Microsoft Security Bulletin MS09-039 - Critical Vulnerabilities in WINS Could Allow Remote Code Execution (969883)

Microsoft Security Bulletin MS09-039 - Critical
Vulnerabilities in WINS Could Allow Remote Code Execution (969883)
Published: August 11, 2009

Version: 1.0
General Information
Executive Summary

This security update resolves two privately reported vulnerabilities in the Windows Internet Name Service (WINS). Either vulnerability could allow remote code execution if a user received a specially crafted WINS replication packet on an affected system running the WINS service. By default, WINS is not installed on any affected operating system version. Only customers who manually install this component are affected by this issue.

This security update is rated Critical for all supported editions of Microsoft Windows 2000 Server Service Pack 4 and Windows Server 2003. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerabilities by correcting the manner in which the WINS service calculates buffer length and introducing proper data validations on received packets on the WINS server. For more information about the vulnerabilities, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.

Recommendation. The majority of customers have automatic updating enabled and will not need to take any action because this security update will be downloaded and installed automatically. Customers who have not enabled automatic updating need to check for updates and install this update manually. For information about specific configuration options in automatic updating, see Microsoft Knowledge Base Article 294871.

For administrators and enterprise installations, or end users who want to install this security update manually, Microsoft recommends that customers apply the update immediately using update management software, or by checking for updates using the Microsoft Update service.

See also the section, Detection and Deployment Tools and Guidance, later in this bulletin.

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 Maximum Security Impact Aggregate Severity Rating Bulletins Replaced by this Update

Microsoft Windows 2000 Server Service Pack 4

Remote Code Execution

Critical

MS09-008

Windows Server 2003 Service Pack 2

Remote Code Execution

Critical

MS09-008

Windows Server 2003 x64 Edition Service Pack 2

Remote Code Execution

Critical

MS09-008

Windows Server 2003 with SP2 for Itanium-based Systems

Remote Code Execution

Critical

MS09-008

Non-Affected Software
Operating System

Microsoft Windows 2000 Professional Service Pack 4

Windows XP Service Pack 2 and Service Pack 3

Windows XP Professional x64 Edition Service Pack 2

Windows Vista, Windows Vista Service Pack 1, and Windows Vista Service Pack 2

Windows Vista x64 Edition, Windows Vista x64 Edition Service Pack 1, and Windows Vista x64 Edition Service Pack 2

Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2*

Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2*

Windows Server 2008 for Itanium-based Systems and Windows Server 2008 for Itanium-based Systems Service Pack 2

Windows 7 for 32-bit Systems

Windows 7 for x64-based Systems

Windows Server 2008 R2 for x64-based Systems

Windows Server 2008 R2 for Itanium-based Systems
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Frequently Asked Questions (FAQ) Related to This Security Update

I am running one of the platforms that are listed in the Affected Software table. Why am I not being offered the update?
The update can only be installed if WINS is enabled on the operating systems listed in the Affected Software table. By default, WINS is not enabled on these operating systems, so the update will not be offered unless WINS has been enabled.

Where are the file information details?
Refer to the reference tables in the Security Update Deployment section for the location of the file information details.

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 need to install this update only.

I am using an older release 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 releases are affected. Other releases are past their support life cycle. To determine the support life cycle for your software release, visit Microsoft Support Lifecycle.

It should be a priority for customers who have older releases of the software to migrate to supported releases 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 releases 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

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the August bulletin summary. For more information, see Microsoft Exploitability Index.
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software WINS Heap Overflow Vulnerability - CVE-2009-1923 WINS Integer Overflow Vulnerability - CVE-2009-1924 Aggregate Severity Rating

Microsoft Windows 2000 Server Service Pack 4

Critical
Remote Code Execution

Critical
Remote Code Execution

Critical

Windows Server 2003 Service Pack 2

Critical
Remote Code Execution

Not Applicable

Critical

Windows Server 2003 x64 Edition Service Pack 2

Critical
Remote Code Execution

Not Applicable

Critical

Windows Server 2003 with SP2 for Itanium-based Systems

Critical
Remote Code Execution

Not Applicable

Critical
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WINS Heap Overflow Vulnerability - CVE-2009-1923

A remote code execution vulnerability exists in the Windows Internet Name Service (WINS) due to a buffer overflow caused by incorrect calculation of buffer length when processing specially crafted WINS network packets. 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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2009-1923.

Mitigating Factors for WINS Heap Overflow Vulnerability - CVE-2009-1923

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:
•

By default, WINS is not installed on any affected operating system version. Only customers who manually install this component are affected by this issue.
•

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.
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Workarounds for WINS Heap Overflow Vulnerability - CVE-2009-1923

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:
•

Block TCP port 42 and UDP port 42 at your firewall.

