__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft Update for IIS 4.0 (841373) [Microsoft Security Bulletin MS04-021] July 14, 2004 12:00 GMT Number O-179 [REVISED 22 Jul 2004] ______________________________________________________________________________ PROBLEM: An unchecked buffer in the Microsoft Internet Information Server version 4.0 redirect function was discovered. IIS 4.0 is available as part of the Windows NT 4.0 Server Option Pack. PLATFORM: Microsoft Windows NTฎ Workstation 4.0 Service Pack 6a Microsoft Windows NT Server 4.0 Service Pack 6a Microsoft Internet Information Server (IIS) 4.0 DAMAGE: An attacker who successfully exploited this buffer overrun vulnerability could take complete control of an affected system, including installing programs; viewing, changing, or deleting data; or creating new accounts that have full privileges. SOLUTION: Apply security updates. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. A remote attacker may gain root level ASSESSMENT: privileges. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/o-179.shtml ORIGINAL BULLETIN: Microsoft Security Bulletin MS04-021 http://www.microsoft.com/technet/security/bulletin/ms04- 021.mspx ADDITIONAL LINKS: Microsoft Knowledge Base Article - 873401 http://support.microsoft.com/default.aspx?scid=kb; en-us;873401 CVE/CAN: http://www.cve.mitre.org/cgi-bin/cvename.cgi?name= CAN-2004-0205 ______________________________________________________________________________ REVISION HISTORY: 7/22/04 - Microsoft found that if ISAPI filters are installed, the IIS 4.0 Server may not respond after installing the original patch. Microsoft has released Knowledge Base Article 873401 that gives instructions on how to obtain a fix for this problem. See Additional Links for URL. "Caveats" section updated below. [***** Start Microsoft Security Bulletin MS04-021 *****] Microsoft Security Bulletin MS04-021 Security Update for IIS 4.0 (841373) Issued: July 13, 2004 Updated: July 21, 2004 Version: 1.0 Summary Who should read this document: Customers who use Microsoftฎ Windowsฎ NTฎ 4.0 Impact of Vulnerability: Remote Code Execution Maximum Severity Rating: Important Recommendation: Customers should install the update at the earliest opportunity. Security Update Replacement: None Caveats: Subsequent to the release of this bulletin, Microsoft was informed of an issue regarding installing this security update on systems running ISAPI filters. For more information and a recommended solution for this issue, see Microsoft Knowledge Base Article 873401. Tested Software and Security Update Download Locations: Affected Software: • Microsoft Windows NTฎ Workstation 4.0 Service Pack 6a – Download the update • Microsoft Windows NT Server 4.0 Service Pack 6a – Download the update Non-Affected Software: • Microsoft Windows 2000 Service Pack 2, Microsoft Windows 2000 Service Pack 3, Microsoft Windows 2000 Service Pack 4 • Microsoft Windows XP and Microsoft Windows XP Service Pack 1 • Microsoft Windows XP 64-Bit Edition Service Pack 1 • Microsoft Windows XP 64-Bit Edition Version 2003 • Microsoft Windows Server™ 2003 • Microsoft Windows Server 2003 64-Bit Edition • Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and Microsoft Windows Millennium Edition (Me) Tested Microsoft Windows Components: Affected Components: • Microsoft Internet Information Server (IIS) 4.0 Non-Affected Components: • Microsoft Internet Information Services 5.0 (included with Windows 2000 Server) • Microsoft Internet Information Services 5.1 (included with Windows XP) • Microsoft Internet Information Services 6.0 (included with Windows Server 2003 The software in this list has been tested to determine if the versions are affected. Other versions either no longer include security update support or may not be affected. To determine the support lifecycle for your product and version, visit the following Microsoft Support Lifecycle Web site. Top of section General Information Executive Summary Executive Summary: This update resolves a newly-discovered, privately reported vulnerability. An attacker who successfully exploited this vulnerability could take complete control of an affected system, including installing programs; viewing, changing, or deleting data; or creating new accounts that have full privileges. Customers should install the update at the earliest opportunity. Severity Ratings and Vulnerability Identifiers: Vulnerability Identifiers Impact of Vulnerability Windows NT 4.0 IIS Redirection Vulnerability - CAN-2004-0205 Remote Code Execution Important This 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. Top of section Vulnerability Details IIS Redirection Vulnerability - CAN-2004-0205: A buffer overrun vulnerability exists in Internet Information Server 4.0 that could allow remote code execution on an affected system. An attacker who successfully exploited this vulnerability could take complete control of the affected system. Mitigating Factors for IIS Redirection Vulnerability - CAN-2004-0205: • Internet Information Server 5.0, Internet Information Server 5.1, and Internet Information Server 6.0 are not affected by this vulnerability. • Customers who have disabled permanent redirects are not at risk from this vulnerability. Top of section Workarounds for IIS Redirection Vulnerability - CAN-2004-0205: Microsoft has tested the following workarounds. While these workarounds will not correct the underlying vulnerability, they help block known attack vectors. When a workaround reduces functionality, it is identified below. • Disable permanent redirects 1. Open the IIS Configuration manager. 2. Right-click the Web site that you want to administer, and then click Properties. 3. Click Home Directory. 