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Microsoft Security Bulletin MS09-048 - Critical

Vulnerabilities in Windows TCP/IP Could Allow Remote Code Execution (967723)

Published: September 08, 2009 | Updated: September 10, 2009

Version: 2.1

General Information

Executive Summary

This security update resolves several privately reported vulnerabilities in Transmission Control Protocol/Internet Protocol (TCP/IP) processing. The vulnerabilities could allow remote code execution if an attacker sent specially crafted TCP/IP packets over the network to a computer with a listening service. 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 security update is rated Critical for all supported editions of Windows Vista and Windows Server 2008, Important for all supported editions of Microsoft Windows 2000 and Windows Server 2003, and Low for all supported editions of Windows XP. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerabilities by dropping existing TCP connections adaptively and limiting the number of new TCP connections until system resources are restored, and changing the manner in which TCP/IP packets are processed. 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. Microsoft Knowledge Base Article 967723 documents the currently known issues that customers may experience when installing this security update. The article also documents recommended solutions for these issues.

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 SystemMaximum Security ImpactAggregate Severity RatingBulletins Replaced by this Update
Microsoft Windows 2000 Service Pack 4*Denial of ServiceImportantNone
Windows XP Service Pack 2 and Windows XP Service Pack 3*Denial of ServiceLowNone
Windows XP Professional x64 Edition Service Pack 2*Denial of ServiceLowNone
Windows Server 2003 Service Pack 2Denial of ServiceImportantNone
Windows Server 2003 x64 Edition Service Pack 2Denial of ServiceImportantNone
Windows Server 2003 with SP2 for Itanium-based SystemsDenial of ServiceImportantNone
Windows Vista, Windows Vista Service Pack 1, and Windows Vista Service Pack 2Remote Code ExecutionCriticalNone
Windows Vista x64 Edition, Windows Vista x64 Edition Service Pack 1, and Windows Vista x64 Edition Service Pack 2Remote Code ExecutionCriticalNone
Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2**Remote Code ExecutionCriticalNone
Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2**Remote Code ExecutionCriticalNone
Windows Server 2008 for Itanium-based Systems and Windows Server 2008 for Itanium-based Systems Service Pack 2Remote Code ExecutionCriticalNone

*No update available. For more information, see the Frequently Asked Questions (FAQ) Related to This Security Update entries.

**Windows Server 2008 Server Core installation affected. For supported editions of Windows Server 2008, this update applies, with the same severity rating, whether or not Windows Server 2008 was installed using the Server Core installation option. For more information on this installation option, see Server Core. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008; see Compare Server Core Installation Options.

Non-Affected Software

Operating System
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

If Microsoft Windows 2000 Service Pack 4 is listed as an affected product, why is Microsoft not issuing an update for it?
The architecture to properly support TCP/IP protection does not exist on Microsoft Windows 2000 systems, making it infeasible to build the fix for Microsoft Windows 2000 Service Pack 4 to eliminate the vulnerability. To do so would require rearchitecting a very significant amount of the Microsoft Windows 2000 Service Pack 4 operating system, not just the affected component. The product of such a rearchitecture effort would be sufficiently incompatible with Microsoft Windows 2000 Service Pack 4 that there would be no assurance that applications designed to run on Microsoft Windows 2000 Service Pack 4 would continue to operate on the updated system. The impact of a denial of service attack is that a system would become unresponsive due to memory consumption. However, a successful attack requires a sustained flood of specially crafted TCP packets, and the system will recover once the flood ceases. Microsoft recommends that customers running Microsoft Windows 2000 Service Pack 4 use a firewall to block access to the affected ports and limit the attack surface from untrusted networks.

If Windows XP is listed as an affected product, why is Microsoft not issuing an update for it?
By default, Windows XP Service Pack 2, Windows XP Service Pack 3, and Windows XP Professional x64 Edition Service Pack 2 do not have a listening service configured in the client firewall and are therefore not affected by this vulnerability. Windows XP Service Pack 2 and later operating systems include a stateful host firewall that provides protection for computers against incoming traffic from the Internet or from neighboring network devices on a private network. The impact of a denial of service attack is that a system would become unresponsive due to memory consumption. However, a successful attack requires a sustained flood of specially crafted TCP packets, and the system will recover once the flood ceases. This makes the severity rating Low for Windows XP. Windows XP is not affected by CVE-2009-1925. Customers running Windows XP are at reduced risk, and Microsoft recommends they use the firewall included with the operating system, or a network firewall, to block access to the affected ports and limit the attack surface from untrusted networks.