These ports are used to initiate a connection with a remote WINS server. Blocking these ports at the firewall will help prevent systems that are behind that firewall from being attacked by attempts to exploit this vulnerability. It is possible that other ports may be found that could be used to exploit this vulnerability. The ports that are listed are the most common attack vectors. We recommend blocking all inbound unsolicited communication from the Internet.
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FAQ for WINS Heap Overflow Vulnerability - CVE-2009-1923

What is the scope of the vulnerability?
This is a remote code execution 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.

What causes the vulnerability?
The vulnerability results from the manner in which WINS calculates a buffer length when processing specially crafted WINS network packets.

What is WINS?
WINS is a protocol that was designed specifically to support NetBIOS over TCP/IP (NetBT). WINS is required for any environment in which users access resources that have NetBIOS names. If you do not use WINS in such a network, you cannot connect to a remote network resource by using its NetBIOS name unless you use Lmhosts files, and you might be unable to establish file and print sharing connections. For more information, see the WINS TechNet article.

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

How could an attacker exploit the vulnerability?
An attacker could exploit this vulnerability by sending a specially crafted WINS replication packet to an affected system running the WINS service. A WINS system does not need to have replication enabled for this attack to succeed.

What systems are primarily at risk from the vulnerability?
Windows WINS Servers are at risk from this vulnerability.

What does the update do?
The update addresses the vulnerability by correcting the manner in which the WINS service calculates buffer length.

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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WINS Integer Overflow Vulnerability - CVE-2009-1924

A remote code execution vulnerability exists in the default configuration of the Windows Internet Name Service (WINS) due to insufficient validation of data structures within specially crafted WINS network packets received from a trusted WINS replication partner.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2009-1924.

Mitigating Factors for WINS Integer Overflow Vulnerability - CVE-2009-1924

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:
•

In the default configuration, this attack can only be successfully carried out from a trusted WINS replication partner. However, if the registry key "HKLM\System\CCS\Services\WINS\Parameteres\RplOnlyWCnfPnrs" is set to 0, anyone on the network on the network can exploit this vulnerability. See KB251067 for a full description of this registry key and its usage.
•

By default, WINS is not installed on any affected operating system version. Only customers who manually install this are affected by this issue.
•

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.
•

This issue only affects WINS running on Windows 2000 Server Service Pack 4.
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Workarounds for WINS Integer Overflow Vulnerability - CVE-2009-1924

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:
•

Block TCP port 42 and UDP port 42 at your firewall.

These ports are used to initiate a connection with a remote WINS server. Blocking these ports at the firewall will help prevent systems that are behind that firewall from being attacked by attempts to exploit this vulnerability. It is possible that other ports may be found that could be used to exploit this vulnerability. The ports that are listed are the most common attack vectors. We recommend blocking all inbound unsolicited communication from the Internet.
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FAQ for WINS Integer Overflow Vulnerability - CVE-2009-1924

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could run arbitrary code with elevated privileges on vulnerable systems. An attacker could then install programs or view, change, or delete data; or create new accounts with full user rights.

What causes the vulnerability?
The issue results from WINS improperly validating and restricting buffer lengths passed to the heap.

What is WINS?
WINS is a protocol that was designed specifically to support NetBIOS over TCP/IP (NetBT). WINS is required for any environment in which users access resources that have NetBIOS names. If you do not use WINS in such a network, you cannot connect to a remote network resource by using its NetBIOS name unless you use Lmhosts files, and you might be unable to establish file and print sharing connections. For more information, see the WINS TechNet article.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could run arbitrary code. 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 who is trusted for WINS replication could try to exploit the vulnerability by creating specially crafted packets and sending the packets to an affected WINS system.

What systems are primarily at risk from the vulnerability?
Windows WINS servers running on Windows 2000 server are at risk from the vulnerability.

What does the update do?
The update addresses the vulnerability by introducing proper data validations on received packets on the WINS server.

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
Acknowledgments

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

TippingPoint and the Zero Day Initiative for reporting the WINS Heap Overflow Vulnerability (CVE-2009-1923)
•

LiGen of National University of Defense Technology for reporting the WINS Integer Overflow Vulnerability (CVE-2009-1924)
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Microsoft Active Protections Program (MAPP)

To improve security protections for customers, Microsoft provides vulnerability information to major security software providers in advance of each monthly security update release. Security software providers can then use this vulnerability information to provide updated protections to customers via their security software or devices, such as antivirus, network-based intrusion detection systems, or host-based intrusion prevention systems. To determine whether active protections are available from security software providers, please visit the active protections Web sites provided by program partners, listed in Microsoft Active Protections Program (MAPP) Partners.

Support
•

Customers in the U.S. and Canada can receive technical support from Security Support or 1-866-PCSAFETY. There is no charge for support calls that are associated with security updates. For more information about available support options, see Microsoft Help and Support.
•

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.

Revisions
•

V1.0 (August 11, 2009): Bulletin published.