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From:MICROSOFT <secure_(at)_microsoft.com>
Date:13.06.2006
Subject:Microsoft Security Bulletin MS06-030 Vulnerability in Server Message Block Could Allow Elevation of Privilege (914389)

Microsoft Security Bulletin MS06-030
Vulnerability in Server Message Block Could Allow Elevation of Privilege (914389)
Published: June 13, 2006

Version: 1.0
Summary

Who Should Read this Document: Customers who use Microsoft Windows

Impact of Vulnerability: Elevation of Privilege

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

Non-Affected Software:


Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and Microsoft Windows Millennium Edition (Me)
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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.
General Information

Executive Summary

Executive Summary:

This update resolves several newly discovered, privately reported vulnerability. Each vulnerability is documented in this bulletin in its own "Vulnerability Details" section of this bulletin.

We recommend that customers apply the update immediately

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

SMB Driver Elevation of Privilege Vulnerability - CVE-2006-2373


Elevation of Privilege


Important


Important


Important


Important


Important

SMB Invalid Handle Vulnerability - CVE-2006-2374


Denial of Service


Moderate


Moderate


Moderate


Moderate


Moderate

Aggregate Severity of All Vulnerabilities





Important


Important


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 Microsoft 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 Microsoft Windows XP Professional x64 Edition severity rating is the same as the (Comment: Validate which one) Windows Server 2003 Service Pack 1 OR Windows XP Service Pack 2 severity rating.


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


The Microsoft 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 Microsoft Windows Server 2003 x64 Edition severity rating is the same as the Windows Server 2003 Service Pack 1 severity rating.
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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 Service Pack 4 Windows XP Service Pack 1 Windows XP Service Pack 2 Windows Server 2003 Windows Server 2003 Service Pack 1

MS05-011


Replaced


Replaced


Replaced


Replaced


Not Applicable

Why does this update address several reported security vulnerabilities?
This update contains support for several vulnerabilities because the modifications that are required to address these issues are located in related files. Instead of having to install several updates that are almost the same, customers can install only this update.

Are Windows 98, Windows 98 Second Edition, or Windows Millennium Edition critically affected by one or more of the vulnerabilities that are addressed in this security bulletin?
No. Windows 98, Windows 98 Second Edition, and Windows Millennium Edition do not contain the affected component.

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 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 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.
Software 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 software that Microsoft Update and MBSA 2.0 currently do not detect, see Microsoft Knowledge Base Article 895660

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.
Software 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 software 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.
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Vulnerability Details

SMB Driver Elevation of Privilege Vulnerability - CVE-2006-2373

There is an elevation of privilege vulnerability in Server Message Block (SMB) that could allow an attacker who successfully exploited this vulnerability to take complete control of the affected system.

Mitigating Factors for SMB Driver Elevation of Privilege Vulnerability - CVE-2006-2373:


For an attack to be successful an attacker must have valid logon credentials and be able to log on locally to exploit this vulnerability.
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Workarounds for SMB Driver Elevation of Privilege Vulnerability - CVE-2006-2373:

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.

Note The following steps require Administrator privileges. In order to block the known attack vectors both of the recommended workarounds must be performed. We recommend that you restart the computer after you apply the workaround.


Disable the Workstation service

Disabling the Workstation service will help protect the affected system from attempts to exploit this vulnerability. To disable the Workstation service, follow these steps:

1.


Click Start, and then click Control Panel. Alternatively, point to Settings, and then click Control Panel.

2.


Double-click Administrative Tools.

3.


Double-click Services.

4.


Double-click Workstation.

5.


In the Startup type list, click Disabled.

6.


Click Stop, and then click OK.

You can also stop and disable the Workstation service by using the following command at the command prompt:

sc stop lanmanworkstation & sc config lanmanworkstation start= disabled

Impact of Workaround: If you disable the Workstation service, clients will not be able to access SMB shares.


Delete the MRxSmb driver registry entry

Deleting the MRxSmb registry entry will help protect the affected system from attempts to exploit this vulnerability. To delete the MRxSmb 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

1.


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

2.


Navigate to HKLM\System\CurrentControlSet\Services.

3.


Right click on the MRxSmb key and Export the key.

4.


Right click on the MRxSmb key and Delete the key.

Impact of Workaround: If you delete the MRxSmb registry key, clients will not be able to access SMB shares.
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FAQ for SMB Driver Elevation of Privilege Vulnerability - CVE-2006-2373:

What is the scope of the vulnerability?
This is an elevation of privilege vulnerability. 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.

What causes the vulnerability?
The vulnerability results because of the process that the affected operating systems use to validate certain SMB requests.

What is SMB?
Server Message Block (SMB), and its follow-on, Common Internet File System (CIFS), is the Internet Standard protocol that Windows uses to share files, printers, serial ports, and also to communicate between computers. To do this, SMB uses named pipes and mail slots. In a networked environment, servers make file systems and resources available to clients. Clients make SMB requests for resources. Servers make SMB responses. This is described as a client server, request-response protocol.

Does this vulnerability also affect CIFS?
Common Internet File System (CIFS) is an Internet Standard protocol. The vulnerability described here resides specifically in Microsoft's implementation of the protocol and not the protocol itself.