Does this update completely remove the vulnerabilities, TCP/IP Zero Window Size Vulnerability - CVE-2008-4609 and TCP/IP Orphaned Connections Vulnerability - CVE-2009-1926? 
Since the denial of service vulnerabilities, CVE-2008-4609 and CVE-2009-1926, affect the TCP/IP protocol itself, the updates for Windows Server 2003 and Windows Server 2008 do not completely remove the vulnerabilities; the updates merely provide more resilience to sustain operations during a flooding attack. Also, these denial of service vulnerabilities can be further mitigated through the use of NAT and reverse proxy servers, further lowering the severity of this issue on client workstations.

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.

Vulnerability Information

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 September bulletin summary. For more information, see Microsoft Exploitability Index.

Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected SoftwareTCP/IP Zero Window Size Vulnerability - CVE-2008-4609TCP/IP Timestamps Code Execution Vulnerability - CVE-2009-1925TCP/IP Orphaned Connections Vulnerability - CVE-2009-1926Aggregate Severity Rating
Microsoft Windows 2000 Service Pack 4*Important 
Denial of Service
Not applicableImportant 
Denial of Service
Important
Windows XP Service Pack 2 and Windows XP Service Pack 3*Low 
Denial of Service
Not applicableLow 
Denial of Service
Low
Windows XP Professional x64 Edition Service Pack 2*Low 
Denial of Service
Not applicableLow 
Denial of Service
Low
Windows Server 2003 Service Pack 2Important 
Denial of Service
Not applicableImportant 
Denial of Service
Important
Windows Server 2003 x64 Edition Service Pack 2Important 
Denial of Service
Not applicableImportant 
Denial of Service
Important
Windows Server 2003 with SP2 for Itanium-based SystemsImportant 
Denial of Service
Not applicableImportant 
Denial of Service
Important
Windows Vista, Windows Vista Service Pack 1, and Windows Vista Service Pack 2Moderate 
Denial of Service
Critical 
Remote Code Execution
Moderate 
Denial of Service
Critical
Windows Vista x64 Edition, Windows Vista x64 Edition Service Pack 1, and Windows Vista x64 Edition Service Pack 2Moderate 
Denial of Service
Critical 
Remote Code Execution
Moderate 
Denial of Service
Critical
Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2*Important 
Denial of Service
Critical 
Remote Code Execution
Important 
Denial of Service
Critical
Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2*Important 
Denial of Service
Critical 
Remote Code Execution
Important 
Denial of Service
Critical
Windows Server 2008 for Itanium-based Systems and Windows Server 2008 for Itanium-based Systems Service Pack 2Important 
Denial of Service
Critical 
Remote Code Execution
Important 
Denial of Service
Critical

*No update available. For more information, see the Frequently Asked Questions (FAQ) Related to This Security Update entries.

**Windows Server 2008 Server Core installation affected. For supported editions of Windows Server 2008, this update applies, with the same severity rating, whether or not Windows Server 2008 was installed using the Server Core installation option. For more information on this installation option, see Server Core. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008; see Compare Server Core Installation Options.

A denial of service vulnerability exists in TCP/IP processing in Microsoft Windows due to the way that Windows handles an excessive number of established TCP connections. The effect of this vulnerability can be amplified by the requirement to process specially crafted packets with a TCP receive window size set to a very small value or zero. An attacker could exploit the vulnerability by flooding a system with specially crafted packets causing the affected system to stop responding to new requests or automatically restart.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-4609.

Mitigating Factors for TCP/IP Zero Window Size Vulnerability - CVE-2008-4609

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:

  • 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.
  • In Windows Vista, if the network profile is set to "Public", the system is not affected by this vulnerability, since unsolicited inbound network packets are blocked by default.

Workarounds for TCP/IP Zero Window Size Vulnerability - CVE-2008-4609

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:

  • 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, use a personal firewall, such as the Internet Connection Firewall

    All supported editions of Windows Vista come with Windows Firewall, a two-way firewall that is automatically enabled.

    For all supported editions of Windows Server 2003, use the Internet Connection Firewall feature to help protect your Internet connection by blocking unsolicited incoming traffic. Microsoft recommends that you block all unsolicited incoming communication from the Internet.

    To enable the Windows Firewall feature by using the Network Setup Wizard, perform the following 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. When the Windows Firewall is enabled, select Don’t allow exceptions to prohibit all incoming traffic.

    For Windows Server 2003 systems, configure Internet Connection Firewall manually for a connection using the following steps:

    1. Click Start, and then click Control Panel.
    2. In the default Category View, click Networking and Internet Connections, and then click Network Connections.
    3. Right-click the connection on which you want to enable Internet Connection Firewall, and then click Properties.
    4. Click the Advanced tab.
    5. Click to select the Protect my computer or network by limiting or preventing access to this computer from the Internet check box, and then click OK.

