Lucene search

K
securityvulnsSecurityvulnsSECURITYVULNS:DOC:13799
HistoryAug 09, 2006 - 12:00 a.m.

Microsoft Security Bulletin MS06-050 Vulnerabilities in Microsoft Windows Hyperlink Object Library Could Allow Remote Code Execution (920670)

2006-08-0900:00:00
vulners.com
23

Microsoft Security Bulletin MS06-050
Vulnerabilities in Microsoft Windows Hyperlink Object Library Could Allow Remote Code Execution (920670)
Published: August 8, 2006

Version: 1.0
Summary

Who Should Read this Document: Customers who use Microsoft Windows

Impact of Vulnerability: Remote Code Execution

Maximum Severity Rating: Important

Recommendation: Customers should apply the update at the earliest opportunity

Security Update Replacement: This bulletin replaces a prior security update. See the frequently asked questions (FAQ) section of this bulletin for the complete list.

Caveats: None

Tested Software and Security Update Download Locations:

Affected Software:

Microsoft Windows 2000 Service Pack 4— Download the update

Microsoft Windows XP Service Pack 1 and 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

The software in this list has been tested to determine whether the versions are affected. Other versions either no longer include security update support or may not be affected. To determine the support life cycle for your product and version, visit the Microsoft Support Lifecycle Web site.

Note The security updates for Microsoft Windows Server 2003, Windows Server 2003 Service Pack 1, and Windows Server 2003 x64 Edition also apply to Windows Server 2003 R2.
Top of sectionTop of section
General Information

Executive Summary

Executive Summary:

This update resolves two newly discovered vulnerabilities. Each vulnerability is documented in its own subsection in the "Vulnerability Details" section of this bulletin.

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.

User interaction is required for an attacker to exploit these vulnerabilities.

We recommend that customers apply the update at the earliest opportunity.

Severity Ratings and Vulnerability Identifiers:
Vulnerability Identifiers Impact of Vulnerability Windows 2000 Service Pack 4 Windows XP Service Pack 1 and Windows XP Service Pack 2 Windows Server 2003 and Windows Server 2003 Service Pack 1

Hyperlink Object Buffer Overflow Vulnerability - CVE-2006-3086

Remote Code Execution

Important

Important

Important

Hyperlink Object Function Vulnerability - CVE-2006-3438

Remote Code Execution

Important

Important

Important

Aggregate severity of all vulnerabilities

Important

Important

Important

This assessment is based on the types of systems that are affected by the vulnerability, their typical deployment patterns, and the effect that exploiting the vulnerability would have on them.

Note The security updates for Windows Server 2003, Windows Server 2003 Service Pack 1, and Windows Server 2003 x64 Edition also apply to Windows Server 2003 R2.

Note The severity ratings for non-x86 operating system versions map to the x86 operating systems versions as follows:

The Windows XP Professional x64 Edition severity rating is the same as the Windows XP Service Pack 2 severity rating.

The Windows Server 2003 for Itanium-based Systems severity rating is the same as the Windows Server 2003 severity rating.

The Windows Server 2003 with SP1 for Itanium-based Systems severity rating is the same as the Windows Server 2003 Service Pack 1 severity rating.

The Windows Server 2003 x64 Edition severity rating is the same as the Windows Server 2003 Service Pack 1 severity rating.
Top of sectionTop of section

Frequently Asked Questions (FAQ) Related to This Security Update

What updates does this release replace?
This security update replaces a prior security update. The security bulletin ID and affected operating systems are listed in the following table.
Bulletin ID Windows 2000 Windows XP Service Pack 1 and Windows XP Service Pack 2 Windows Server 2003 Windows Server 2003 Service Pack 1

MS05-015

Replaced

Replaced

Replaced

Not Applicable

Extended security update support for Windows 98, Windows 98 Second Edition, or Windows Millennium Edition ended on July 11, 2006. I am still using one of these operating systems, what should I do?
Windows 98, Windows 98 Second Edition, and Windows Millennium Editionhave reached the end of their support life cycles. It should be a priority for customers who have these operating system versions to migrate to supported versions to prevent potential exposure to vulnerabilities. For more information about the Windows Product Support Lifecycle, visit the following Microsoft Support Lifecycle Web site. For more information about the extended security update support period for these operating system versions, visit the Microsoft Product Support Services Web site.

