Microsoft Security Bulletin MS08-006 – Important Vulnerability in Internet Information Services Could Allow Remote Code Execution (942830)

Microsoft Security Bulletin MS08-006 – Important
Vulnerability in Internet Information Services Could Allow Remote Code Execution (942830)
Published: February 12, 2008

Version: 1.0
General Information
Executive Summary

This important update resolves a privately reported vulnerability in Internet Information Services (IIS). A remote code execution vulnerability exists in the way that IIS handles input to ASP Web pages. An attacker who successfully exploited this vulnerability could then perform actions on the IIS server with the same rights as the Worker Process Identity (WPI). The WPI is configured with Network Service account privileges by default. IIS servers with ASP pages whose application pools are configured with a WPI that uses an account with administrative privileges could be more seriously impacted than IIS servers whose application pool is configured with the default WPI settings.

The security update is rated important for Microsoft Internet Information Services on all supported editions of Windows XP and Windows Server 2003. For more information, see the subsection, Affected and Non-Affected Software, in this section.

For more information about these vulnerabilities, see the Frequently Asked Questions (FAQ) subsection under the next section, Vulnerability Information.

Recommendation. Microsoft recommends that customers apply the update at the earliest opportunity.

Known Issues. None
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Affected and Non-Affected Software

The following software 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 Aggregate Severity Rating Bulletins Replaced by this Update

Windows XP Professional Service Pack 2

Microsoft Internet Information Services 5.1

Remote Code Execution

Important

MS06-034

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

Microsoft Internet Information Services 6.0

Remote Code Execution

Important

MS06-034

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

Microsoft Internet Information Services 6.0

Remote Code Execution

Important

MS06-034

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

Microsoft Internet Information Services 6.0

Remote Code Execution

Important

MS06-034

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

Microsoft Internet Information Services 6.0

Remote Code Execution

Important

MS06-034

Non-Affected Software
Operating System

Microsoft Windows 2000 Service Pack 4

Windows Vista

Windows Vista x64 Edition

Windows Vista Service Pack 1 (all editions)

Windows Server 2008 (all editions)

Note Supported editions of Windows Small Business Server 2003 contain the same affected code as Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2. However, for the ASP Vulnerability (CVE-2008-0075), default configurations of Windows Small Business Server 2003 have a greater exposure to the same vulnerability and therefore merit a severity rating of Critical.
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Frequently Asked Questions (FAQ) Related to This Security Update

I am using an older version 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 versions or editions are affected. Other versions or editions are past their support life cycle. To determine the support life cycle for your software version or edition, visit Microsoft Support Lifecycle.

It should be a priority for customers who have older versions or editions of the software to migrate to supported versions or editions to prevent potential exposure to vulnerabilities. For more information about the Windows Product Lifecycle, visit Microsoft Support Lifecycle. For more information about the extended security update support period for these software versions or editions, visit Microsoft Product Support Services.

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 Microsoft Worldwide Information, 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 ASP Vulnerability - CVE-2008-0075 Aggregate Severity Rating

Microsoft Internet Information Services 5.1 on Windows XP Professional Service Pack 2

Important
Remote Code Execution

Important

Microsoft Internet Information Services 6.0 on Windows XP Professional x64 Edition and Windows XP Professional x64 Edition Service Pack 2

Important
Remote Code Execution

Important

Microsoft Internet Information Services (IIS) 6.0 on Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2

Important
Remote Code Execution

Important

Microsoft Internet Information Services (IIS) 6.0 on Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Important
Remote Code Execution

Important

Microsoft Internet Information Services (IIS) 6.0 on Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems

Important
Remote Code Execution

Important
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ASP Vulnerability - CVE-2008-0075

A remote code execution vulnerability exists in the way that Internet Information Services handles input to ASP Web pages. An attacker could exploit the vulnerability by passing malicious input to a Web site’s ASP page. An attacker who successfully exploited this vulnerability could then perform any actions on the IIS Server with the same rights as the Worker Process Identity (WPI), which by default is configured with Network Service account privileges.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-0075.

Mitigating Factors for ASP Vulnerability - CVE-2008-0075

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:
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IIS 5.1 is not part of a default install of Windows XP Professional Service Pack 2.
•

On supported editions of Windows Server 2003, IIS is not installed or enabled by default.
•

On supported editions of Windows Server 2003, if IIS is enabled, classic ASP is not installed or enabled by default.
•

On supported editions of Windows Server 2003, if IIS is enabled and classic ASP is used, an attacker who successfully exploited this vulnerability could only obtain Network Service account privileges by default. By default, Network Service account privileges have the same user rights as an authenticated user.
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ASP.NET is not affected by this vulnerability. Customers who have only ASP.NET installed and not ASP are not at risk from this vulnerability.
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Workarounds for ASP Vulnerability - CVE-2008-0075

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:
•

On Windows Server 2003, disable classic ASP

To disable classic ASP, follow these steps:

1.Click Start, click Administrative Tools, and then click Internet Information Services (IIS) Manager.

2.Click the plus sign (+) next to the server’s name and then click the Web Service Extensions folder.

3.Click to highlight Active Server Pages in the right pane and then click Prohibit.

Impact of workaround.Users will be unable to use classic ASP pages.

How to undo the workaround.To undo the workaround, follow steps 1 through 3 above and click Allow when highlighting Active Server Pages.
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FAQ for ASP Vulnerability - CVE-2008-0075

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could then perform actions on the IIS server with the same rights as the Worker Process Identity (WPI), which by default is configured with Network Service account privileges.

What causes the vulnerability?
The vulnerability is caused by the way that Internet Information Services incorrectly processes input to ASP pages.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could then perform actions on the IIS Server with the same rights as the Worker Process Identity (WPI), which is configured with Network Service account privileges by default. Services configured with Network Service account privileges obtain authenticated user level access, not administrative level access. For more information see NetworkService Account. IIS servers whose application pool is configured with a WPI that uses an account with administrative privileges could be more seriously impacted than IIS servers whose application pool is configured with the default WPI settings.

The Network Service account uses the computer's credentials when it authenticates remotely, but has a greatly reduced privilege level on the server itself and, therefore, does not have local administrator privileges. For more information see NetworkService Account, IIS and Built-in Accounts (IIS 6.0), Configuring Worker Process Identities (IIS 6.0), and Configuring Application Pools in IIS 6.0 (IIS 6.0).

How could an attacker exploit the vulnerability?
An attacker could pass specially crafted input to an ASP page. The ASP page could already exist or could be uploaded by a user in a hosted environment.

What are worker processes for IIS?
Worker processes are processes that execute the server-side processing tasks for a web server. For information on worker processes and how they are implemented in IIS 6.0 see Worker Processes (IIS 6.0). Additional information on worker processes and how they execute Web-based applications in isolation see Worker Process Isolation Mode (IIS 6.0).

What is ASP?
Microsoft Active Server Pages (ASP) is a server-side scripting technology that can be used to create dynamic and interactive Web applications. An ASP page is an HTML page that contains server-side scripts that are processed by the Web server before being sent to the user's browser.

What systems are primarily at risk from the vulnerability?
Windows Server 2003 Web servers are at risk if IIS and ASP are enabled. Web hosting providers that allow their customers to upload ASP pages to their hosted Web sites are at increased risk.

What does the update do?
The update removes the vulnerability by changing the way that Internet Information Services processes input to ASP pages.

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.

Other Information
Support
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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.
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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.
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Revisions
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V1.0 (February 12, 2008) Bulletin published.