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  Microsoft Windows Client Service for Netware multiple vulnerabilities

  [Full-disclosure] Vulnerabilities in Client Service for NetWare

From:MICROSOFT <secure_(at)_microsoft.com>
Date:14.11.2006
Subject:Microsoft Security Bulletin MS06-066 Vulnerabilities in Client Service for NetWare Could Allow Remote Code Execution (923980)

Microsoft Security Bulletin MS06-066
Vulnerabilities in Client Service for NetWare Could Allow Remote Code Execution (923980)
Published: November 14, 2006

Version: 1.0
Summary

Who Should Read this Document: Customers who use Microsoft Windows

Impact of Vulnerabilities: 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 2 — Download the update


Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1 — Download the update

Non-Affected Software:


Microsoft Windows XP Professional x64 Edition


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


Microsoft Windows Server 2003 x64 Edition


Windows Vista

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.
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General Information

Executive Summary

Executive Summary:

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

The Client Service for NetWare is also called the Gateway Service for NetWare on Windows 2000 Server.

On vulnerable versions of Microsoft Windows, an attacker who successfully exploited these vulnerabilities could remotely take complete control of the client workstation. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

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

Microsoft Client Service for NetWare Memory Corruption Vulnerability - CVE-2006-4688


Remote Code Execution


Important


Important


Moderate

NetWare Driver Denial of Service Vulnerability - CVE-2006-4689


Denial of Service


Moderate


Moderate


Low

Aggregate Severity of All Vulnerabilities





Important


Important


Moderate

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.
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Frequently Asked Questions (FAQ) Related to This Security Update

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.

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

MS05-046


Not Replaced


Replaced


Not Replaced

Extended security update support for Microsoft 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 Edition 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 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 XP Home Edition Service Pack 1 or Service Pack 1a, Windows XP Media Center Edition 2002 Service Pack 1, Windows XP Media Center Edition 2004 Service Pack 1, Windows XP Professional Service Pack 1 or Service Pack 1a, and Windows XP Tablet PC Edition Service Pack 1 ended on October 10, 2006. I am still using one of these operating systems; what should I do?
Windows XP (all versions) Service Pack 1 has reached the end of its support life cycle. 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.

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 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.

For more information, visit the Windows Operating System 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 2


Yes


Yes

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


Yes


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 2


Yes


Yes

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


Yes


Yes

SMS 2.0 and SMS 2003 Software Updates Feature Pack can use MBSA 1.2.1 for detection and therefore have the same limitation that is listed earlier in this bulletin related to programs that MBSA 1.2.1 does not detect.

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

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

Client Service for NetWare Memory Corruption Vulnerability - CVE-2006-4688:

There is a remote code execution vulnerability in Client Service for NetWare (CSNW) that could allow an attacker who successfully exploited this vulnerability to take complete control of the affected system.

Mitigating Factors for Client Service for NetWare Memory Corruption Vulnerability - CVE-2006-4688:


Windows XP Home Edition is not vulnerable to this issue. Windows XP Home Edition does not contain the vulnerable component.


On Windows Server 2003 and Windows Server 2003 Service Pack 1 an attacker would need to be an authenticated user with valid logon credentials in order to successfully carry out an attack on an affected system.


For customers who require the affected component firewall best practices and standard default firewall configurations can help protect networks from attacks that originate outside the enterprise perimeter. Best practices recommend that systems that are connected to the Internet have a minimal number of ports exposed.


By default, the Client Service for NetWare is not installed on any affected operating system version. Only customers who install this service are likely to be vulnerable to this issue.
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Workarounds for Client Service for NetWare Memory Corruption Vulnerability - CVE-2006-4688:

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 CSNW is commonly associated with the Internetwork Packet Exchange (IPX) and Sequenced Packet Exchange (SPX) protocols. However, CSNW could be exploited by using any installed protocol. Because TCP/IP is the most commonly used protocol, the following workarounds are based on TCP/IP. If protocols such as IPX and SPX are being used, you should also block the appropriate ports for those protocols. For more information about IPX and SPX, visit this site.


Remove the Client Service for NetWare if you do not need it.

If you no longer need the Client Service for NetWare, remove it. To do this, follow these steps.

Windows XP

1.


Open Network Connections.

2.


Right-click a local area connection and then click Properties.

3.


