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HistoryJul 09, 2008 - 12:00 a.m.

Microsoft Security Bulletin MS08-037 – Important Vulnerabilities in DNS Could Allow Spoofing (953230)

2008-07-0900:00:00
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Microsoft Security Bulletin MS08-037 – Important
Vulnerabilities in DNS Could Allow Spoofing (953230)
Published: July 8, 2008

Version: 1.0
General Information
Executive Summary

This security update resolves two privately reported vulnerabilities in the Windows Domain Name System (DNS) that could allow spoofing. These vulnerabilities exist in both the DNS client and DNS server and could allow a remote attacker to redirect network traffic intended for systems on the Internet to the attacker’s own systems.

This security update is rated Important for all supported editions of Microsoft Windows 2000, Windows XP, Windows Server 2003, and Windows Server 2008. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerabilities by using strongly random DNS transaction IDs, using random sockets for UDP queries, and updating the logic used to manage the DNS cache. 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. Microsoft Knowledge Base Article 953230 documents the currently known issues that customers may experience when they install this security update.
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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
DNS Client DNS Server Maximum Security Impact Aggregate Severity Rating Bulletins Replaced by this Update

Microsoft Windows 2000 Service Pack 4

Microsoft Windows 2000 Server Service Pack 4

Spoofing

Important

None

Windows XP Service Pack 2 and Windows XP Service Pack 3

Not applicable

Spoofing

Important

None

Windows XP Professional x64 Edition and Windows XP Professional x64 Edition Service Pack 2

Not applicable

Spoofing

Important

None

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

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

Spoofing

Important

None

Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Spoofing

Important

None

Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems

Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems

Spoofing

Important

None

Not applicable

Windows Server 2008 for 32-bit Systems*

Spoofing

Important

None

Not applicable

Windows Server 2008 for x64-based Systems*

Spoofing

Important

None

*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 Vista and Windows Vista Service Pack 1

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

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

What are the uninstall issues that customers may experience after installing these security updates?
Supported editions of Microsoft Windows 2000 and Windows 2003 systems will receive the DNS server update as well as the DNS client updates. The DNS server update and the DNS client updates share binaries and must be uninstalled in the reverse order that they were installed to avoid regressing the shared binaries to previous versions. Microsoft Knowledge Base Article 823836 documents the currently known issues that customers may experience when they uninstall these security updates.

What are the random socket connection issues that customers may experience when installing this security update?
By default, the DNS updates offered by this security bulletin will take advantage of a large number of available sockets to offer greater entropy. However, if the user has defined port ranges in the registry, then the updates will respect the user-defined settings and will only allocate the defined sockets.

Socket ranges can be defined in the following registry location:

HKLM\System\CurrentControlSet\Services\DNS\Parameters Reg key Name: SocketPoolSize

Note The DNS service must be restarted to implement these changes.

What does defining the socket pool range do?
It may be necessary to define the range of sockets that DNS can choose from to avoid conflicting with other applications or services that need the same socket pool for their communications. See MaxUserPort and Microsoft Knowledge Base Article 812873 for more details about these registry key settings.

What are the differences between operating systems when defining the socket pool ranges?
The MaxUserPort registry Key has different meanings on Windows Vista and Windows Server 2008 than on Microsoft Windows Server 2000 and Windows Server 2003. Microsoft knowledge Base Article 929851 details the change in behavior for Windows Vista and Windows Server 2008.

In Microsoft Windows Server 2000 and Windows Server 2003, setting the MaxUserPort defines the ending point of the dynamic port range. The range starts at 1024 and continues to the user-defined value in the MaxUserPort registry key setting. After installing the updates offered by this security bulletin, the default behavior on Microsoft Windows Server 2000 and Windows Server 2003 will be to allocate sockets randomly from the port range 49152 to 65535. If the MaxUserPort range has been defined, then ports will be allocated randomly from 1024 to the defined value in the MaxUserPort registry key setting. Visit Microsoft Knowledge Base Article 812873 for more information on reserving port ranges on Microsoft Windows 2000 Server and Windows Server 2003.

In Windows Vista and Windows Server 2008, setting the MaxUserPort defines the starting point of the dynamic port range. By default, the range on Windows Vista and Windows Server 2008 is 49152 to 65535.

Where are the file information details?
The file information details can be found in Microsoft Knowledge Base Article 953230.

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
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software DNS Insufficient Socket Entropy Vulnerability - CVE-2008-1447 DNS Cache Poisoning Vulnerability - CVE-2008-1454 Aggregate Severity Rating

Microsoft Windows 2000 Service Pack 4

Important
Spoofing

Important
Spoofing

Important

Windows XP Service Pack 2 and Windows XP Service Pack 3

Important
Spoofing

Not applicable

Important

Windows XP Professional x64 Edition and Windows XP Professional x64 Edition Service Pack 2

Important
Spoofing

Not applicable

Important

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

Important
Spoofing

Important
Spoofing

Important

Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2

Important
Spoofing

Important
Spoofing

Important

Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems

Important
Spoofing

Important
Spoofing

Important

Windows Server 2008 for 32-bit Systems*

Not applicable

Important
Spoofing

Important

Windows Server 2008 for x64-based Systems*

Not applicable

Important
Spoofing

Important

*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.
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DNS Insufficient Socket Entropy Vulnerability - CVE-2008-1447

A spoofing vulnerability exists in Windows DNS client and Windows DNS server. This vulnerability could allow a remote unauthenticated attacker to quickly and reliably spoof responses and insert records into the DNS server or client cache, thereby redirecting Internet traffic.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-1447.