Extended security update support for Microsoft Windows NT Workstation 4.0 Service Pack 6a and Windows 2000 Service Pack 2 ended on June 30, 2004. Extended security update support for Microsoft Windows NT Server 4.0 Service Pack 6a ended on December 31, 2004. Extended security update support for Microsoft Windows 2000 Service Pack 3 ended on June 30, 2005. I am still using one of these operating systems, what should I do?
Windows NT Workstation 4.0 Service Pack 6a, Windows NT Server 4.0 Service Pack 6a, Windows 2000 Service Pack 2, and Windows 2000 Service Pack 3 have reached the end of their support life cycles. It should be a priority for customers who have these operating system versions to migrate to supported versions to prevent potential exposure to vulnerabilities. For more information about the Windows Product Support Lifecycle, visit the following Microsoft Support Lifecycle Web site. For more information about the extended security update support period for these operating system versions, visit the Microsoft Product Support Services Web site.

Customers who require custom support for these products 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.

Can I use the Microsoft Baseline Security Analyzer (MBSA) to determine whether this update is required?
The following table provides the MBSA detection summary for this security update.
Product MBSA 1.2.1 MBSA 2.0

Microsoft Windows 2000 Service Pack 4

Yes

Yes

Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service Pack 2

Yes

Yes

Microsoft Windows XP Professional x64 Edition

No

Yes

Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1

Yes

Yes

Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft Windows Server 2003 with Service Pack 1 for Itanium-based Systems

No

Yes

Microsoft Windows Server 2003 x64 Edition family

No

Yes

For more information about MBSA, visit the MBSA Web site. For more information about the programs that Microsoft Update and MBSA 2.0 currently do not detect, see Microsoft Knowledge Base Article 895660.

For more detailed information, see Microsoft Knowledge Base Article 910723.

Can I use Systems Management Server (SMS) to determine whether this update is required?
The following table provides the SMS detection summary for this security update.
Product SMS 2.0 SMS 2003

Microsoft Windows 2000 Service Pack 4

Yes

Yes

Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service Pack 2

Yes

Yes

Microsoft Windows XP Professional x64 Edition

No

Yes

Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1

Yes

Yes

Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft Windows Server 2003 with Service Pack 1 for Itanium-based Systems

No

Yes

Microsoft Windows Server 2003 x64 Edition family

No

Yes

SMS uses MBSA for detection. Therefore, SMS has the same limitation that is listed earlier in this bulletin related to programs that MBSA does not detect.

For SMS 2.0, the SMS SUS Feature Pack, which includes the Security Update Inventory Tool, can be used by SMS to detect security updates. SMS SUIT uses the MBSA 1.2.1 engine for detection. For more information about the Security Update Inventory Tool, visit the following Microsoft Web site. For more information about the limitations of the Security Update Inventory Tool, see Microsoft Knowledge Base Article 306460. The SMS SUS Feature Pack also includes the Microsoft Office Inventory Tool to detect required updates for Microsoft Office applications.

For SMS 2003, the SMS 2003 Inventory Tool for Microsoft Updates can be used by SMS to detect security updates that are offered by Microsoft Update and that are supported by Windows Server Update Services. For more information about the SMS 2003 Inventory Tool for Microsoft Updates, visit the following Microsoft Web site. SMS 2003 can also use the Microsoft Office Inventory Tool to detect required updates for Microsoft Office applications.

For more information about SMS, visit the SMS Web site.

For more detailed information, see Microsoft Knowledge Base Article 910723.
Top of sectionTop of section

Vulnerability Details

Hyperlink COM Object Buffer Overflow Vulnerability - CVE-2006-3086:

A remote code execution vulnerability exists in the Hyperlink Object Library. This problem exists because of an unchecked buffer in the code that is used for handling hyperlinks. An attacker could exploit the vulnerability by constructing a malicious hyperlink which could potentially lead to remote code execution if a user clicks a malicious link within an Office file or e-mail message. An attacker who successfully exploited this vulnerability could take complete control of the affected system. User interaction is required to exploit this vulnerability.