    Note If you want to enable certain programs and services to communicate through the firewall, click Settings on the Advanced tab, and then select the programs, the protocols, and the services that are required.

FAQ for TCP/IP Zero Window Size Vulnerability - CVE-2008-4609

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. 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? 
The vulnerability is present because the Windows TCP/IP stack does not properly handle large numbers of established TCP connections. If these established connections are abused by a remote system requesting data and setting the TCP receive window size to a small or a zero value, the denial-of-service condition can be amplified. The TCP connections can also be kept alive by the attacker by sending ACK packets to the server. An excessive number of these malicious connections could consume server resources and prevent the server from responding to legitimate connections.

What is TCP/IP? 
TCP/IP is a set of networking protocols that are widely used on the Internet. TCP/IP provides communications across interconnected networks of computers that have diverse hardware architectures and that run various operating systems. TCP/IP includes standards for how computers communicate and conventions for connecting networks and for routing traffic. For more information about TCP/IP, see the TechNet article, Overview of networking and TCP/IP.

What is the TCP Receive Window Size? 
The Transmission Control Protocol (TCP) receive window size is the maximum amount of received data, in bytes, that can be buffered at one time on the receiving side of a connection. The sending host can send only that amount of data before waiting for an acknowledgment and window update from the receiving host. A TCP receive windows size set to zero keeps the connection alive, but prevents the transmission for passing any additional bytes of data until the window size is increased. For more information about TCP receive windows size option, see the MSDN article, TCP Receive Window Size and Window Scaling.

What might an attacker use the vulnerability to do? 
An attacker who successfully exploited this vulnerability could cause an affected system to become non-responsive.

How could an attacker exploit the vulnerability? 
An attacker could exploit the vulnerability by flooding a system with an excessive number of TCP connections and keeping them alive indefinitely, or by sending specially crafted packets with the TCP receive window size set to a very small value or zero.

What systems are primarily at risk from the vulnerability? 
All affected operating systems are at risk from this vulnerability. However, servers are at primary risk from this vulnerability because they are more likely to have a service listening on the network. Protocols or programs that maintain long sessions and have predictable TCP/IP information are at an increased risk of exploitation from this vulnerability.

What does the update do? 
The update addresses this vulnerability by dropping existing TCP connections adaptively and limiting the number of new TCP connections until system resources are restored.

When this security bulletin was issued, had this vulnerability been publicly disclosed? 
While the initial report was provided through responsible disclosure, the vulnerability was later disclosed publicly by a separate party. This security bulletin addresses the publicly disclosed vulnerability as well as additional issues discovered through internal investigations.

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.

A remote code execution vulnerability exists in the Windows TCP/IP stack due to the TCP/IP stack not cleaning up state information correctly. This causes the TCP/IP stack to reference a field as a function pointer when it actually contains other information. An anonymous attacker could exploit the vulnerability by sending specially crafted TCP/IP packets to a computer that has a service listening over the network. 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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2009-1925.

Mitigating Factors for TCP/IP Timestamps Code Execution Vulnerability - CVE-2009-1925

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:

  • 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.
  • In Windows Vista, if the network profile is set to "Public", the system is not affected by this vulnerability since unsolicited inbound network packets are blocked by default.
  • Windows Server 2003 is not affected by this vulnerability.

Workarounds for TCP/IP Timestamps Code Execution Vulnerability - CVE-2009-1925

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:

  • 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, use a personal firewall, such as the Internet Connection Firewall

    All supported editions of Windows Vista come with Windows Firewall, a two-way firewall that is automatically enabled.

    To enable the Windows Firewall feature by using the Network Setup Wizard, perform the following 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. When 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, click Settings on the Advanced tab, and then select the programs, the protocols, and the services that are required.

FAQ for TCP/IP Timestamps Code Execution Vulnerability - CVE-2009-1925

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 vulnerability is caused by the Windows TCP/IP stack not cleaning up state information correctly. This causes the TCP/IP stack to reference a field as a function pointer when it actually contains other information.

What is TCP/IP? 
TCP/IP is a set of networking protocols that are widely used on the Internet. TCP/IP provides communications across interconnected networks of computers that have diverse hardware architectures and that run various operating systems. TCP/IP includes standards for how computers communicate and conventions for connecting networks and for routing traffic. For more information about TCP/IP, see the TechNet article, Overview of networking and TCP/IP.

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 could try to exploit the vulnerability by creating specially crafted network packets and sending the packets to a listening service on an affected system.