In the This connection uses the following items list click Client Service for NetWare.

4.


Click the General tab and then click Uninstall.

5.


Complete the removal by following the instructions on the screen.

Windows 2000

1.


Log in as administrator.

2.


Right-click on My Network Places.

3.


Click Properties.

4.


Click Local Area Connection.

5.


Highlight CSNW and click Uninstall.

6.


On the pop up dialog box that displays, click Yes.

Impact of Workaround: Some organizations require the affected component for important functions. Administrators should not remove the affected component unless they fully understand the effect that doing this will have on their environment.


Block TCP ports 139 and 445 at the firewall:

These ports are used to initiate a connection with the affected component. Blocking TCP ports 139 and 445 at the firewall will help protect systems that are behind that firewall from attempts to exploit this vulnerability. We recommend that you block all unsolicited inbound communication from the Internet to help prevent attacks that may use other ports. For more information about ports, visit the following Web site.

Impact of Workaround: Several Windows services use the affected ports. Blocking connectivity to the ports may cause various applications or services to not function. Some of the applications or services that could be impacted are listed below.

Applications that uses SMB (CIFS)

Applications that uses mailslots or named pipes (RPC over SMB)

Server (File and Print Sharing)

Group Policy

Net Logon

Distributed File System (DFS)

Terminal Server Licensing

Print Spooler

Computer Browser

Remote Procedure Call Locator

Fax Service

Indexing Service

Performance Logs and Alerts

Systems Management Server

License Logging Service


To help protect from network-based attempts to exploit this vulnerability, use a personal firewall, such as the Windows Firewall, which is included with Windows XP.

By default, the Windows Firewall feature in Windows XP and in Windows Server 2003 helps protect your Internet connection by blocking unsolicited incoming traffic. We recommend that you block all unsolicited incoming communication from the Internet.

To enable the Windows Firewall feature by using the Network Setup Wizard, follow these steps:

1.Click Start, and then click Control Panel.

2.Double-click Network Connections and then click Change Windows Firewall settings.

3.On the General tab, ensure that the On (recommended) value is selected. This will enable the Windows Firewall.

4.Once the Windows Firewall is enabled, select Don’t allow exceptions to prohibit all incoming traffic.

Note If you want to enable certain programs and services to communicate through the firewall, de-select Don’t allow exceptions and click the Exceptions tab. On the Exception tab, select the programs, protocols, and services you want to enable.


To help protect from network-based attempts to exploit this vulnerability, enable advanced TCP/IP filtering on systems that support this feature.

You can enable advanced TCP/IP filtering to block all unsolicited inbound traffic. For more information about how to configure TCP/IP filtering, see Microsoft Knowledge Base Article 309798.


To help protect from network-based attempts to exploit this vulnerability, block the affected ports by using IPSec on the affected systems.

Use Internet Protocol security (IPSec) to help protect network communications. Detailed information about IPSec and about how to apply filters is available in Microsoft Knowledge Base Article 313190 and Microsoft Knowledge Base Article 813878.
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FAQ for Client Service for NetWare Memory Corruption Vulnerability - CVE-2006-4688:

What is the scope of the vulnerability?
This is a remote code execution vulnerability in the Client Service for NetWare (CSNW). An attacker who successfully exploited this vulnerability could remotely 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. This service is also called Gateway Service for NetWare on Windows 2000 Server.

What causes the vulnerability?
An unchecked buffer in the Client Service for NetWare.

What is Client Service for NetWare?
The Client Service for NetWare (CSNW) allows the client to access NetWare file, print, and directory services. Both Microsoft and Novell provide a client service for this purpose: Microsoft Client Service for NetWare and Novell Client for Microsoft Windows XP, respectively. This vulnerability affects the Microsoft Client Service for NetWare. For more information about NetWare access, visit the following Web site. This service is also called Gateway Service for NetWare on Windows 2000 Server.

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?
Any anonymous user who could deliver a specially crafted message to the affected system could try to exploit this vulnerability.

How could an attacker exploit the vulnerability?
An attacker could try to exploit the vulnerability directly over a network by creating a series of specially crafted network messages and sending them to an affected system. The messages could then cause the affected system to execute code.

What systems are primarily at risk from the vulnerability?
All systems that have the Client Service for NetWare installed (also known as the Gateway Service for NetWare), are primarily at risk from this vulnerability. By default, this component is not installed on any affected operating system version. Only customers who manually install this component are likely to be vulnerable to this issue.