Mitigating Factors for Hyperlink COM Object Buffer Overflow Vulnerability - CVE-2006-3086:

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.

The vulnerability could not be exploited automatically through e-mail. For an attack to be successful an attacker must persuade a user to click a link in e-mail message or open an Office file and click a link within that file.
Top of sectionTop of section

Workarounds for Hyperlink COM Object Buffer Overflow Vulnerability - CVE-2006-3086:

Microsoft has tested the following workarounds. Although these workarounds will not correct the underlying vulnerability, they help block known attack vectors. A workaround may not block all attack vectors. When a workaround reduces functionality, it is identified in the following section.

Modify the Access Control List to deny access to Hlink.dll for all users
Disabling the Hlink.dll registry key helps protect the affected system from attempts to exploit this vulnerability. To modify the Hlink.dll registry key:

Click Start, click Run, type cacls "%windir%\system32\hlink.dll" /d everyone (without the quotation marks), and then click OK.

Impact of Workaround: Users of Office applications will not be able to edit hyperlinks or click on hyperlinks embedded in Office documents.

Modify the Access Control List to disable the HLINK registry key
Modifying the Access Control List on the “HLINK” registry key helps protect the affected system from attempts to exploit this vulnerability. To modify the registry key, follow these steps.

Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe.

Note We recommend backing up the registry before you edit it.

For Windows 2000

Note Make a note of the permissions that are listed in the dialog box so that you can restore them to their original values at a later time

Click Start, click Run, type "regedt32" (without the quotation marks), and then click OK.

Expand HKEY_CLASSES_ROOT, expand CLSID, and then click {79eac9d0-baf9-11ce-8c82-00aa004ba90b}.

Click Security, and then click Permissions.

Click to clear the Allow Inheritable Permissions from the parent to propagate to this object check box. You are prompted to click Copy, Remove, or Cancel. Click Remove, and then click OK.

You receive a message that states that no one will be able to access this registry key. Click Yes when you are prompted to do so.

For Windows XP Service Pack 1 or later operating systems

Note Make a note of the permissions that are listed in the dialog box so that you can restore them to their original values at a later time

Click Start, click Run, type "regedit" (without the quotation marks), and then click OK.

Expand HKEY_CLASSES_ROOT, expand CLSID, and then click {79eac9d0-baf9-11ce-8c82-00aa004ba90b}.

Click Edit, and then click Permissions.

Click Advanced.

Click to clear the Inherit from parent the permission entries that apply to child objects. Include these with entries explicitly defined here. check box. You are prompted to click Copy, Remove, or Cancel. Click Remove, and then check OK.

You receive a message that states that no one will be able to access this registry key. Click Yes, and then click OK to close the Permissions for {79eac9d0-baf9-11ce-8c82-00aa004ba90b} dialog box.

Impact of Workaround: Users of Office applications will not be able to edit hyperlinks or click on hyperlinks embedded in Office documents.

Read e-mail messages in plain text format if you are using Outlook 2002 or a later version, or Outlook Express 6 SP1 or a later version, to help protect yourself from the HTML e-mail attack vector.

Microsoft Outlook 2002 users who have applied Office XP Service Pack 1 or a later version and Microsoft Outlook Express 6 users who have applied Internet Explorer 6 Service Pack 1 or a later version can enable this setting and view e-mail messages that are not digitally signed or e-mail messages that are not encrypted in plain text only.

For information about this setting in Outlook Express 6, see Microsoft Knowledge Base Article 291387.

Impact of Workaround: E-mail messages that are viewed in plain text format will not contain pictures, specialized fonts, animations, or other rich content. Additionally:

The changes are applied to the preview pane and to open messages.

Pictures become attachments so that they are not lost.

Because the message is still in Rich Text or HTML format in the store, the object model (custom code solutions) may behave unexpectedly.