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

Who could exploit the vulnerability?
To try to exploit the vulnerability, an attacker must be able to log on locally to a system and run a program.

How could an attacker exploit the vulnerability?
To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability and gain complete control over the affected system.

What systems are primarily at risk from the vulnerability?
Microsoft Windows 2000, Windows XP and Windows Server 2003 that allow users to logon interactively including systems that function as Terminal Servers are primarily at risk from this vulnerability.

Are Windows 98, Windows 98 Second Edition or Windows Millennium Edition critically affected by this vulnerability?
No. Windows 98, Windows 98 Second Edition, and Windows Millennium Edition do not contain the affected component.

Could the vulnerability be exploited over the Internet?
No. An attacker must be able to log on to the specific system that is targeted for attack. An attacker cannot load and run a program remotely by using this vulnerability.

What does the update do?
The update addresses the vulnerability by modifying the way that the affected operating systems handle SMB related requests.

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.
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SMB Invalid Handle Vulnerability - CVE-2006-2374

There is denial of service vulnerability in Server Message Block (SMB) that could allow an attacker who successfully exploited this vulnerability to cause an affected system to stop responding.

Mitigating Factors for SMB Invalid Handle Vulnerability - CVE-2006-2374:


For an attack to be successful an attacker must have valid logon credentials and be able to log on locally to exploit this vulnerability.
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Workarounds for SMB Invalid Handle Vulnerability - CVE-2006-2374:

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.

Note The following steps require Administrator privileges. In order to block the known attack vectors both of the recommended workarounds must be performed. We recommend that you restart the computer after you apply this workaround.


Disable the Workstation service

Disabling the Workstation service will help protect the affected system from attempts to exploit this vulnerability. To disable the Workstation service, follow these steps:

1.


Click Start, and then click Control Panel. Alternatively, point to Settings, and then click Control Panel.

2.


Double-click Administrative Tools.

3.


Double-click Services.

4.


Double-click Workstation.

5.


In the Startup type list, click Disabled.

6.


Click Stop, and then click OK.

You can also stop and disable the Workstation service by using the following command at the command prompt:

sc stop lanmanworkstation & sc config lanmanworkstation start= disabled

Impact of Workaround: If you disable the Workstation service, clients will not be able to access SMB shares.


Delete the MRxSmb driver registry entry

Deleting the MRxSmb registry entry will help protect the affected system from attempts to exploit this vulnerability. To delete the MRxSmb 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

1.


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

2.


Navigate to HKLM\System\CurrentControlSet\Services.

3.


Right click on the MRxSmb key and Export the key.

4.


Right click on the MRxSmb key and Delete the key.

Impact of Workaround: If you delete the MRxSmb registry key, clients will not be able to access SMB shares.
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FAQ for SMB Invalid Handle Vulnerability - CVE-2006-2374:

What is the scope of the vulnerability?
This is a denial of service vulnerability. An attacker who exploited this vulnerability could cause the affected system to stop responding. During that time, the affected system cannot respond to requests. Note that the denial of service vulnerability would not allow an attacker to execute code or to elevate their user rights, but it could cause the affected system to stop responding.

What causes the vulnerability?
The vulnerability results because of the process that the affected operating systems use to validate certain SMB requests.

What is SMB?
Server Message Block (SMB), and its follow-on, Common Internet File System (CIFS), is the Internet Standard protocol that Windows uses to share files, printers, serial ports, and also to communicate between computers. To do this, SMB uses named pipes and mail slots. In a networked environment, servers make file systems and resources available to clients. Clients make SMB requests for resources. Servers make SMB responses. This is described as a client server, request-response protocol.

Does this vulnerability also affect CIFS?
Common Internet File System (CIFS) is an Internet Standard protocol. The vulnerability described here resides specifically in Microsoft's implementation of the protocol and not the protocol itself.

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

Who could exploit the vulnerability?
To try to exploit the vulnerability, an attacker must be able to log on locally to a system and run a program.

How could an attacker exploit the vulnerability?
To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability and gain complete control over the affected system.

What systems are primarily at risk from the vulnerability?
Microsoft Windows 2000, Windows XP and Windows Server 2003 that allow users to logon interactively including systems that function as Terminal Servers are primarily at risk from this vulnerability.

Are Windows 98, Windows 98 Second Edition or Windows Millennium Edition critically affected by this vulnerability?
No. Windows 98, Windows 98 Second Edition, and Windows Millennium Edition do not contain the affected component.

Could the vulnerability be exploited over the Internet?
No. An attacker must be able to log on to the specific system that is targeted for attack. An attacker cannot load and run a program remotely by using this vulnerability.

What does the update do?
The update addresses the vulnerability by modifying the way that the affected operating systems handle SMB related requests.

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:


iDEFENSE for reporting the SMB Elevation of Privilege Vulnerability - CVE-2006-2373


iDEFENSE for reporting the SMB Invalid Handle Vulnerability - CVE-2006-2374

Revisions:


V1.0 (June 13, 2006): Bulletin published.

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