What systems are primarily at risk from the vulnerability? 
All affected operating systems are at risk from this vulnerability. However, servers are at primary risk from this vulnerability because they are more likely to have a service listening on the network. Protocols or programs that maintain long sessions and have predictable TCP/IP information are at an increased risk to this issue.

What does the update do? 
The update addresses this vulnerability by changing the manner in which TCP/IP packets are processed.

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.

A denial of service vulnerability exists in TCP/IP processing in Microsoft Windows due to an error in the processing of specially crafted packets with a small or zero TCP receive window size. If an application closes a TCP connection with pending data to be sent and an attacker has set a small or zero TCP receive window size, the affected server will not be able to completely close the TCP connection. An attacker could exploit the vulnerability by flooding a system with specially crafted packets causing the affected system to stop responding to new requests. The system would remain non-responsive even after the attacker stops sending malicious packets.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2009-1926.

Mitigating Factors for TCP/IP Orphaned Connections Vulnerability - CVE-2009-1926

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:

  • 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.
  • In Windows Vista, if the network profile is set to "Public", the system is not affected by this vulnerability since unsolicited inbound network packets are blocked by default.

Workarounds for TCP/IP Orphaned Connections Vulnerability - CVE-2009-1926

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:

  • 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, use a personal firewall, such as the Internet Connection Firewall

    All supported editions of Windows Vista come with Windows Firewall, a two-way firewall that is automatically enabled.

    For all supported editions of Windows Server 2003, use the Internet Connection Firewall feature to help protect your Internet connection by blocking unsolicited incoming traffic. Microsoft recommends that you block all unsolicited incoming communication from the Internet.

    To enable the Windows Firewall feature by using the Network Setup Wizard, perform the following 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. When the Windows Firewall is enabled, select Don’t allow exceptions to prohibit all incoming traffic.

    For Windows Server 2003 systems, configure Internet Connection Firewall manually for a connection using the following steps:

    1. Click Start, and then click Control Panel.
    2. In the default Category View, click Networking and Internet Connections, and then click Network Connections.
    3. Right-click the connection on which you want to enable Internet Connection Firewall, and then click Properties.
    4. Click the Advanced tab.
    5. Click to select the Protect my computer or network by limiting or preventing access to this computer from the Internet check box, and then click OK.

    Note If you want to enable certain programs and services to communicate through the firewall, click Settings on the Advanced tab, and then select the programs, the protocols, and the services that are required.

FAQ for TCP/IP Orphaned Connections Vulnerability - CVE-2009-1926

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. 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? 
The vulnerability is due to the Windows TCP/IP stack allowing connections to hang indefinitely in the FIN-WAIT-1 or FIN-WAIT-2 state under certain conditions.

What is TCP/IP? 
TCP/IP is a set of networking protocols that are widely used on the Internet. TCP/IP provides communications across interconnected networks of computers that have diverse hardware architectures and that run various operating systems. TCP/IP includes standards for how computers communicate and conventions for connecting networks and for routing traffic. For more information about TCP/IP, see the TechNet article, Overview of networking and TCP/IP.

What are FIN-WAIT-1 and FIN-WAIT-2 states? 
A TCP connection goes through a series of different states during a transaction between client and server. The FIN-WAIT-1 state represents a system waiting for a connection termination request from the remote TCP, or an acknowledgment of the connection termination request previously sent. The FIN-WAIT-2 state represents a system waiting for a connection termination request from the remote TCP. For more information, see RFC 793.

What is the TCP Receive Window Size? 
The Transmission Control Protocol (TCP) receive window size is the maximum amount of received data, in bytes, that can be buffered at one time on the receiving side of a connection. The sending host can send only that amount of data before waiting for an acknowledgment and window update from the receiving host. A TCP receive windows size set to zero keeps the connection alive, but prevents the transmission for passing any additional bytes of data until the window size is increased. For more information about TCP receive windows size option, see the MSDN article, TCP Receive Window Size and Window Scaling.

What might an attacker use the vulnerability to do? 
An attacker who successfully exploited this vulnerability could cause an affected system to become non-responsive.

How could an attacker exploit the vulnerability? 
An attacker could exploit the vulnerability by flooding a system with specially crafted connections designed to keep the TCP connection state in the FIN-WAIT-1 or FIN-WAIT-2 state indefinitely.

What systems are primarily at risk from the vulnerability? 
All affected operating systems are at risk from this vulnerability. However, servers are at primary risk from this vulnerability because they are more likely to have a service listening on the network. Protocols or programs that maintain long sessions and have predictable TCP/IP information are at an increased risk to this issue.

