Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2000.088 -- Microsoft Security Bulletin (MS00-031) Patch Available for "Undelimited .HTR Request" and "File Fragment Reading via .HTR" Vulnerabilities 11 May 2000 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Internet Information Server 4.0 Internet Information Server 5.0 Vendor: Microsoft Operating System: MS Windows Server Platforms Platform: N/A Impact: Denial of Service Read-only Data Access Access Required: Remote - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Microsoft Security Bulletin (MS00-031) - - -------------------------------------- Patch Available for "Undelimited .HTR Request" and "File Fragment Reading via .HTR" Vulnerabilities Originally Posted: May 10, 2000 Summary ======= Microsoft has released a patch that eliminates two security vulnerabilities in Microsoft(r) Internet Information Server. The vulnerabilities could, respectively, be used to slow an affected web server's response or to obtain the source code of certain types of files under very restricted conditions. Frequently asked questions regarding these vulnerabilities and the patch can be found at http://www.microsoft.com/technet/security/bulletin/fq00-031.asp Issue ===== This patch eliminates two security vulnerabilities that are unrelated except by virtue of the fact that both exist in the ISAPI extension that provides web-based password administration via .HTR scripts. - The "Undelimited .HTR Request" vulnerability is a denial of service vulnerability. If a malicious user provided a password change request that was missing an expected delimiter, the algorithm would conduct an unbounded search. This would prevent it from servicing additional .HTR requests, and could also slow the overall response of the server. - The ".HTR File Fragment Reading" vulnerability could allow fragments of certain types of files to be read by providing a malformed request that would cause the .HTR processing to be applied to them. However, the vulnerability could only be exploited under extremely restrictive conditions, and the most valuable data in the files would be the least likely to actually appear in the fragments sent to the user. Neither of these vulnerabilities would allow data to be added, deleted or changed on the server, nor would they allow any administrative control on the server to be usurped. Although .HTR files are used to allow web-based password administration, neither of these vulnerabilities involve any weakness in password handling. Also, if security best practices have been followed, and unneeded script mappings have been removed, many customers will have removed the .HTR script mapping and thus be unaffected by either vulnerability. Affected Software Versions ========================== - Internet Information Server 4.0 - Internet Information Server 5.0 Patch Availability ================== - Internet Information Server 4.0: http://www.microsoft.com/Downloads/Release.asp?ReleaseID=20905 - Internet Information Server 5.0: http://www.microsoft.com/Downloads/Release.asp?ReleaseID=20903 Note: Additional security patches are available at the Microsoft Download Center More Information ================ Please see the following references for more information related to this issue. - Frequently Asked Questions: Microsoft Security Bulletin MS00-031, http://www.microsoft.com/technet/security/bulletin/fq00-031.asp - Microsoft Knowledge Base article Q260838 discusses the "Undelimited .HTR Request" vulnerability and will be available soon. - Microsoft Knowledge Base article Q260069 discusses the "File Fragment Reading via .HTR" vulnerabilty and will be available soon. - How to Change Windows NT Account Passwords Using Internet Information Server (IIS) 4.0, http://www.microsoft.com/technet/support/kb.asp?ID=184619 - Microsoft TechNet Security web site, http://www.microsoft.com/technet/security/default.asp Obtaining Support on this Issue =============================== This is a fully supported patch. Information on contacting Microsoft Technical Support is available at http://support.microsoft.com/support/contact/default.asp. Acknowledgments =============== Microsoft thanks Internet Security Systems' X-force (http://xforce.iss.net/), and David Litchfield of Cerberus Information Security, Ltd (http://www.cerberus-infosec.co.uk/), for reporting these vulnerabilities to us, and working with us to protect customers. Revisions ========= - May 10, 2000: Bulletin Created. - - ------------------------------------------------------------------- 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. Last updated May 10, 2000 (c) 2000 Microsoft Corporation. All rights reserved. Terms of use. - -----BEGIN PGP SIGNATURE----- Version: PGP 6.0.2 iQEVAwUBORoSp40ZSRQxA/UrAQGDqgf+JmL//1aDXlexAbRHL3mOu1N8dclUtP2y XtB7fxhI4Xf579nR3ITbIBjJd5hfR3AlFnFA0zB5GK9PNn7HF25CAMBwE+8qo1rg liVjSbzqgQja+5mibRwcRV7ez4E4BS1HVxs8e2kxxubb705lROHRvxxo/HyPWPum QLJXgjd4Ukxorg2cCFU7rR/5cM6EnkvbRZfEjm+QgLDDYDRgoE4yerCIFYqrW9N6 RDnpHW2AmAkP7rRCn9Z6FPme9HzTAtvYyFq2e9u1G+il/EgJwjPShjqBRE9HkZfI 8Dmjfa7z41OzN/5meEOTeHg6puQB9ZingIFowxUweYgVcFAKdRfdmg== =zUkE - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- =========================================================================== This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document referenced above, AusCERT has had no control over its content. The decision to use any or all of this information is the responsibility of each user or organisation, and should be done so in accordance with site policies and procedures. If you have any questions or need further information, please contact Microsoft Corporation directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/Information/advisories.html If you believe that your system has been compromised, contact AusCERT or your representative in FIRST (Forum of Incident Response and Security Teams). Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for emergencies. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key iQCVAwUBOXXSQCh9+71yA2DNAQFQ9AQAgz8ni8dBv0HVMWvQizLz9s3fUD9RN4Je VnGydeV91TFRVA7TBqEimF+qMLXCmRvhGSoUnf2hURXvH0rekeOPwJUITPTYsjhY PmfYmd62t5D8+CWXTIlWQDE8UjvAU3kjAF7bpm0HuOenI9yJ2ejbf5hXp1YaK8Hd evgkxq4jN8w= =sWtR -----END PGP SIGNATURE-----