Could the vulnerability be exploited over the Internet?
Yes. An attacker could try to exploit this vulnerability over the Internet. Firewall best practices and standard default firewall configurations can help protect against attacks that originate from the Internet. Microsoft has provided information about how you can help protect your PC. End users can visit the Protect Your PC Web site. IT professionals can visit the Security Guidance Center Web site.

What does the update do?
The update removes the vulnerability by modifying the way that the affected component 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.

How does this vulnerability relate to the vulnerability that is corrected by MS05-046?
Both vulnerabilities were in the NetWare Client service. However, this update addresses a new vulnerability that was not addressed as part of MS05-046. MS05-046 helps protect against the vulnerability that is discussed in that bulletin, but does not address this new vulnerability. This update replaces MS005-046 on Windows XP Service Pack 2 only. You must install this update and MS05-046 to help protect your system against both vulnerabilities for the other affected platforms.
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NetWare Driver Denial of Service Vulnerability - CVE-2006-4689:

A denial of service vulnerability exists in Client Service for NetWare (CSNW) that could allow an attacker to send a specially crafted network message to an affected system running the Client Service for NetWare service. An attacker could cause the system to stop responding.

Mitigating Factors for NetWare Driver Denial of Service Vulnerability - CVE-2006-4689:


Windows XP Home Edition Service Pack 2 and Windows XP Media Center Edition 2005 do not contain the vulnerable component and are not vulnerable to this issue.


On Windows Server 2003 and Windows Server 2003 Service Pack 1 an attacker would need to be an authenticated user with valid logon credentials in order to successfully carry out an attack on an affected system.


For customers who require the affected component. firewall best practices and standard default firewall configurations can help protect networks from attacks that originate outside the enterprise perimeter. Best practices recommend that systems that are connected to the Internet have a minimal number of ports exposed.


By default, the Client Service for NetWare is not installed on any affected operating system version. Only customers who manually install this service are likely to be vulnerable to this issue.
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Workarounds for NetWare Driver Denial of Service Vulnerability - CVE-2006-4689:

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 CSNW is commonly associated with the Internetwork Packet Exchange (IPX) and Sequenced Packet Exchange (SPX) protocols. However, CSNW could be exploited by using any installed protocol. Because TCP/IP is the most commonly used protocol, the following workarounds are based on TCP/IP. If protocols such as IPX and SPX are being used, you should also block the appropriate ports for those protocols. For more information about IPX and SPX, visit the following Microsoft Web site.


Remove the Client Service for NetWare if you do not need it.

If you no longer need the Client Service for NetWare, remove it. To do this, follow these steps.

Windows XP

1.


Open Network Connections

2.


Right-click a local area connection and then click Properties.

3.


In the This connection uses the following items list. click Client Service for NetWare.

4.


Click the General tab and then click Uninstall.

5.


Complete the removal by following the instructions on the screen.

Windows 2000

1.


Log in as administrator

2.


Right-click on My Network Places

3.


Click Properties

4.


Click Local Area Connection

5.


Highlight CSNW and click Uninstall

6.


On the pop up dialog box that displays, click Yes

Impact of Workaround: Some organizations require the affected component for important functions. Administrators should not remove the affected component unless they fully understand the effect that doing this will have on their environment.


Block TCP ports 139 and 445 at the firewall:

These ports are used to initiate a connection with the affected component. Blocking TCP ports 139 and 445 at the firewall will help protect systems that are behind that firewall from attempts to exploit this vulnerability. We recommend that you block all unsolicited inbound communication from the Internet to help prevent attacks that may use other ports. For more information about ports, visit the following Web site.

Impact of Workaround: Several Windows services use the affected ports. Blocking connectivity to the ports may cause various applications or services to not function. Some of the applications or services that could be impacted are listed below.

Applications that uses SMB (CIFS)

Applications that uses mailslots or named pipes (RPC over SMB)

Server (File and Print Sharing)

Group Policy

Net Logon

Distributed File System (DFS)

Terminal Server Licensing

Print Spooler

Computer Browser

Remote Procedure Call Locator

Fax Service

Indexing Service

Performance Logs and Alerts

Systems Management Server

License Logging Service


To help protect from network-based attempts to exploit this vulnerability, use a personal firewall, such as the Windows Firewall, which is included with Windows XP.