Mitigating Factors for DNS Insufficient Socket Entropy Vulnerability - CVE-2008-1447

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.

Cryptographic protocols operating above the TCP and IP layers, such as IPsec or SSL/TLS, may prevent an attacker from being able to monitor or interfere with redirected traffic.
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Workarounds for DNS Insufficient Socket Entropy Vulnerability - CVE-2008-1447

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 not identified any workarounds for this vulnerability.
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FAQ for DNS Insufficient Socket Entropy Vulnerability - CVE-2008-1447

What is the scope of the vulnerability?
A spoofing vulnerability exists in Windows DNS client and DNS server. An attacker who successfully exploited this vulnerability could insert arbitrary addresses into the DNS cache.

What causes the vulnerability?
The Windows DNS service in the Windows DNS client and DNS server does not provide enough entropy when performing DNS queries.

What is the Domain Name System (DNS)?
Domain Name System (DNS) is one of the industry-standard suite of protocols that comprise TCP/IP. DNS is implemented using two software components: the DNS server and the DNS client (or resolver). Both components are run as background service applications. Network resources are identified by numeric IP addresses, but these IP addresses are difficult for network users to remember. The DNS database contains records that map user-friendly alphanumeric names for network resources, such as www.microsoft.com, to the IP addresses used by those resources for communication. In this way, DNS acts as a mnemonic device, making network resources easier to remember for network users. For more information and to view logical diagrams illustrating how DNS fits with other Windows technologies, review the article what is DNS.

What is DNS Cache?
Domain Name System (DNS) caching resolver service is a service that saves the responses to DNS queries so that the DNS server is not repeatedly queried for the same information. For more information, see the DNSCache Technet article or the DNS Resolver Cache Service Technet article. See the Attack detection TechNet article for more information on DNS cache poisoning.

What might an attacker use the vulnerability to do?
An attacker who has successfully exploited this vulnerability can insert arbitrary addresses into the DNS cache, also known as DNS cache poisoning.

How could an attacker exploit the vulnerability?
An attacker could send specific queries to a vulnerable DNS server or client, and at the same time respond back in a manner that allows the attacker to insert false or misleading DNS data. The attacker could then redirect Internet traffic from legitimate locations to an address of the attacker’s choice.

What systems are primarily at risk from the vulnerability?
Any Windows system connected to a network or the Internet would be at risk. Windows Vista and Windows Server 2008 are not affected by this vulnerability.

What does the update do?
The update removes this vulnerability by using strongly random DNS transaction ID values and random UDP sockets for remote queries.

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.
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DNS Cache Poisoning Vulnerability - CVE-2008-1454

A cache poisoning vulnerability exists in Windows DNS Server. The vulnerability could allow an unauthenticated remote attacker to send specially crafted responses to DNS requests made by vulnerable systems, thereby poisoning the DNS cache and redirecting Internet traffic from legitimate locations.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-1454.

Mitigating Factors for DNS Cache Poisoning Vulnerability - CVE-2008-1454

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.

Microsoft has not identified any mitigations for this vulnerability.
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Workarounds for DNS Cache Poisoning Vulnerability - CVE-2008-1454

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 not identified any workarounds for this vulnerability.
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FAQ for DNS Cache Poisoning Vulnerability - CVE-2008-1454

What is the scope of the vulnerability?
A cache poisoning vulnerability exists in Windows DNS Server. An attacker who successfully exploited this vulnerability could insert false or misleading DNS data in the response to specific DNS requests, thereby redirecting Internet traffic.

What causes the vulnerability?
Under certain conditions the DNS server accepts records from a response that is outside the remote server’s authority.

What is the Domain Name System (DNS)?
Domain Name System (DNS) is one of the industry-standard suite of protocols that comprise TCP/IP. DNS is implemented using two software components: the DNS server and the DNS client (or resolver). Both components are run as background service applications. Network resources are identified by numeric IP addresses, but these IP addresses are difficult for network users to remember. The DNS database contains records that map user-friendly alphanumeric names for network resources to the IP address used by those resources for communication. In this way, DNS acts as a mnemonic device, making network resources easier to remember for network users. For more information and to view logical diagrams illustrating how DNS fits with other Windows technologies, review the article What is DNS.

What is DNS Cache?
Domain Name System (DNS) caching resolver service is a service that saves the responses to DNS queries so that the DNS server is not repeatedly queried for the same information. For more information, see the DNSCache Technet article or the DNS Resolver Cache Service Technet article. See the Attack detection TechNet article for more information on DNS cache poisoning.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could poison the DNS cache.

How could an attacker exploit the vulnerability?
An attacker who successfully exploited this vulnerability could insert false or misleading DNS data in the response to specific DNS requests, thereby redirecting Internet traffic.

What systems are primarily at risk from the vulnerability?
Windows DNS servers are at risk.

What does the update do?
The update removes the vulnerability by correcting internal DNS processing to avoid cache poisoning.

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.

Other Information
Acknowledgments

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

Dan Kaminsky of IOActive for reporting the DNS Insufficient Socket Entropy Vulnerability (CVE-2008-1447)
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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 (July 8, 2008): Bulletin published.