What does the update do? 
The update addresses this vulnerability by dropping existing TCP connections adaptively and limiting the number of new TCP connections until system resources are restored.

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.

Update Information

Manage the software and security updates you need to deploy to the servers, desktop, and mobile systems in your organization. For more information see the TechNet Update Management Center. The Microsoft TechNet Security Web site provides additional information about security in Microsoft products.

Security updates are available from Microsoft Update and Windows Update. Security updates are also available from the Microsoft Download Center. You can find them most easily by doing a keyword search for "security update."

Finally, security updates can be downloaded from the Microsoft Update Catalog. The Microsoft Update Catalog provides a searchable catalog of content made available through Windows Update and Microsoft Update, including security updates, drivers and service packs. By searching using the security bulletin number (such as, "MS07-036"), you can add all of the applicable updates to your basket (including different languages for an update), and download to the folder of your choosing. For more information about the Microsoft Update Catalog, see the Microsoft Update Catalog FAQ.

Note Microsoft discontinued support for Office Update and the Office Update Inventory Tool as of August 1, 2009. To continue getting the latest updates for Microsoft Office products, use Microsoft Update. For more information, see About Microsoft Office Update: Frequently Asked Questions.

Detection and Deployment Guidance

Microsoft provides detection and deployment guidance for security updates. This guidance contains recommendations and information that can help IT professionals understand how to use various tools for detection and deployment of security updates. For more information, see Microsoft Knowledge Base Article 961747.

Microsoft Baseline Security Analyzer

Microsoft Baseline Security Analyzer (MBSA) allows administrators to scan local and remote systems for missing security updates as well as common security misconfigurations. For more information about MBSA, visit Microsoft Baseline Security Analyzer.

The following table provides the MBSA detection summary for this security update.

Software MBSA 2.1
Windows Server 2003 Service Pack 2Yes
Windows Server 2003 x64 Edition Service Pack 2Yes
Windows Server 2003 with SP2 for Itanium-based SystemsYes
Windows Vista, Windows Vista Service Pack 1, and Windows Vista Service Pack 2Yes
Windows Vista x64 Edition, Windows Vista x64 Edition Service Pack 1, and Windows Vista x64 Edition Service Pack 2Yes
Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2Yes
Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2Yes
Windows Server 2008 for Itanium-based Systems and Windows Server 2008 for Itanium-based Systems Service Pack 2Yes

For more information about MBSA 2.1, see MBSA 2.1 Frequently Asked Questions.

Windows Server Update Services

By using Windows Server Update Services (WSUS), administrators can deploy the latest critical updates and security updates for Windows 2000 operating systems and later, Office XP and later, Exchange Server 2003, and SQL Server 2000. For more information about how to deploy this security update using Windows Server Update Services, visit the Windows Server Update Services Web site.

Systems Management Server

The following table provides the SMS detection and deployment summary for this security update.

SoftwareSMS 2.0SMS 2003 with SUITSMS 2003 with ITMUConfiguration Manager 2007
Windows Server 2003 Service Pack 2YesYesYesYes
Windows Server 2003 x64 Edition Service Pack 2NoNoYesYes
Windows Server 2003 with SP2 for Itanium-based SystemsNoNoYesYes
Windows Vista, Windows Vista Service Pack 1, and Windows Vista Service Pack 2NoNoSee Note for Windows Vista and Windows Server 2008 belowYes
Windows Vista x64 Edition, Windows Vista x64 Edition Service Pack 1, and Windows Vista x64 Edition Service Pack 2NoNoSee Note for Windows Vista and Windows Server 2008 belowYes
Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2NoNoSee Note for Windows Vista and Windows Server 2008 belowYes
Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2NoNoSee Note for Windows Vista and Windows Server 2008 belowYes
Windows Server 2008 for Itanium-based Systems and Windows Server 2008 for Itanium-based Systems Service Pack 2NoNoSee Note for Windows Vista and Windows Server 2008 belowYes

For SMS 2.0 and SMS 2003, the Security Update Inventory Tool (SUIT) can be used by SMS to detect security updates. See also Downloads for Systems Management Server 2.0.

For SMS 2003, the SMS 2003 Inventory Tool for Microsoft Updates (ITMU) 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 ITMU, see SMS 2003 Inventory Tool for Microsoft Updates. For more information about SMS scanning tools, see SMS 2003 Software Update Scanning Tools. See also Downloads for Systems Management Server 2003.

System Center Configuration Manager 2007 uses WSUS 3.0 for detection of updates. For more information about Configuration Manager 2007 Software Update Management, visit System Center Configuration Manager 2007.

