Security Bulletin

Microsoft Security Bulletin MS08-004 - Important

Vulnerability in Windows TCP/IP Could Allow Denial of Service (946456)

Published: February 12, 2008

Version: 1.0

General Information

Executive Summary

This important update resolves a privately reported vulnerability in Transmission Control Protocol/Internet Protocol (TCP/IP) processing. An attacker who successfully exploited this vulnerability could cause the affected system to stop responding and automatically restart.

This is an important security update for all supported editions of Windows Vista. For more information, see the subsection, Affected and Non-Affected Software, in this section.

This security update addresses the vulnerability by validating the IP address provided by a DHCP server or assigned by command or API at the local machine. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.

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

Known Issues. None

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

Non-Affected Software

Frequently Asked Questions (FAQ) Related to This Security Update

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

Severity Ratings and Vulnerability Identifiers

Windows Vista TCP/IP Vulnerability - CVE-2008-0084

A denial of service vulnerability exists in TCP/IP processing in Windows Vista. An attacker could exploit the vulnerability by creating a specially crafted DHCP server that returns a specially crafted packet to a host, corrupting TCP/IP structures and causing the affected system to stop responding and automatically restart.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-0084.

Mitigating Factors for Windows Vista TCP/IP Vulnerability - CVE-2008-0084

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of vulnerability. The following mitigating factors may be helpful in your situation:

• An attacker can only receive a DHCP request and respond with a specially crafted packet by using a specially crafted DHCP server within the same link or via a DHCP Relay Agent.

Workarounds for Windows Vista TCP/IP Vulnerability - CVE-2008-0084

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:

• Assign a static IP address to the client computer instead of allowing the client computer to automatically request an IP address. Perform the following steps:

  1. On the client computer, click Control Panel, then click Network and Sharing Center.
  2. Local Area Connection and click View Status.
  3. Click Properties.
  4. Click Internet Protocol Version 4 (TCP/IPv4) and click Properties.
  5. Select Use the following IP address and enter the values in IP address, Subnet mask, Default gateway, and Preferred DNS server.
  6. Click OK.

  Impact of workaround. Automatic requests for an IP address have been bypassed.

  How to undo the workaround. Re-enable automatic requests for an IP address by performing the following steps:

  1. On the client computer, click Control Panel, then click Network and Sharing Center or Network Connections.
  2. Local Area Connection and click View Status.
  3. Click Properties.
  4. Click Internet Protocol Version 4 (TCP/IPv4) click Properties.
  5. Select Obtain an IP address automatically.
  6. Click OK.

FAQ for Windows Vista TCP/IP Vulnerability - CVE-2008-0084

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. 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 lies in the way that the TCP/IP stack handles packets received from DHCP servers.

What is DHCP? 
Dynamic Host Configuration Protocol (DHCP) is a protocol used by networked devices (hosts) to obtain various parameters necessary for the hosts to operate in an Internet Protocol (IP) network. By using this protocol, system administration workload greatly decreases, and devices can be added to the network with minimal or no manual configurations. A DHCP server assigns IP addresses to host computers.

What is TCP/IP? Is TCP/IP vulnerable? 
TCP/IP is the suite of communications protocols used for transmitting data over networks. The current version of TCP/IP is TCP/IPv4, which is vulnerable (see also the Workarounds section of this vulnerability entry). The next version, TCP/IPv6, is not affected by this vulnerability.

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 and automatically restart.

How could an attacker exploit the vulnerability? 
An attacker could exploit the vulnerability by creating a specially crafted DHCP server that returns a specially crafted packet to a host, corrupting TCP/IP structures and causing the affected system to stop responding and automatically restart.

What systems are primarily at risk from the vulnerability? 
Windows Vista clients that request an IP address from the DHCP server are primarily at risk.

What does the update do? 
The update removes the vulnerability by adding more validation to the way that the TCP/IP stack handles packets received from DHCP servers.

When this security bulletin was issued, had this vulnerability been publicly disclosed? 
No. Microsoft received information about this vulnerability through responsible disclosure.

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

Detection and Deployment Tools and Guidance

Manage the software and security updates you need to deploy to the servers, desktop, and mobile computers 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, Windows Update, and Office 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.

Detection and Deployment Guidance

Microsoft has provided detection and deployment guidance for this month’s security updates. This guidance will also help IT professionals understand how they can use various tools to help deploy the security update, such as Windows Update, Microsoft Update, Office Update, the Microsoft Baseline Security Analyzer (MBSA), the Office Detection Tool, Microsoft Systems Management Server (SMS), and the Extended Security Update Inventory Tool. For more information, see Microsoft Knowledge Base Article 910723.

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.

Note for Windows Vista Microsoft does not support installing MBSA 2.0.1 on computers that run Windows Vista, but you may install MBSA 2.0.1 on a supported operating system and then scan the Windows Vista-based computer remotely. For additional information about MBSA support for Windows Vista, visit the MBSA Web site. See also Microsoft Knowledge Base Article 931943: Microsoft Baseline Security Analyzer (MBSA) support for Windows Vista.

For more information about MBSA 2.0.1, see MBSA 2.0 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 to Windows 2000 and later operating systems. 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.

For SMS 2.0, the SMS SUS Feature Pack, which includes 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. SMS 2003 can also use the Microsoft Office Inventory Tool to detect required updates for Microsoft Office applications. For more information about the Office Inventory Tool and other scanning tools, see SMS 2003 Software Update Scanning Tools. See also Downloads for Systems Management Server 2003.

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

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

Security Update Deployment

Affected Software

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

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.

File Information

The English version of this security update has the file attributes that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

For all supported 32-bit editions of Windows Vista:

For all supported x64-based editions of Windows Vista:

Note For a complete list of supported versions and editions, see the Support Lifecycle Index. For a complete list of service packs, see Lifecycle Supported Service Packs. For more information on the support lifecycle policy, see Microsoft Support Lifecycle.

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.

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 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.

Other Information

Acknowledgments

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

• Tomas Potok, Martin Dominik, Martin Luptak, Eva Juhasova of Whitestein Technologies for reporting the Windows Vista TCP/IP Vulnerability (CVE-2008-0084).

Support

• Customers in the U.S. and Canada can receive technical support from Microsoft Product Support Services at 1-866-PCSAFETY. There is no charge for support calls that are associated with security updates.
• 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 (February 12, 2008): Bulletin published.

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