__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft Unchecked Buffer in Windows Component Could Cause Web Server Compromise [Microsoft Security Bulletin MS03-007] March 17, 2003 16:00 GMT Number N-054 [Revised 23 April 2003] [Revised 28 May 2003] ______________________________________________________________________________ PROBLEM: A vulnerability has been identified in the World Wide Web Distributed Authoring and Versioning (WebDAV) protocol. WebDAV uses IIS to pass requests to and from Windows 2000. When IIS receives a WebDAV request, it typically processes the request and then acts on it. However, if the request is formed in a particular way, a buffer overrun can result because of a flaw in one of the components called by WebDAV which does not correctly check parameters. PLATFORM: Microsoft Windows 2000 running IIS 5.0 DAMAGE: By exploiting the buffer overrun, a remote attacker could gain administrator access to the system. SOLUTION: Apply available patch. ______________________________________________________________________________ VULNERABILITY The risk is HIGH. IIS 5.0 is installed by default on all server ASSESSMENT: versions of Windows 2000. It has been reported that an exploit for this attack exists. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-054.shtml ORIGINAL BULLETIN: http://www.microsoft.com/technet/treeview/default.asp? url=/technet/security/bulletin/MS03-007.asp PATCHES: http://microsoft.com/downloads/details.aspx?FamilyId= C9A38D45-5145-4844-B62E-C69D32AC929B&displaylang=en ____________________________________________________________________________ [***** Start Microsoft Security Bulletin MS03-007 *****] Microsoft Security Bulletin MS03-007 Unchecked Buffer In Windows Component Could Cause Server Compromise (815021) Originally posted: March 17, 2003 Updated: May 28, 2003 Summary Who should read this bulletin: Systems administrators running Microsoft ® Windows ® NT 4.0, Windows 2000, and Windows XP. Impact of vulnerability: Run code of attacker’s choice Maximum Severity Rating: Critical Recommendation: Systems administrators should apply the patch immediately End User Bulletin: An end user version of this bulletin is available at: http://www.microsoft.com/security/security_bulletins/ms03-007.asp Affected Software: * Microsoft Windows NT 4.0 * Microsoft Windows NT 4.0 Terminal Server Edition * Microsoft Windows 2000 * Microsoft Windows XP Not Affected Software: * Microsoft Windows Server 2003 Technical details Technical description: Microsoft originally released this security bulletin on March 17, 2003. At that time, Microsoft was aware of a publicly available exploit that was being used to attack Windows 2000 Servers running IIS 5.0. The attack vector in this case was WebDAV although the underlying vulnerability was in a core operating system component, ntdll.dll. Microsoft issued a patch to protect Windows 2000 customers shortly afterwards, but also continued to investigate the underlying vulnerability. During the course of that investigation, Microsoft found that Windows NT 4.0 also contains the underlying vulnerability in ntdll.dll, however it does not support WebDAV and therefore the known exploit was not effective against Windows NT 4.0. In addition, Microsoft has recently been made aware of this vulnerability as well in Windows XP. However, like Windows NT 4.0, Windows XP does not install Internet Information Services (IIS) by default. Microsoft has now released patches for Windows NT 4.0 and Windows XP. Microsoft Windows 2000 supports the World Wide Web Distributed Authoring and Versioning (WebDAV) protocol. WebDAV, defined in RFC 2518, is a set of extensions to the Hyper Text Transfer Protocol (HTTP) that provide a standard for editing and file management between computers on the Internet. A security vulnerability is present in a Windows component used by WebDAV and results because a core operating system component, ntdll.dll, contains an unchecked buffer. An attacker could exploit the vulnerability by sending a specially formed HTTP request to a machine running Internet Information Server (IIS). The request could cause the server to fail or to execute code of the attacker’s choice. The code would run in the security context of the IIS service (which, by default, runs in the LocalSystem context). Although Microsoft has supplied a patch for this vulnerability and recommends all affected customers install the patch immediately, additional tools and preventive measures have been provided that customers can use to block the exploitation of this vulnerability while they are assessing the impact and compatibility of the patch. These temporary workarounds and tools are discussed in the “Workarounds” section in the FAQ below. Mitigating factors: * URLScan, which is a part of the IIS Lockdown Tool will block this attack in its default configuration * The vulnerability can only be exploited remotely if an attacker can establish a web session with an affected server * Windows NT 4.0 and Windows XP do not install Internet Information Services by default. * Windows NT 4.0 does not support WebDAV Severity Rating: Windows NT 4.0 Important Windows NT 4.0 Terminal Server Edition Important Windows 2000 Critical Windows XP Important The above assessment is based on the types of systems affected by the vulnerability, their typical deployment patterns, and the effect that exploiting the vulnerability would have on them. Vulnerability identifier: CAN-2003-0109 Tested Versions: Microsoft tested Windows NT 4.0, Windows 2000, Windows XP and Windows Server 2003, to assess whether they are affected by this vulnerability. Previous versions are no longer supported, and may or