Note for Windows Vista and Windows Server 2008 Microsoft Systems Management Server 2003 with Service Pack 3 includes support for Windows Vista and Windows Server 2008 manageability.

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

For more detailed information, see Microsoft Knowledge Base Article 910723: Summary list of monthly detection and deployment guidance articles.

Update Compatibility Evaluator and Application Compatibility Toolkit

Updates often write to the same files and registry settings required for your applications to run. This can trigger incompatibilities and increase the time it takes to deploy security updates. You can streamline testing and validating Windows updates against installed applications with the Update Compatibility Evaluator components included with Application Compatibility Toolkit.

The Application Compatibility Toolkit (ACT) contains the necessary tools and documentation to evaluate and mitigate application compatibility issues before deploying Microsoft Windows Vista, a Windows Update, a Microsoft Security Update, or a new version of Windows Internet Explorer in your environment.

Affected Software

For information about the specific security update for your affected software, click the appropriate link:

Windows Server 2003 (all editions)

Reference Table

The following table contains the security update information for this software. You can find additional information in the subsection, Deployment Information, in this section.

Inclusion in Future Service PacksThe update for this issue will be included in a future service pack or update rollup
Deployment
Installing without user interventionFor all supported 32-bit editions of Windows Server 2003:
Windowsserver2003-kb967723-x86-enu /quiet
For all supported x64-based editions of Windows Server 2003:
Windowsserver2003.WindowsXP-KB967723-x64-enu /quiet
For all supported Itanium-based editions of Windows Server 2003:
Windowsserver2003-KB967723-ia64-enu /quiet
Installing without restartingFor all supported 32-bit editions of Windows Server 2003:
Windowsserver2003-kb967723-x86-enu /norestart
For all supported x64-based editions of Windows Server 2003:
Windowsserver2003.WindowsXP-KB967723-x64-enu /norestart
For all supported Itanium-based editions of Windows Server 2003:
Windowsserver2003-KB967723-ia64-enu /norestart
Update log fileKB967723.log
Further informationSee the subsection, Detection and Deployment Tools and Guidance
Restart Requirement
Restart required?Yes, you must restart your system after you apply this security update.
HotPatchingThis security update does not support HotPatching. For more information about HotPatching, see Microsoft Knowledge Base Article 897341.
Removal InformationUse Add or Remove Programs tool in Control Panel or the Spuninst.exe utility located in the %Windir%\$NTUninstallKB967723$\Spuninst folder
File InformationSee Microsoft Knowledge Base Article 967723
Registry Key VerificationHKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows Server 2003\SP3\KB967723\Filelist

Deployment Information

Installing the Update

When you install this security update, the installer checks to see if one or more of the files that are being updated on your system have previously been updated by a Microsoft hotfix.

If you have previously installed a hotfix to update one of these files, the installer copies the RTMQFE, SP1QFE, or SP2QFE files to your system. Otherwise, the installer copies the RTMGDR, SP1GDR, or SP2GDR files to your system. Security updates may not contain all variations of these files. For more information about this behavior, see Microsoft Knowledge Base Article 824994.

For more information about the installer, visit the Microsoft TechNet Web site.

For more information about the terminology that appears in this bulletin, such as hotfix, see Microsoft Knowledge Base Article 824684.

This security update supports the following setup switches.

Supported Security Update Installation Switches
SwitchDescription
/helpDisplays the command-line options.
Setup Modes
/passiveUnattended Setup mode. No user interaction is required, but installation status is displayed. If a restart is required at the end of Setup, a dialog box will be presented to the user with a timer warning that the computer will restart in 30 seconds.
/quietQuiet mode. This is the same as unattended mode, but no status or error messages are displayed.
Restart Options
/norestartDoes not restart when installation has completed.
/forcerestartRestarts the computer after installation and force other applications to close at shutdown without saving open files first.
/warnrestart[:x]Presents a dialog box with a timer warning the user that the computer will restart in x seconds. (The default setting is 30 seconds.) Intended for use with the /quiet switch or the /passive switch.
/promptrestartDisplays a dialog box prompting the local user to allow a restart.
Special Options
/overwriteoemOverwrites OEM files without prompting.
/nobackupDoes not back up files needed for uninstall.
/forceappscloseForces other programs to close when the computer shuts down.
/log:pathAllows the redirection of installation log files.
/integrate:pathIntegrates the update into the Windows source files. These files are located at the path that is specified in the switch.
/extract[:path]Extracts files without starting the Setup program.
/EREnables extended error reporting.
/verboseEnables verbose logging. During installation, creates %Windir%\CabBuild.log. This log details the files that are copied. Using this switch may cause the installation to proceed more slowly.

