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SecurityvulnsSECURITYVULNS:DOC:21453

HistoryMar 10, 2009 - 12:00 a.m.

Microsoft Security Bulletin MS09-008 – Important Vulnerabilities in DNS and WINS Server Could Allow Spoofing (962238)

2009-03-1000:00:00

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Microsoft Security Bulletin MS09-008 – Important
Vulnerabilities in DNS and WINS Server Could Allow Spoofing (962238)
Published: March 10, 2009

Version: 1.0
General Information
Executive Summary

This security update resolves two privately reported vulnerabilities and two publicly disclosed vulnerabilities in Windows DNS server and Windows WINS server. These vulnerabilities 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 Server, 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 correcting the way that Windows DNS servers cache and validate queries, and by modifying the way that Windows DNS servers and Windows WINS servers handle WPAD and ISATAP registration. 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 294781.

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

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

Known Issues. None
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Affected and Non-Affected Software

The following software have been tested to determine which versions or editions are affected. Other versions or editions are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, visit Microsoft Support Lifecycle.

Affected Software
DNS Server WINS Server Maximum Security Impact Aggregate Severity Rating Bulletins Replaced by this Update

DNS server on Microsoft Windows 2000 Server Service Pack 4
(961063)

See row below

Spoofing

Important

MS08-037

See row above

WINS server on Microsoft Windows 2000 Server Service Pack 4
(961064)

Spoofing

Important

MS08-034

DNS server on Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2
(961063)

See row below

Spoofing

Important

MS08-037,
MS08-066

See row above

WINS server on Windows Server 2003 Service Pack 1 and Windows Server 2003 Service Pack 2
(961064)

Spoofing

Important

MS08-034

DNS server on Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2
(961063)

See row below

Spoofing

Important

MS08-037,
MS08-066

See row above

WINS server on Windows Server 2003 x64 Edition and Windows Server 2003 x64 Edition Service Pack 2
(961064)

Spoofing

Important

MS08-034

DNS server on Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems
(961063)

See row below

Spoofing

Important

MS08-037,
MS08-066

See row above

WINS server on Windows Server 2003 with SP1 for Itanium-based Systems and Windows Server 2003 with SP2 for Itanium-based Systems
(961064)

Spoofing

Important

MS08-034

DNS server on Windows Server 2008 for 32-bit Systems*
(961063)

Not applicable

Spoofing

Important

MS08-037

DNS server on Windows Server 2008 for x64-based Systems*
(961063)

Not applicable

Spoofing

Important

MS08-037

*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 2000 Professional Service Pack 4

Windows XP Service Pack 2 and Windows XP Service Pack 3

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

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

Where are the file information details?
The file information details can be found in Microsoft Knowledge Base Article 962238.

Why does this bulletin contain two updates for each affected operating system?
This bulletin contains two updates, identified by KB number, for each affected operating system because the modifications that are required to address the vulnerabilities are located in separate components. Customers need to install security update package 961063 for each DNS server and 961064 for each WINS server in their environment.

Why does this update address several reported security vulnerabilities?
This update contains support for several vulnerabilities because the modifications that are required to address these issues are located in related files. Instead of having to install several updates that are almost the same, customers need to install this update only.

I am using an older release of the software discussed in this security bulletin. What should I do?
The affected software listed in this bulletin have been tested to determine which releases are affected. Other releases are past their support life cycle. To determine the support life cycle for your software release, visit Microsoft Support Lifecycle.

It should be a priority for customers who have older releases of the software to migrate to supported releases to prevent potential exposure to vulnerabilities. For more information about the Windows Product Lifecycle, visit Microsoft Support Lifecycle. For more information about the extended security update support period for these software versions or editions, visit Microsoft Product Support Services.

Customers who require custom support for older releases must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers without an Alliance, Premier, or Authorized Contract can contact their local Microsoft sales office. For contact information, visit Microsoft Worldwide Information, select the country, and then click Go to see a list of telephone numbers. When you call, ask to speak with the local Premier Support sales manager. For more information, see the Windows Operating System Product Support Lifecycle FAQ.
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Vulnerability Information

Severity Ratings and Vulnerability Identifiers

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the March bulletin summary. For more information, see Microsoft Exploitability Index.
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software DNS Server Query Validation Vulnerability - CVE-2009-0233 DNS Server Response Validation Vulnerability - CVE-2009-0234 DNS Server Vulnerability in WPAD Registration Vulnerability- CVE-2009-0093 WPAD WINS Server Registration Vulnerability - CVE-2009-0094 Aggregate Severity Rating

Microsoft Windows 2000 Server Service Pack 4

Important
Spoofing

Important

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

Important
Spoofing

Important

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

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

Windows Server 2008 for 32-bit Systems*

Important
Spoofing

Not applicable

Important

Windows Server 2008 for x64-based Systems*

Important
Spoofing

Not applicable

Important

DNS Server Query Validation Vulnerability - CVE-2009-0233

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

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2009-0233.