may not be affected by these vulnerabilities. Patch availability Download locations for this patch * Microsoft Windows NT 4.0: * All except NEC and Chinese - Hong Kong * Japanese NEC * Chinese - Hong Kong * Windows NT 4.0, Terminal Server Edition: * All * Microsoft Windows 2000: * All except Japanese NEC * Japanese NEC * Microsoft Windows XP: * 32-bit Edition * 64-bit Edition Additional information about this patch Installation platforms: Windows NT 4.0: This patch can be installed on systems running Windows NT 4.0 Service Pack 6a. Windows 2000: This patch can be installed on systems running Windows 2000 Service Pack 2 or Service Pack 3. Windows XP: This patch can be installed on systems running Windows XP Gold or Service Pack 1. Inclusion in future service packs: The fix for this issue will be included in Windows 2000 Service Pack 4 and Windows XP Service pack 2. Reboot needed: Yes Patch can be uninstalled: Yes Superseded patches: None. Verifying patch installation: * Windows NT 4.0: To verify that the patch has been installed on the machine, confirm that all files listed in the file manifest in Knowledge Base article 815021 are present on the system. * Windows NT 4.0 Terminal Server Edition: To verify that the patch has been installed on the machine, confirm that all files listed in the file manifest in Knowledge Base article 815021 are present on the system. * Windows 2000: To verify that the patch has been installed on the machine, confirm that the following registry key has been created on the machine: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows 2000\SP4\Q815021. To verify the individual files, use the date/time and version information provided in the following registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows 2000\SP4\Q815021\Filelist. * Windows XP: To verify that the patch has been installed on the machine, confirm that the following registry key has been created on the machine: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows XP\SP1\Q815021. To verify the individual files, use the date/time and version information provided in the following registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows XP\SP1\Q815021\Filelist. Caveats: If you are running Windows 2000 SP2, before installing this patch please check the version of ntoskrnl.exe on your system. To verify the version of ntoskrnl.exe on your system, perform the following steps: 1. Browse to the %windir%\system32 directory 2. Right-click ntoskrnl.exe 3. Choose properties. The version information is located on the ‘version’ tab. Versions of ntoskrnl.exe between 5.0.2195.4797 and 5.0.2195.4928 (inclusive) are not compatible with this patch. These versions were only distributed with Product Support Services hotfixes. If the patch for this issue is installed on a system with one of these versions of ntoskrnl.exe, the machine will fail on the first reboot with a Stop 0x00000071 message and will have to be recovered using the Windows 2000 recovery console and the backup copy of ntdll.dll stored in the “\winnt\$NTUninstallQ815021$” directory. To update a system with a version of ntoskrnl.exe distributed from Product Support Services, you must first contact PSS before applying this patch. Information on contacting Product Support Services can be found at: http://support.microsoft.com Alternatively you can upgrade to Windows 2000 SP3 prior to installing this patch or apply the Windows 2000 patch from MS03-013, which superceeds this patch and corrects the problem described above. Localization: Localized versions of this patch are available at the locations discussed in “Patch Availability”. Obtaining other security patches: Patches for other security issues are available from the following locations: * Security patches are available from the Microsoft Download Center, and can be most easily found by doing a keyword search for "security_patch". * Patches for consumer platforms are available from the WindowsUpdate web site Other information: Support: * Microsoft Knowledge Base article 815021 discusses this issue. Additional Knowledge Base articles can be found on the Microsoft Online Support web site. * Technical support is available from Microsoft Product Support Services. There is no charge for support calls associated with security patches. Security Resources: The Microsoft TechNet Security Web Site provides additional information about security in Microsoft products. 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 17, 2003): Bulletin Created. * V1.1 (March 18, 2003): Added new information in the Caveats under in the Additional Information section, clarified affected Windows component throughout the bulletin, added a question regarding IIS 5.0 to the Frequently Asked Questions section, added a question regarding changes to the Caveats in the Additional Information section to the Frequently Asked Questions section. * V2.0 (April 23, 2003): Updated to include details of NT 4.0 patch. * V2.1 (April 24, 2003): Updated to include download link for NT4 package for Japanese NEC * V2.2 (April 24, 2003): Provided additional clarification in FAQ regarding supercedence of Windows 2000 patch by the patch in MS03-013. * V3.0 (May 28, 2003): Updated to include details of Windows XP patch. * V3.1 (May 28, 2003): Updated to include correct Windows NT 4.0 and Windows XP verification keys. * V3.2 (May 28, 2003): Updated frequently asked questions section regarding IIS 5.1 [***** End Microsoft Security Bulletin MS03-007 *****] _______________________________________________________________________________ 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. 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