Note You can combine these switches into one command. For backward compatibility, the security update also supports many of the setup switches that the earlier version of the Setup program uses. For more information about the supported installation switches, see Microsoft Knowledge Base Article 262841.

Removing the Update

This security update supports the following setup switches.

Supported Spuninst.exe Switches
SwitchDescription
/helpDisplays the command-line options.
Setup Modes
/passiveUnattended Setup mode. No user interaction is required, but installation status is displayed. If a restart is required at the end of Setup, a dialog box will be presented to the user with a timer warning that the computer will restart in 30 seconds.
/quietQuiet mode. This is the same as unattended mode, but no status or error messages are displayed.
Restart Options
/norestartDoes not restart when installation has completed.
/forcerestartRestarts the computer after installation and force other applications to close at shutdown without saving open files first.
/warnrestart[:x]Presents a dialog box with a timer warning the user that the computer will restart in x seconds. (The default setting is 30 seconds.) Intended for use with the /quiet switch or the /passive switch.
/promptrestartDisplays a dialog box prompting the local user to allow a restart.
Special Options
/forceappscloseForces other programs to close when the computer shuts down.
/log:pathAllows the redirection of installation log files.

Verifying that the Update Has Been Applied

  • Microsoft Baseline Security Analyzer

    To verify that a security update has been applied to an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. See the section, Detection and Deployment Tools and Guidance, earlier in this bulletin for more information.

  • File Version Verification

    Because there are several editions of Microsoft Windows, the following steps may be different on your system. If they are, see your product documentation to complete these steps.

    1. Click Start, and then click Search.
    2. In the Search Results pane, click All files and folders under Search Companion.
    3. In the All or part of the file name box, type a file name from the appropriate file information table, and then click Search.
    4. In the list of files, right-click a file name from the appropriate file information table, and then click Properties.

      Note Depending on the edition of the operating system, or the programs that are installed on your system, some of the files that are listed in the file information table may not be installed.
    5. On the Version tab, determine the version of the file that is installed on your system by comparing it to the version that is documented in the appropriate file information table.

      Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.
  • Registry Key Verification

    You may also be able to verify the files that this security update has installed by reviewing the registry keys listed in the Reference Table in this section.

    These registry keys may not contain a complete list of installed files. Also, these registry keys may not be created correctly when an administrator or an OEM integrates or slipstreams this security update into the Windows installation source files.

Windows Vista (all editions)

Reference Table

The following table contains the security update information for this software. You can find additional information in the subsection, Deployment Information, in this section.

Inclusion in Future Service PacksThe update for this issue will be included in a future service pack or update rollup
Deployment
Installing without user interventionFor all supported 32-bit editions of Windows Vista:
Windows6.0-KB967723-x86 /quiet

For all supported x64-based editions of Windows Vista:
Windows6.0-KB967723-x64 /quiet
Installing without restartingFor all supported 32-bit editions of Windows Vista:
Windows6.0-KB967723-x86 /quiet /norestart

For all supported x64-based editions of Windows Vista:
Windows6.0-KB967723-x64 /quiet /norestart
Further informationSee the subsection, Detection and Deployment Tools and Guidance
Restart Requirement
Restart required?Yes, you must restart your system after you apply this security update.
HotPatchingNot applicable.
Removal InformationWUSA.exe does not support uninstall of updates. To uninstall an update installed by WUSA, click Control Panel, and then click Security. Under Windows Update, click View installed updates and select from the list of updates.
File InformationSee Microsoft Knowledge Base Article 967723
Registry Key VerificationNote A registry key does not exist to validate the presence of this update.

Deployment Information

Installing the Update

When you install this security update, the installer checks whether one or more of the files that are being updated on your system have previously been updated by a Microsoft hotfix.

For more information about the terminology that appears in this bulletin, such as hotfix, see Microsoft Knowledge Base Article 824684.

This security update supports the following setup switches.

Supported Security Update Installation Switches
SwitchDescription
/?, /h, /helpDisplays help on supported switches.
/quietSuppresses the display of status or error messages.
/norestartWhen combined with /quiet, the system will not be restarted after installation even if a restart is required to complete installation.

Note For more information about the wusa.exe installer, see Microsoft Knowledge Base Article 934307.

Verifying That the Update Has Been Applied

  • Microsoft Baseline Security Analyzer

    To verify that a security update has been applied to an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. See the section, Detection and Deployment Tools and Guidance, earlier in this bulletin for more information.

