center, the Index feature no longer works.
* In HTML Help, features such as Related Topics and Shortcuts no longer work.
Features that are provided by the HTML Help control in Enterprise intranet programs no longer work.
FAQ for HTML Help ActiveX Control Vulnerability - CVE-2007-0214:
What is the scope of the vulnerability?
This vulnerability could allow remote code execution. If a user is logged on with administrative privileges, 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 privileges. Users whose accounts are configured to have fewer privileges on the system could be less impacted than users who operate with administrative privileges.
What causes the vulnerability?
HTML Help ActiveX control methods do not perform sufficient parameter validation.
What is HTML Help and HTML Help ActiveX control?
Microsoft HTML Help is the standard help system for the Windows platform. HTML Help ActiveX control is a program (Hhctrl.ocx) that is used to insert help navigation and secondary window functionality into an HTML file. HTML Help ActiveX control is designed to work with Internet Explorer and the Shdocvw.dll component. The Shdocvw.dll exposes interfaces to its host to allow it to be hosted separately as an ActiveX control. The Shdocvw.dll component is more frequently referred to as the WebBrowser Control. For more information about the HTML Help ActiveX control, see the product documentation and HTML HELP API support.
What are Internet Explorer security zones?
Internet Explorer security zones are part of a system that divides online content into categories or zones that are based on the trustworthiness of the content. Specific Web domains can be assigned to a zone, depending on how much you trust the content of each domain. The zone then restricts the capabilities of the Web content, based on the zone's policy. By default, most Internet domains are treated as part of the Internet zone. By default, the policy of the Internet zone prevents scripts and other active code from accessing resources on the local system.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could run arbitrary code on a users system. This could allow an attacker to take complete control of the affected system.
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 persuade a user to view the Web site. This can also include Web sites that accept user-provided content or advertisements, Web sites that host user-provided content or advertisements, and compromised Web sites. 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 persuade 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.
What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user view Web sites for any malicious action to occur. Therefore, any systems where Internet Explorer is used frequently, such as users workstations or terminal servers, are at the most risk from this vulnerability.
I am running Internet Explorer on 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. This mode sets the security level for the Internet zone to High. This is a mitigating factor for Web sites that have not been added to Internet Explorer Trusted sites zone. See the FAQ section of this security update for more information about Internet Explorer Enhanced Security Configuration.
What is the Internet Explorer Enhanced Security Configuration?
Internet Explorer Enhanced Security Configuration is a group of preconfigured Internet Explorer settings that reduce the likelihood of a user or of an administrator downloading and running specially crafted Web content on a server. Internet Explorer Enhanced Security Configuration reduces this risk by modifying many security-related settings. This includes the settings on the Security tab and the Advanced tab in the Internet Options dialog box. Some of the important modifications include the following:
* Security level for the Internet zone is set to High. This setting disables scripts, ActiveX controls, Microsoft Java Virtual Machine (MSJVM), and file downloads.
* Automatic detection of intranet sites is disabled. This setting assigns all intranet Web sites and all Universal Naming Convention (UNC) paths that are not explicitly listed in the Local intranet zone to the Internet zone.
* Install On Demand and non-Microsoft browser extensions are disabled. This setting prevents Web pages from automatically installing components and prevents non-Microsoft extensions from running.
* Multimedia content is disabled. This setting prevents music, animations, and video clips from running.
What does the update do?
The update removes the vulnerability by initializing parameters for HTML Help ActiveX control methods.
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. When the security bulletin was released, Microsoft had not received information that this vulnerability was being exploited.
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