Do not click on hyperlinks in Microsoft Office documents from untrusted sources.
Top of sectionTop of section

FAQ for Hyperlink COM Object Buffer Overflow Vulnerability - CVE-2006-3086:

What is the scope of the vulnerability?
A remote code execution vulnerability exists in the Hyperlink Object Library. This problem exists because of an unchecked buffer in the code that is used for handling hyperlinks. An attacker could exploit the vulnerability by constructing a malicious hyperlink which could potentially lead to remote code execution if a user clicks a malicious link within an Office file or e-mail message. An attacker who successfully exploited this vulnerability could take complete control of the affected system. User interaction is required to exploit this vulnerability.

If a user were 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 affected than users who operate with administrative user rights.

What causes the vulnerability?
An unchecked buffer in the Hyperlink Object Library.

What is the Hyperlink Object Library?
The Hyperlink Object Library is a collection of application programming interfaces. These interfaces provide functionality to software developers for handling hyperlinks. For more information about hyperlinks, see the product documentation.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take complete control of the affected system.

How could an attacker exploit the vulnerability?
The vulnerability could not be exploited automatically through e-mail. For an attack to be successful an attacker must persuade a user to click a link in e-mail message or open an Office file and click a link within that file.

What systems are primarily at risk from the vulnerability?
Workstations and terminal servers are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

What does the update do?
The update removes the vulnerability by modifying the way that the Hyperlink Object Library validates the length of a message before it passes the message to the allocated buffer.

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-2006-3086. This security bulletin addresses the privately and publicly disclosed vulnerability as well as additional issues discovered through internal investigations.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had seen examples of proof of concept code published publicly but had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

Does applying this security update help protect customers from the code that has been published publicly that attempts to exploit this vulnerability?
Yes. This security update addresses the vulnerability that potentially could be exploited by using the published proof of concept code. The vulnerability that has been addressed has been assigned the Common Vulnerability and Exposure number CVE-2006-3086.
Top of sectionTop of section
Top of sectionTop of section

Hyperlink Object Function Vulnerability - CVE-2006-3438:

A remote code execution vulnerability exists in the Hyperlink Object Library. This problem exists when the Hyperlink Object Library uses a file containing a malformed function while handling hyperlinks. An attacker could exploit the vulnerability by constructing a malicious hyperlink which could potentially lead to remote code execution if a user clicks a malicious link within an Office file, or e-mail message. An attacker who successfully exploited this vulnerability could take complete control of the affected system. User interaction is required to exploit this vulnerability.

Mitigating Factors for Hyperlink Object Function Vulnerability - CVE-2006-3438:

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.

The vulnerability could not be exploited automatically through e-mail. For an attack to be successful an attacker must persuade a user to click a link in e-mail message or open an Office file and click a link within that file.
Top of sectionTop of section

Workarounds for Hyperlink Object Function Vulnerability - CVE-2006-3438:

Microsoft has tested the following workarounds. Although these workarounds will not correct the underlying vulnerability, they help block known attack vectors. A workaround may not block all attack vectors. When a workaround reduces functionality, it is identified in the following section.

Modify the Access Control List to deny access to Hlink.dll for all users
Disabling the Hlink.dll registry key helps protect the affected system from attempts to exploit this vulnerability. To modify the Hlink.dll registry key:

Click Start, click Run, type cacls "%windir%\system32\hlink.dll" /d everyone (without the quotation marks), and then click OK.

Impact of Workaround: Users of Office applications will not be able to edit hyperlinks or click on hyperlinks embedded in Office documents.

Modify the Access Control List to disable the HLINK registry key
Modifying the Access Control List on the “HLINK” registry key helps protect the affected system from attempts to exploit this vulnerability. To modify the registry key, follow these steps.

Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe.

Note We recommend backing up the registry before you edit it.

For Windows 2000

Note Make a note of the permissions that are listed in the dialog box so that you can restore them to their original values at a later time

Click Start, click Run, type "regedt32" (without the quotation marks), and then click OK.

Expand HKEY_CLASSES_ROOT, expand CLSID, and then click {79eac9d0-baf9-11ce-8c82-00aa004ba90b}.

Click Security, and then click Permissions.

