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  Microsoft Windows 2000 Active Directory buffer overflow

From:MICROSOFT <secure_(at)_microsoft.com>
Date:14.10.2008
Subject:Microsoft Security Bulletin MS08-060 – Critical Vulnerability in Active Directory Could Allow Remote Code Execution (957280)

Microsoft Security Bulletin MS08-060 – Critical
Vulnerability in Active Directory Could Allow Remote Code Execution (957280)
Published: October 14, 2008

Version: 1.0
General Information
Executive Summary

This security update resolves a privately reported vulnerability in implementations of Active Directory on Microsoft Windows 2000 Server. The vulnerability could allow remote code execution if an attacker gains access to an affected network. This vulnerability only affects Microsoft Windows 2000 servers configured to be domain controllers. If a Microsoft Windows 2000 server has not been promoted to a domain controller, it will not be listening to Lightweight Directory Access Protocol (LDAP) or LDAP over SSL (LDAPS) queries, and will not be exposed to this vulnerability.

This security update is rated Critical for implementations of Active Directory on Microsoft Windows 2000 Server. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by correctly allocating memory for client LDAP requests. 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 immediately.

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
Operating System Component Maximum Security Impact Aggregate Severity Rating Bulletins Replaced by this Update

Microsoft Windows 2000 Server Service Pack 4


Active Directory


Remote Code Execution


Critical


MS08-035

Non-Affected Software
Operating System Component

Microsoft Windows 2000 Professional Service Pack 4


Not applicable

Windows XP Service Pack 2 and Windows XP Service Pack 3


ADAM

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


ADAM

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


Active Directory
ADAM

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


Active Directory
ADAM

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


Not applicable

Windows Vista and Windows Vista Service Pack 1


Not applicable

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


Not applicable

Windows Server 2008 for 32-bit Systems


Active Directory
AD LDS

Windows Server 2008 for x64-based Systems


Active Directory
AD LDS

Windows Server 2008 for Itanium-based Systems


Active Directory
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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 957280.

I am running one of the platforms that are listed in the affected software table. Why am I not being offered the update?
The update will only be offered to systems on which the affected component is both installed and enabled. Microsoft Windows 2000 Server systems not configured in the role of a domain controller are not affected and will not receive this update.

Does this issue also affect Active Directory Application Mode (ADAM) or Active Directory Lightweight Directory Service (AD LDS)?
No. This issue only affects Microsoft Windows 2000 servers configured as Active Directory domain controllers. No other platforms or services are affected.

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 Active Directory Overflow Vulnerability - CVE-2008-4023 Aggregate Severity Rating

Active Directory on Microsoft Windows 2000 Server Service Pack 4


Critical
Remote Code Execution


Critical
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Active Directory Overflow Vulnerability - CVE-2008-4023

A remote code execution vulnerability exists in implementations of Active Directory on Microsoft Windows 2000 Server. The vulnerability is due to incorrect memory allocation when receiving specially crafted LDAP or LDAPS requests. An attacker who successfully exploited this vulnerability could take complete control of an affected system.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-4023.

Mitigating Factors for Active Directory Overflow Vulnerability - CVE-2008-4023

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:


For customers who require the affected component, 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 vulnerability only affects Microsoft Windows 2000 servers configured to be domain controllers. If a Microsoft Windows 2000 server has not been promoted to a domain controller, it will not be listening to LDAP or LDAPS queries, and will not be exposed to this vulnerability.

To confirm whether a server is listening to LDAP or LDAPS queries, run the following command from an administrator command prompt and look to see if it is listening on the LDAP port (389) or the LDAPS port (636):

netstat –a

LDAP is enabled if the results contain the following:

Proto Local Address Foreign Address State
TCP 0.0.0.0:389 0.0.0.0:0 LISTENING
TCP 0.0.0.0:636 0.0.0.0:0 LISTENING

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Workarounds for Active Directory Overflow Vulnerability - CVE-2008-4023

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:


Block TCP ports 389 and 636 at the perimeter firewall

These ports are used to initiate a connection with the affected component. Blocking it at the enterprise firewall, both inbound and outbound, will help prevent systems that are behind that firewall from attempts to exploit this vulnerability. We recommend that you block all unsolicited inbound communication from the Internet to help prevent attacks that may use other ports. For more information about ports, see TCP and UDP Port Assignments. For more information about the Windows Firewall, see How to Configure Windows Firewall on a Single Computer.
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FAQ for Active Directory Overflow Vulnerability - CVE-2008-4023

What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could take complete control of an affected system remotely. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

Note. Attacks attempting to exploit this vulnerability could also result in a denial of service condition. An attacker could also exploit this vulnerability to force the system to restart. However, since remote code execution is possible, the aggregate scope is larger than only a denial of service.

What causes the vulnerability?
The LDAP service incorrectly allocates memory for specially crafted LDAP requests.

What is Active Directory?
The main purpose of Active Directory is to provide central authentication and authorization services for Windows-based computers.

What is LDAP?
Lightweight Directory Access Protocol (LDAP) is an open network protocol standard designed to provide access to distributed directories.

What is LDAP over SSL?
By default, LDAP traffic is transmitted unsecured. However, it is possible to make LDAP traffic confidential and secure by using Secure Sockets Layer (SSL) / Transport Layer Security (TLS) technology. Administrators can enable LDAP over SSL (LDAPS) by installing a properly formatted certificate from either a Microsoft certification authority (CA) or a non-Microsoft CA, according to the guidelines in Microsoft Knowledge Base Article 321051.

Is LDAP over SSL available by default?
No. Before an LDAP server can participate in an SSL session, the administrator must have obtained a digital certificate and installed it on the server. Unless this has been done, LDAP over SSL is not available.

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 sending a specially crafted LDAP packet to a Microsoft Windows 2000 Domain Controller. Any anonymous user with access to the target network could deliver a specially crafted network packet to the affected system in order to exploit this vulnerability.

What systems are primarily at risk from the vulnerability?
LDAP is a requirement for Active Directory. Any Microsoft Windows 2000 Server that is running as an Active Directory Server is affected by this vulnerability.

What does the update do?
The update addresses the vulnerability by correctly allocating memory for specially crafted client LDAP requests.

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.

Other Information
Acknowledgments

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


Paul Miseiko of nCircle for reporting the Active Directory Overflow Vulnerability (CVE-2008-4023)
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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 (October 14, 2008): Bulletin published.

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