__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft Buffer Overflow in ISA Server 2000 [MS04-001] January 13, 2004 20:00 GMT Number O-051 ______________________________________________________________________________ PROBLEM: A security vulnerability exists in the H.323 filter for Microsoft Internet Security and Acceleration Server (ISA) 2000 that could allow an attacker to overflow a buffer in the Microsoft Firewall Service in Microsoft Internet Security and Acceleration Server (ISA) 2000. PLATFORM: Microsoft Internet Security and Acceleration Server 2000 Microsoft Small Business Server 2000 (which includes Microsoft Internet Security and Acceleration Server 2000) Microsoft Small Business Server 2003 (which includes Microsoft Internet Security and Acceleration Server 2000) DAMAGE: An attacker could try to run code of their choice in the security context of the Microsoft Firewall Service. This would give the attacker complete control over the system. SOLUTION: Install the security update immediately. ______________________________________________________________________________ VULNERABILITY The risk is HIGH. An attacker could try to run code of their ASSESSMENT: choice in the security context of the Microsoft Firewall Service. This would give the attacker complete control over the system. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/o-051.shtml ORIGINAL BULLETIN: Microsoft Security Bulletin MS04-001 http://www.microsoft.com/technet/treeview/default.asp?url= /technet/security/bulletin/MS04-001.asp CVE/CAN: http://www.cve.mitre.org/cgi-bin/cvename.cgi?name= CVE-2003-0819 ______________________________________________________________________________ [***** Start MS04-001 *****] Microsoft Security Bulletin MS04-001 Vulnerability in Microsoft Internet Security and Acceleration Server 2000 H.323 Filter Could Allow Remote Code Execution (816458) Issued: January 13, 2004 Version: 1.0 Summary Who should read this document: Customers who use Microsoft® Internet Security and Acceleration Server 2000 Impact of vulnerability: Remote Code Execution Maximum Severity Rating: Critical Recommendation: Customers should install the security update immediately Update Replacement: None Caveats: None Tested Software and Security Update Download Locations: Affected Software: * Microsoft Internet Security and Acceleration Server 2000 - Download the update * Microsoft Small Business Server 2000 (which includes Microsoft Internet Security and Acceleration Server 2000) – Download the Update * Microsoft Small Business Server 2003 (which includes Microsoft Internet Security and Acceleration Server 2000) – Download the Update Non Affected Software: * Microsoft Proxy Server 2.0 The software listed above has been tested to determine if the versions are affected. Other versions either no longer include security patch support or may not be affected. Please review the Microsoft Support Lifecycle Web site to determine the support lifecycle for your product and version. Technical Details Technical description: A security vulnerability exists in the H.323 filter for Microsoft Internet Security and Acceleration Server 2000 that could allow an attacker to overflow a buffer in the Microsoft Firewall Service in Microsoft Internet Security and Acceleration Server 2000. An attacker who successfully exploited this vulnerability could try to run code of their choice in the security context of the Microsoft Firewall Service. This would give the attacker complete control over the system. The H.323 filter is enabled by default on servers running ISA Server 2000 computers that are installed in integrated or firewall mode. Mitigating factors: * ISA Servers running in cache mode are not vulnerable because the Microsoft Firewall Service is disabled by default * Users can prevent the risk of attack by disabling the H.323 filter Severity Rating: ********************************************************************* Microsoft Internet Security and Acceleration Server 2000 Critical ********************************************************************* The above assessment is based on the types of systems that are affected by the vulnerability, their typical deployment patterns, and the effect that exploiting the vulnerability would have on them. Vulnerability identifier: CAN-2003-0819 Workarounds Microsoft has tested the following workarounds. These workarounds will not correct the underlying vulnerability however they help block known attack vectors. Workarounds may cause a reduction in functionality in some cases – in such situations this is identified below. * Disable the H.323 filter. To disable the H.323 filter, follow these steps: 1. Open ISA management tool. Expand the Extensions container, expand the Application Filters container. 2. Select the H.323 Filter and then click Disable. 3. Restart the Microsoft Firewall Service Windows Components. Impact of workaround: If the H.323 filter is disabled, H.323 traffic is blocked by the Microsoft Firewall Service. This stops any applications that use the H.323 protocol for Internet Protocol (IP) telephony or data collaboration from communicating through the ISA Sever. If H.323 traffic is not on the network with the ISA Server, disabling this filter and other unused filters is recommended for enhanced security and performance. * Block TCP port 1720 at a perimeter or gateway router. By default the H.323 filter listens on external Transmission Control Protocol (TCP) port 1720. Blocking this port at a perimeter router will help to protect the ISA Server from an Internet-based attack. Note: Clicking to clear the Allow Incoming Calls check box on the Call Control tab of the H.323 filter settings does not configure the filter to stop listening on the external TCP port 1720 and is not an effective w orkaround. This behavior has been changed in this Security Update and is documented additionally in the “Frequently Asked Questions” section of this security bulletin. Impact of workaround: If port 1720 traffic is blocked, applications that use the H.323 protocol for IP telephony or data collaboration can no longer be able to communicate over the Internet. Security Update Information * ISA Server 2000, ISA Server 2000 Feature Pack 1, Small Business Server 2000, Small Business Server 2000 Service Pack 1, Small Business Server 2003 Acknowledgments Microsoft thanks the following for working with us to help protect customers: * The UK National Infrastructure Security Co-ordination Centre (NISCC) for reporting the issue described in MS04-001. Obtaining other security updates: Updates for other security issues are available from the following locations: * Security updates are available from the Microsoft Download Center, and can be most easily found by doing a keyword search for "security_patch". * Updates for consumer platforms are available from the WindowsUpdate Web site. Support: * Technical support is available from Microsoft Product Support Services at 1-866-PCSAFETY for customers in the U.S. and Canada. There is no charge for support calls that are associated with security updates. * International customers can get support from their local Microsoft subsidiaries. There is no charge for support associated with security updates. Information on how to contact Microsoft support is available at the International Support Web Site. Security Resources: * The Microsoft TechNet Security Web Site provides additional information about security in Microsoft products. * Microsoft Software Update Services * Microsoft Baseline Security Analyzer (MBSA): Please view Knowledge Base Article 306460 for list of security updates that have detection limitations with the MBSA tool. * Windows Update * Windows Update Catalog: Please view Knowledge Base Article 323166 for more information on the Windows Update Catalog. * Office Update Systems Management Server (SMS): Systems Management Server can provide assistance deploying this security update. For information about Systems Management Server visit the SMS Web Site. SMS also provides several additional tools to assist administrators in the deployment of security updates such as the SMS 2.0 Software Update Services Feature Pack and the SMS 2.0 Administration Feature Pack. The SMS 2.0 Software Update Services Feature Pack utilizes the Microsoft Baseline Security Analyzer and the Microsoft Office Detection Tool to provide broad support for security bulletin remediation. Some software updates may require administrative rights following a restart of the computer Note: The inventory capabilities of the SMS 2.0 Software Update Services Feature Pack may be used for targeting updates to specific computers, and the SMS 2.0 Administration Feature Pack’s Elevated Rights Deployment Tool can be used for installation. This provides optimal deployment for updates that require explicit targeting using Systems Management Server and administrative rights after the computer has been restarted. 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 (January 13, 2004): Bulletin published [***** End MS04-001 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Microsoft for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. 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