Mitigating Factors for DNS Server Query Validation Vulnerability - CVE-2009-0233

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:
•

Sites using SSL/TLS are not affected by this vulnerability.
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Workarounds for DNS Server Query Validation Vulnerability - CVE-2009-0233

Microsoft has not identified any workarounds for this vulnerability.
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FAQ for DNS Server Query Validation Vulnerability - CVE-2009-0233

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

What causes the vulnerability?
Windows DNS server does not reuse cached responses when receiving specifically crafted queries thereby allowing greater predictability of subsequent transaction IDs used by the DNS server.

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 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?
Windows DNS servers that are using dynamic updates that do not have pre-existing ISTAP or WPAD registered are the systems at risk for this vulnerability.

What does the update do?
The update removes this vulnerability by correcting the way that Windows DNS server validates specifically crafted 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 Server Response Validation Vulnerability - CVE-2009-0234

A response validation vulnerability exists in Windows DNS Server. The vulnerability could allow an unauthenticated remote attacker to send specially crafted queries to a DNS server so as to allow greater predictability of transaction IDs used by the DNS server and thus to redirect Internet traffic from legitimate locations.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2009-0234.

Mitigating Factors for DNS Server Response Validation Vulnerability - CVE-2009-0234

Sites using SSL/TLS are not affected by this vulnerability.
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Workarounds for DNS Server Response Validation Vulnerability - CVE-2009-0234

Microsoft has not identified any workarounds for this vulnerability.
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FAQ for DNS Server Response Validation Vulnerability - CVE-2009-0234

What is the scope of the vulnerability?
A spoofing vulnerability exists in Windows DNS server. This vulnerability could allow a remote unauthenticated attacker to have greater predictability of transaction IDs used by the DNS server, and thus facilitate DNS cache poisoning and redirection of Internet traffic.

What causes the vulnerability?
Windows DNS server does not correctly cache specifically crafted DNS responses. This results in the DNS server making unnecessary lookups and leads to greater predictability of subsequent transaction IDs used by the DNS server.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability in conjunction with other DNS cache vulnerabilities could poison the DNS cache and redirect internet traffic.

How could an attacker exploit the vulnerability?
An attacker who successfully exploited this vulnerability could send multiple specifically crafted queries to the DNS server. As a result, the DNS server would make unnecessary lookups and thereby allow for greater predictability of subsequent transaction IDs used by the server.

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

What does the update do?
The update removes this vulnerability by correcting the way that Windows DNS servers cache and validate responses.

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

DNS Server Vulnerability in WPAD Registration Vulnerability- CVE-2009-0093

A man-in-the-middle attack vulnerability exists in Windows DNS servers where dynamic update is used and ISATAP and WPAD are not already registered in DNS. This vulnerability could allow a remote authenticated attacker to spoof a web proxy thereby redirect Internet traffic to an address of the attacker’s choice.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2009-0093.

Mitigating Factors for DNS Server Vulnerability in WPAD Registration Vulnerability- CVE-2009-0093

If WPAD and ISATAP is already registered on DNS it will not be possible for an attacker to register WPAD as well.
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Workarounds for DNS Server Vulnerability in WPAD Registration Vulnerability- CVE-2009-0093

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:
•

Create a WPAD.DAT Proxy Auto Configuration File on a Host Named WPAD in Your Organization to Direct Web Browsers to Your Organization’s Proxy

To create a WPAD.DAT proxy auto configuration file, follow these steps:

Create a WPAD.DAT file that adheres to the Proxy auto-config specification. For more information on Proxy Auto-Configuration (PAC) files including a sample file, see the following MSDN article.

Place the WPAD.DAT file in the root directory of a web server in your organization and ensure the file can be requested anonymously.

Create a MIME type for the WPAD.DAT file on the web server of "application/x-ns-proxy-autoconfig".

Create the appropriate entries in your organizations DHCP or DNS server to allow discovery of the WPAD server.

For information on how to register WPAD, see Microsoft Knowledgebase Article 934864.

Impact of workaround. None
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FAQ for DNS Server Vulnerability in WPAD Registration Vulnerability- CVE-2009-0093

What is the scope of the vulnerability?
A spoofing vulnerability exists in Windows DNS server. An attacker who successfully exploited this vulnerability could redirect Internet traffic.