By default, the Windows Firewall feature in Windows XP and in Windows Server 2003 helps protect your Internet connection by blocking unsolicited incoming traffic. We recommend that you block all unsolicited incoming communication from the Internet.

To enable the Windows Firewall feature by using the Network Setup Wizard, follow these steps:

1.Click Start, and then click Control Panel.

2.Double-click Network Connections and then click Change Windows Firewall settings.

3.On the General tab, ensure that the On (recommended) value is selected. This will enable the Windows Firewall.

4.Once the Windows Firewall is enabled, select Don’t allow exceptions to prohibit all incoming traffic.

Note – if you want to enable certain programs and services to communicate through the firewall, de-select Don’t allow exceptions and click the Exceptions tab. On the Exception tab, select the programs, protocols, and services you want to enable.

.


To help protect from network-based attempts to exploit this vulnerability, enable advanced TCP/IP filtering on systems that support this feature.

You can enable advanced TCP/IP filtering to block all unsolicited inbound traffic. For more information about how to configure TCP/IP filtering, see Microsoft Knowledge Base Article 309798.


To help protect from network-based attempts to exploit this vulnerability, block the affected ports by using IPSec on the affected systems.

Use Internet Protocol security (IPSec) to help protect network communications. Detailed information about IPSec and about how to apply filters is available in Microsoft Knowledge Base Article 313190 and Microsoft Knowledge Base Article 813878.
Top of sectionTop of section

FAQ for NetWare Driver Denial of Service Vulnerability - CVE-2006-4689:

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 and automatically restart. During that time, the server 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 accepting requests.

What causes the vulnerability?
An unchecked buffer in the Client Service for NetWare.

What is Client Service for NetWare?
The Client Service for NetWare (CSNW) allows the client to access NetWare file, print, and directory services. Both Microsoft and Novell provide a client service for this purpose: Microsoft Client Service for NetWare and Novell Client for Microsoft Windows XP, respectively. This vulnerability affects the Microsoft Client Service for NetWare. For more information about NetWare access, visit the following Web site. This service is also called Gateway Service for NetWare on Windows 2000 Server.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could cause the affected system to stop responding.

Who could exploit the vulnerability?
On Windows 2000 and Windows Service Pack 2, any anonymous user who could deliver a specially crafted message to the affected system could try to exploit this vulnerability. On Windows Server 2003 an attacker would need valid logon credentials in order to successfully exploit the vulnerability.

How could an attacker exploit the vulnerability?
An attacker could try to exploit the vulnerability directly over a network by creating a series of specially crafted network messages and sending them to an affected system. The messages could then cause the affected system to stop responding.

What systems are primarily at risk from the vulnerability?
All systems that have the Client Service for NetWare installed (also known as the Gateway Service for NetWare), are primarily at risk from this vulnerability. By default, this component is not installed on any affected operating system version. Only customers who manually install this component are likely to be vulnerable to this issue.

Could the vulnerability be exploited over the Internet?
Yes. An attacker could try to exploit this vulnerability over the Internet. Firewall best practices and standard default firewall configurations can help protect against attacks that originate from the Internet. Microsoft has provided information about how you can help protect your PC. End users can visit the Protect Your PC Web site. IT professionals can visit the Security Guidance Center Web site.

What does the update do?
The update removes the vulnerability by modifying the way that the affected component 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.

How does this vulnerability relate to the vulnerability that is corrected by MS05-046?
Both vulnerabilities were in the NetWare Client service. However, this update addresses a new vulnerability that was not addressed as part of MS05-046. MS05-046 helps protect against the vulnerability that is discussed in that bulletin, but does not address this new vulnerability. This update replaces MS005-046 on Windows XP Service Pack 2 only. You must install this update and MS05-046 to help protect your system against both vulnerabilities for the other affected platforms.

Acknowledgments

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


Peter Winter-Smith of NGS Software for reporting the Client Service for NetWare Memory Corruption Vulnerability - CVE-2006-4688.


Sam Arun Raj of McAfee for reporting the Client Service for NetWare Memory Corruption Vulnerability (CVE-2006-4688) and the Client Service for the NetWare Driver DoS Vulnerability (CVE-2006-4689).

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 (November 14, 2006): Bulletin published.

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