Microsoft Security Bulletin MS07-041 - Important Vulnerability in Microsoft Internet Information Services Could Allow Remote Code Execution (939373)

Microsoft Security Bulletin MS07-041 - Important
Vulnerability in Microsoft Internet Information Services Could Allow Remote Code Execution (939373)
Published: July 10, 2007

Version: 1.0
General Information
Executive Summary

This important security update resolves a privately reported vulnerability. This vulnerability could allow remote code execution if an attacker sent specially crafted URL requests to a Web page hosted by Internet Information Services (IIS) 5.1 on Windows XP Professional Service Pack 2. IIS 5.1 is not part of a default install of Windows XP Professional Service Pack 2. An attacker who successfully exploited this vulnerability could take complete control of the affected system.

This is an important security update for all supported 32-bit editions of Windows XP Service Pack 2. For more information, see the subsection, Affected and Non-Affected Software, in this section.

This security update addresses the vulnerability by adding a check on memory requests within Internet Information Services. 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: Microsoft recommends that customers apply the update immediately.

Known Issues: Microsoft Knowledge Base Article 939373 documents the currently known issues that customers may experience when they install this security update. The article also documents recommended solutions for these issues.
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Affected and Non-Affected Software

In the following tables of affected and non-affected software, software editions that are not listed are past their support lifecycle. To determine the support lifecycle for your product and edition, visit Microsoft Support Lifecycle.

Affected Software
Software Component Maximum Security Impact Aggregate Severity Rating Bulletins Replaced By This Update

Windows XP Professional Service Pack 2

Microsoft Internet Information Services (IIS) 5.1

Remote Code Execution

Important

None

Non-Affected Software
Operating System

Windows 2000 Service Pack 4

Windows XP Home Service Pack 2

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

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

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

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

Windows Vista

Windows Vista x64 Edition
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Frequently Asked Questions (FAQ) Related to This Security Update

I am using an older edition of the software discussed in this security bulletin. What should I do?
Theaffected software listed in this bulletin has been tested to determine which editions are affected. Other editions are past their support life cycle. To determine the support life cycle for your product and edition, visit Microsoft Support Lifecycle.

It should be a priority for customers who have older editions of the software to migrate to supported editions 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 operating system editions, 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 IIS Memory Request Vulnerability - CVE-2005-4360 Aggregate Severity Rating

Windows XP Professional Service Pack 2

Important

Remote Code Execution

Important
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IIS Memory Request Vulnerability - CVE-2005-4360

There is a remote code execution vulnerability in Internet Information Services (IIS) 5.1 on Windows XP Professional Service Pack 2 that could allow an attacker who successfully exploited this vulnerability to take complete control of the affected system. An attacker could exploit the vulnerability by sending specially crafted URL requests to a Web page hosted by Internet Information Services.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2005-4360.

Mitigating Factors for IIS Memory Request Vulnerability - CVE-2005-4360

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:
•

IIS 5.1 is not part of a default install of Windows XP Professional Service Pack 2.
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Workarounds for IIS Memory Request Vulnerability - CVE-2005-4360

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. It is recommended that customers use versions of IIS included in server editions of Windows and use the version of IIS included in Windows XP Professional Service Pack 2 for development and testing of Web sites and Web pages.
•

Use URLScan 2.5
The installation of URLScan helps protect the affected system from attempts to exploit this vulnerability.

Install URLScan, using the default URLScan.ini settings.

Restart the IISAdmin and WWW Publishing services for the changes to take effect.
•

To help protect from network-based attempts to exploit this vulnerability, block access to port 80 (TCP) using:
•

Windows Firewall.
•

Internet Protocol security (IPSec). Detailed information about IPSec and about how to apply filters is available in Microsoft Knowledge Base Article 313190 and Microsoft Knowledge Base Article 813878.

Additional ports where Web content is hosted by IIS should also be blocked.
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FAQ for IIS Memory Request Vulnerability - CVE-2005-4360:

What is the scope of the vulnerability?
If successfully exploited, this remote code execution vulnerability could allow the attacker to run arbitrary code within the context of the local system account.

What causes the vulnerability?
An unchecked buffer in the Internet Information Services 5.1 URL parser.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take complete control of the affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

How could an attacker exploit the vulnerability?
An attacker could send specially crafted URL requests to a Web site hosted by IIS 5.1 on Windows XP Professional Service Pack 2.

What systems are primarily at risk from the vulnerability?
Windows XP Professional systems running IIS 5.1 are at risk from this vulnerability only when IIS is installed and started.

What does the update do?
The update removes the vulnerability by validating the memory request within IIS.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
While this vulnerability originally was publicly disclosed as a denial of service, additional information has recently been privately reported to Microsoft as a remote code execution vulnerability. When it was understood as a denial of service in a non-default install of Windows XP Professional Service Pack 2 it was determined that the appropriate servicing method was in a service pack. Since it is now understood to be exploitable we are addressing this with a security bulletin.

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:

Jonathan Afek and Adi Sharabani of Watchfire for working with Microsoft and supplying additional information about the IIS Memory Request Vulnerability (CVE-2005-4360).

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
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V1.0 (July 10, 2007): Bulletin published.