What causes the vulnerability?
The Windows DNS server does not correctly validate who can register WPAD entries on the DNS server. By default a DNS server will allow any user to create a registration in the DNS database for WPAD if the name registration does not already exist.

What is Web Proxy Auto-Discovery (WPAD)?
The Web Proxy Auto-Discovery (WPAD) feature enables web clients to automatically detect proxy settings without user intervention. The WPAD feature prepends the hostname "wpad" to the fully-qualified domain name and progressively removes subdomains until it finds a WPAD server answering the domain name. For more information, see WinHTTP AutoProxy Support.

What is Dynamic Update?
Dynamic update enables DNS client computers to register and dynamically update their resource records with a DNS server whenever changes occur. This reduces the need for manual administration of zone records, especially for clients that frequently move or change locations and use DHCP to obtain an IP address. For more information, see the dynamic update TechNet article.

What is ISATAP?
The Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) provides IPv6 connectivity within an IPv4 Intranet. For information on ISATAP, see RFC4214: Intra-Site Automatic Tunnel Addressing Protocol (ISATAP).

What might an attacker use the vulnerability to do?
An attacker who has successfully exploited this vulnerability could spoof the legitimate web proxy and intercept or redirect internet traffic.

How could an attacker exploit the vulnerability?
If an attacker registers "WPAD" in the DNS database and points it to an IP address that the attacker controls, it would allow the attacker to conduct man-in-the-middle (MITM) attacks against any browsers configured to use WPAD to discover proxy server settings.

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

What does the update do?
The update removes this vulnerability by modifying the way that Windows DNS servers respond to WPAD name resolution requests.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
Yes. This vulnerability has been publicly disclosed. It has been assigned Common Vulnerability and Exposure number CVE-2009-0093.

WPAD WINS Server Registration Vulnerability - CVE-2009-0094

A man-in-the-middle attack vulnerability exists in Windows WINS servers. This vulnerability could allow a remote authenticated attacker to spoof a web proxy and thereby redirect Internet traffic to an address of the attacker’s choice.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2009-0094.

Mitigating Factors for WPAD WINS Server Registration Vulnerability - CVE-2009-0094

If WINS server already has WPAD and ISATAP registered than an attacker will not be able to register these as well.
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Workarounds for WPAD WINS Server Registration Vulnerability - CVE-2009-0094

Create a WPAD.DAT Proxy Auto Configuration File on a Host Named WPAD in Your Organization to Direct Web Browsers to Your Organization’s Proxy

To create a WPAD.DAT proxy auto configuration file, follow these steps:

Create a WPAD.DAT file that adheres to the Proxy auto-config specification. For more information on Proxy Auto-Configuration (PAC) files including a sample file, see the following MSDN article.

Place the WPAD.DAT file in the root directory of a web server in your organization and ensure the file can be requested anonymously.

Create a MIME type for the WPAD.DAT file on the web server of "application/x-ns-proxy-autoconfig".

Create the appropriate entries in your organizations DHCP or DNS server to allow discovery of the WPAD server.

For information on how to register WPAD, see Microsoft Knowledgebase Article 934864.

Impact of workaround. None
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FAQ for WPAD WINS Server Registration Vulnerability - CVE-2009-0094

What is the scope of the vulnerability?
A spoofing vulnerability exists in Windows WINS server. An attacker who successfully exploited this vulnerability could redirect internet traffic.

What causes the vulnerability?
The Windows WINS server does not correctly validate who can register WPAD or ISATAP entries on the WINS server. By default a WINS server will allow any user to create a registration in the WINS database for WPAD or ISATAP if the name registration does not already exist.

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

What might an attacker use the vulnerability to do?
An attacker who has successfully exploited this vulnerability could spoof the legitimate web proxy or ISATAP route and intercept or redirect Internet traffic.

How could an attacker exploit the vulnerability?
If an attacker registers WPAD or ISATP in the WINS database and points it to an IP address they control, it would allow the attacker to conduct man-in-the-middle (MITM) attacks against any browsers configured to use WPAD to discover proxy server settings.

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

What does the update do?
The update removes this vulnerability by modifying the way that Windows WINS servers responds to WPAD and ISATAP name resolution requests.

Other Information
Acknowledgments

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

Kevin Day for working with us on the DNS Server Query Vulnerability (CVE-2009-0233) and the DNS Server Response Validation Vulnerability (CVE-2009-0234).
•

Dave Dagon for working with us on the DNS Server Query Vulnerability (CVE-2009-0233) and the DNS Server Response Validation Vulnerability (CVE-2009-0234)

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 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 (March 10, 2009): Bulletin published.