Click to clear the Allow Inheritable Permissions from the parent to propagate to this object check box. You are prompted to click Copy, Remove, or Cancel. Click Remove, and then click OK.

You receive a message that states that no one will be able to access this registry key. Click Yes when you are prompted to do so.

For Windows XP Service Pack 1 or later operating systems

Note Make a note of the permissions that are listed in the dialog box so that you can restore them to their original values at a later time

Click Start, click Run, type "regedit" (without the quotation marks), and then click OK.

Expand HKEY_CLASSES_ROOT, expand CLSID, and then click {79eac9d0-baf9-11ce-8c82-00aa004ba90b}.

Click Edit, and then click Permissions.

Click Advanced.

Click to clear the Inherit from parent the permission entries that apply to child objects. Include these with entries explicitly defined here. check box. You are prompted to click Copy, Remove, or Cancel. Click Remove, and then check OK.

You receive a message that states that no one will be able to access this registry key. Click Yes, and then click OK to close the Permissions for {79eac9d0-baf9-11ce-8c82-00aa004ba90b} dialog box.

Impact of Workaround: Users of Office applications will not be able to edit hyperlinks or click on hyperlinks embedded in Office documents.

Read e-mail messages in plain text format if you are using Outlook 2002 or a later version, or Outlook Express 6 SP1 or a later version, to help protect yourself from the HTML e-mail attack vector.

Microsoft Outlook 2002 users who have applied Office XP Service Pack 1 or a later version and Microsoft Outlook Express 6 users who have applied Internet Explorer 6 Service Pack 1 or a later version can enable this setting and view e-mail messages that are not digitally signed or e-mail messages that are not encrypted in plain text only.

For information about this setting in Outlook Express 6, see Microsoft Knowledge Base Article 291387.

Impact of Workaround: E-mail messages that are viewed in plain text format will not contain pictures, specialized fonts, animations, or other rich content. Additionally:

The changes are applied to the preview pane and to open messages.

Pictures become attachments so that they are not lost.

Because the message is still in Rich Text or HTML format in the store, the object model (custom code solutions) may behave unexpectedly.

Do not click on hyperlinks in Microsoft Office documents from untrusted sources.
Top of sectionTop of section

FAQ for Hyperlink Object Function Vulnerability - CVE-2006-3438:

What is the scope of the vulnerability?
A remote code execution vulnerability exists in the Hyperlink Object Library. This problem exists when the Hyperlink Object Library uses a file containing a malformed function while handling hyperlinks. An attacker could exploit the vulnerability by constructing a malicious hyperlink which could potentially lead to remote code execution if a user clicks a malicious link within an Office file, or e-mail message. An attacker who successfully exploited this vulnerability could take complete control of the affected system. User interaction is required to exploit this vulnerability.

If a user were 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 affected than users who operate with administrative user rights.

What causes the vulnerability?
An unchecked buffer in the Hyperlink Object Library.

What is the Hyperlink Object Library?
The Hyperlink Object Library is a collection of application programming interfaces. These interfaces which provide functionality to software developers for handling hyperlinks. For more information about hyperlinks, see the product documentation.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take complete control of the affected system.

How could an attacker exploit the vulnerability?
The vulnerability could not be exploited automatically through e-mail. For an attack to be successful an attacker must persuade a user to click a link in e-mail message or open an Office file and click a link within that file.

What systems are primarily at risk from the vulnerability?
Workstations and terminal servers are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

What does the update do?
The update removes the vulnerability by modifying the way that the Hyperlink Object Library validates the length of a message before it passes the message to the allocated buffer.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure. Microsoft had not received any information to indicate that this vulnerability had been publicly disclosed when this security bulletin was originally issued.

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.

Acknowledgments

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

Pedram Amini of the TippingPoint Security Research Team for reporting the Hyperlink Object Buffer Overflow Vulnerability - CVE-2006-3086.

Steve Tai of CSC Australia Pty Limited for reporting the Hyperlink Object Function Vulnerability - CVE-2006-3438.

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 (August 8, 2006): Bulletin published.

Related for SECURITYVULNS:DOC:13799