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 Top of sectionTop of section 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
Denial of Service
Windows Vista x64 Edition
Denial of Service
Non-Affected Software Operating System
Microsoft Windows 2000 Service Pack 4
Windows XP Service Pack 2
Windows XP Professional x64 Edition and Windows XP Professional x64 Edition Service Pack 2
Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2
Windows Server 2003 x64 Edition and Windows 2003 Server x64 Edition Service Pack 2
Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium based Systems
Windows Vista Service Pack 1 (all editions)
Windows Server 2008 (all editions) Top of sectionTop of section
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. Top of sectionTop of section Vulnerability Information
Severity Ratings and Vulnerability Identifiers Vulnerability Severity Rating and Maximum Security Impact by Affected Software Affected Software Windows Vista TCP/IP Vulnerability - CVE-2008-0084 Aggregate Severity Rating
Important Denial of Service
WindowsVista x64 Edition
Important Denial of Service
Important Top of sectionTop of section
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. Top of sectionTop of section
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:
On the client computer, click Control Panel, then click Network and Sharing Center.
Local Area Connection and click ViewStatus.
Click Internet Protocol Version 4 (TCP/IPv4) andclick Properties.
Select Use the following IP address and enter the values in IP address, Subnet mask, Default gateway, and Preferred DNS server.
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:
On the client computer, click Control Panel, then click Network and Sharing Center or Network Connections.
Local Area Connection and click ViewStatus.
Click Internet Protocol Version 4 (TCP/IPv4) click Properties.
.Select Obtain an IP address automatically.
.Click OK. Top of sectionTop of section
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.
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). Top of sectionTop of section 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.
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. Top of sectionTop of section Revisions •
V1.0 (February 12, 2008): Bulletin published.