4. Uncheck A permanent redirection for this resource, and then click OK. Impact of Workaround: The server will no longer perform redirects. • Use URLScan to disallow the use of large requests 1. Visit the following Web site to Download and install the URLScan security tool. 2. Start Notepad, and then open the %systemroot%\winnt\urlscan\UrlScan.ini file. 3. Configure the MaxUrl setting so that it limits requests to 16 kilobytes (KB). To configure the MaxUrl setting to that it limits requests to 16 KB, add the following line to the RequestLimits section of the file: MaxUrl = 16384 4. Save, and then close the UrlsScan.ini file. 5. Start, and then stop the World Wide Web Publishing Service by using the Services item in Control Panel. You can also do this by using the net stop IIsadmin command and the net start w3svc command at a command prompt. For information about how to do this, see Microsoft Knowledge Base Article 185382 Impact of workaround: The URLScan tool will block all the incoming requests that are larger than 16 KB. • Reduce MaxClientRequestBuffer 1. Start Registry Editor (Regedt32.exe). 2. Locate the following key in the registry: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\w3svc\parameters 3. Click Edit, click Add Value, and then add the following registry value: • Value Name: MaxClientRequestBufferData Type: REG_DWORD 4. In the DWORD Editor dialog box, under Radix, click Decimal. 5. In the Data box, type the number of bytes for the maximum URL request. Set the size so that it is equal to or less than 16384 bytes. Note You must restart the IIS service for the changes to take effect. For more information, see Microsoft Knowledge Base Article 260694 Impact of workaround: Any incoming request that is larger than 16384 bytes will fail. • Stop, disable, or remove IIS • You can stop the World Wide Web Publishing Service component of IIS by issuing the net stop w3svc command at a command prompt. • You can use the IIS Manager to disable or stop IIS. • You can stop or disable the World Wide Web Publishing Service by using the Services item in Control Panel. • You can use Add or Remove Programs in Control Panel to remove IIS from your system. To find IIS, click Add/Remove Windows Components. Impact of Workaround: If you stop the World Wide Web Publishing Service component of IIS, the system can no longer provide Web content. If you stop or remove IIS, the system can no longer provide Web, File Transfer Protocol (FTP), or NTP content. The Simple Mail Transfer Protocol (SMTP) service will also be unavailable. Top of section FAQ for IIS Redirection Vulnerability - CAN-2004-0205: Top of section Security Update Information Installation Platforms and Prerequisites: For information about the specific security update for your platform, click the appropriate link: Windows NT 4.0 (all versions) Top of section Obtaining Other Security Updates: Updates for other security issues are available from the following locations: • Security updates are available from the Microsoft Download Center: You can find them most easily by doing a keyword search for "security_patch". • Updates for consumer platforms are available from the Windows Update Web site. 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. 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) • Windows Update • Windows Update Catalog: For more information about the Windows Update Catalog, see Microsoft Knowledge Base Article 323166. • Office Update Software Update Services: By using Microsoft Software Update Services (SUS), administrators can quickly and reliably deploy the latest critical updates and security updates to Windows 2000 and Windows Server 2003-based servers, and to desktop systems that are running Windows 2000 Professional or Windows XP Professional. For more information about how to deploy this security update with Software Update Services, visit the Software Update Services Web site. Systems Management Server: Microsoft Systems Management Server (SMS) delivers a highly-configurable enterprise solution for managing updates. By using SMS, administrators can identify Windows-based systems that require security updates and to perform controlled deployment of these updates throughout the enterprise with minimal disruption to end users. For more information about how administrators can use SMS 2003 to deploy security updates, see the SMS 2003 Security Patch Management Web site. SMS 2.0 users can also use Software Updates Service Feature Pack to help deploy security updates. For information about SMS, visit the SMS Web site. Note SMS uses the Microsoft Baseline Security Analyzer and the Microsoft Office Detection Tool to provide broad support for security bulletin update detection and deployment. Some software updates may not be detected by these tools. Administrators can use the inventory capabilities of the SMS in these cases to target updates to specific systems. For more information about this procedure, see the following Web site. Some security updates require administrative rights following a restart of the system. Administrators can use the Elevated Rights Deployment Tool (available in the SMS 2003 Administration Feature Pack and in the SMS 2.0 Administration Feature Pack) to install these updates. 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 13, 2004): Bulletin published • V1.1 (July 21, 2004): Updated Registry Key Verification section. Updated Caveats section to reflect the availability of Microsoft Knowledge Base Article 873401. [***** End Microsoft Security Bulletin MS04-021 *****] _______________________________________________________________________________ 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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