  • File Version Verification

    Because there are several editions of Microsoft Windows, the following steps may be different on your system. If they are, see your product documentation to complete these steps.

    1. Click Start and then enter an update file name in Start Search.
    2. When the file appears under Programs, right-click on the file name and click Properties.
    3. Under the General tab, compare the file size with the file information tables provided in the bulletin KB article.
    4. You may also click on the Details tab and compare information, such as file version and date modified, with the file information tables provided in the bulletin KB article.
    5. Finally, you may also click on the Previous Versions tab and compare file information for the previous version of the file with the file information for the new, or updated, version of the file.

Windows Server 2008 (all editions)

Reference Table

The following table contains the security update information for this software. You can find additional information in the subsection, Deployment Information, in this section.

Inclusion in Future Service PacksThe update for this issue will be included in a future service pack or update rollup
Deployment
Installing without user interventionFor all supported 32-bit editions of Windows Server 2008:
Windows6.0-KB967723-x86 /quiet

For all supported x64-based editions of Windows Server 2008:
Windows6.0-KB967723-x64 /quiet

For all supported Itanium-based editions of Windows Server 2008:
Windows6.0-KB967723-ia64 /quiet
Installing without restartingFor all supported 32-bit editions of Windows Server 2008:
Windows6.0-KB967723-x86 /quiet /norestart

For all supported x64-based editions of Windows Server 2008:
Windows6.0-KB967723-x64 /quiet /norestart

For all supported Itanium-based editions of Windows Server 2008:
Windows6.0-KB967723-ia64 /quiet /norestart
Further informationSee the subsection, Detection and Deployment Tools and Guidance
Restart Requirement
Restart required?Yes, you must restart your system after you apply this security update.
HotPatchingNot applicable.
Removal InformationWUSA.exe does not support uninstall of updates. To uninstall an update installed by WUSA, click Control Panel, and then click Security. Under Windows Update, click View installed updates and select from the list of updates.
File InformationSee Microsoft Knowledge Base Article 967723
Registry Key VerificationNote A registry key does not exist to validate the presence of this update.

Deployment Information

Installing the Update

When you install this security update, the installer checks whether one or more of the files that are being updated on your system have previously been updated by a Microsoft hotfix.

For more information about the terminology that appears in this bulletin, such as hotfix, see Microsoft Knowledge Base Article 824684.

This security update supports the following setup switches.

Supported Security Update Installation Switches
SwitchDescription
/?, /h, /helpDisplays help on supported switches.
/quietSuppresses the display of status or error messages.
/norestartWhen combined with /quiet, the system will not be restarted after installation even if a restart is required to complete installation.

Note For more information about the wusa.exe installer, see Microsoft Knowledge Base Article 934307.

Verifying That the Update Has Been Applied

  • Microsoft Baseline Security Analyzer

    To verify that a security update has been applied to an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. See the section, Detection and Deployment Tools and Guidance, earlier in this bulletin for more information.

  • File Version Verification

    Because there are several editions of Microsoft Windows, the following steps may be different on your system. If they are, see your product documentation to complete these steps.

    1. Click Start and then enter an update file name in Start Search.
    2. When the file appears under Programs, right-click on the file name and click Properties.
    3. Under the General tab, compare the file size with the file information tables provided in the bulletin KB article.
    4. You may also click on the Details tab and compare information, such as file version and date modified, with the file information tables provided in the bulletin KB article.
    5. Finally, you may also click on the Previous Versions tab and compare file information for the previous version of the file with the file information for the new, or updated, version of the file.

Other Information

Acknowledgments

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

  • Jack C. Louis of Outpost24 for reporting the TCP/IP Zero Window Size Vulnerability (CVE-2008-4609)
  • Fabian Yamaguchi of Recurity Labs GmbH for reporting the TCP/IP Orphaned Connections Vulnerability (CVE-2009-1926)

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 (September 8, 2009): Bulletin published.
  • V2.0 (September 9, 2009): Added Windows XP Service Pack 2, Windows XP Service Pack 3, and Windows XP Professional x64 Edition Service Pack 2 to the Affected Software table. Also added entries to the section, Frequently Asked Questions (FAQ) Related to This Security Update, explaining why Microsoft is not releasing updates for the affected Windows XP editions, and clarifying the scope of the updates for the denial of service vulnerabilities. There were no changes to the security updates offered in this bulletin.
  • V2.1 (September 10, 2009): Updated the Microsoft Windows 2000 and Windows XP entries to the section, Frequently Asked Questions (FAQ) Related to This Security Update, to clarify the scope of the vulnerability and list recommended actions.

Built at 2014-04-16T02:39:51Z-07:00

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