From secnotif@MICROSOFT.COM Mon Dec 21 14:16:51 1998 From: Microsoft Product Security To: MICROSOFT_SECURITY@ANNOUNCE.MICROSOFT.COM Date: Mon, 21 Dec 1998 13:05:54 -0800 Subject: Microsoft Security Bulletin (MS98-019) The following is a Security Bulletin from the Microsoft Product Security Notification Service. Please do not reply to this message, as it was sent from an unattended mailbox. ******************************** Microsoft Security Bulletin (MS98-019) -------------------------------------- Patch Available for IIS "GET" Vulnerability Originally Posted: December 21, 1998 Summary ======= Microsoft has released a patch that fixes a vulnerability in Microsoft(r) Internet Information Server(r) that could allow denial-of-service attacks to be mounted against web servers. There have been no reports of customers being affected by this vulnerability. However, Microsoft is publishing this bulletin and releasing the patch to allow customers to address the potential security risk it poses. As detailed below in What Customers Should Do, Microsoft recommends that users evaluate whether they are at risk from this attack and install the patch if appropriate. Issue ===== This vulnerability involves the HTTP GET method, which is used to obtain information from an IIS web server. Specially-malformed GET requests can create a denial of service situation that consumes all server resources, causing a server to "hang." In some cases, the server can be put back into service by stopping and restarting IIS; in others, the server may need to be rebooted. This situation cannot happen accidentally. The malformed GET requests must be deliberately constructed and sent to the server. It is important to note that this vulnerability does not allow data on the server to be compromised, nor does it allow any privileges on it to be usurped. Affected Software Versions ========================== - Microsoft Internet Information Server, versions 3.0 and 4.0, on x86 and Alpha platforms. What Microsoft is Doing ======================= On December 21, Microsoft released a patch that fixes the problem. This patch is available for download from the sites listed below. Please see What Customers Should Do for additional information on the patch. Microsoft has sent this security bulletin to customers subscribing to the Microsoft Product Security Notification Service (see http://www.microsoft.com/security/services/bulletin.asp for more information about this free customer service). Microsoft has published the following Knowledge Base (KB) article on this issue: - Microsoft Knowledge Base (KB) article Q192296, IIS: Patch Available for IIS "GET" Vulnerability, http://support.microsoft.com/support/kb/articles/q192/2/96.asp. (Note: It might take 24 hours from the original posting of this bulletin for the updated KB article to be visible in the Web-based Knowledge Base.) Microsoft has released the following hot fixes: - Fix for IIS 3.0 on X86 platforms: ftp://ftp.microsoft.com/bussys/iis/iis-public /fixes/usa/security/Infget-fix/infget3i.exe - Fix for IIS 4.0 on X86 platforms: ftp://ftp.microsoft.com/bussys/iis/iis-public /fixes/usa/security/Infget-fix/infget4i.exe - Fix for IIS 3.0 on Alpha platforms: ftp://ftp.microsoft.com/bussys/iis/iis-public /fixes/usa/security/Infget-fix/infget3a.exe - Fix for IIS 4.0 on Alpha platforms: ftp://ftp.microsoft.com/bussys/iis/iis-public /fixes/usa/security/Infget-fix/infget4a.exe (Note: the URLs above have been wrapped for readability) What Customers Should Do ======================== The patch for this vulnerability is fully supported. However, it has not been fully regression tested and should only be applied to systems determined to be at risk of attack. A fully regression-tested version of the patch will be available as part of the next Windows NT service pack. Microsoft recommends that customers evaluate the degree of risk that this vulnerability poses to their systems, based on physical accessibility, network and Internet connectivity, and other factors, and determine whether the appropriate course of action is to apply the patch or wait for the next service pack. More Information ================ Please see the following references for more information related to this issue. - Microsoft Security Bulletin 98-019, Patch Available for IIS "GET" Vulnerability (the Web-posted version of this bulletin), http://www.microsoft.com/security/bulletins/ms98-019.asp. - Microsoft Knowledge Base (KB) article Q192296, IIS: Patch Available for IIS "GET" Vulnerability, http://support.microsoft.com/support/kb/articles/q192/2/96.asp. (Note: It might take 24 hours from the original posting of this bulletin for the updated KB article to be visible in the Web-based Knowledge Base.) Obtaining Support on this Issue =============================== This is a supported patch. If you have problems installing this patch or require technical assistance with this patch, please contact Microsoft Technical Support. For information on contacting Microsoft Technical Support, please see http://support.microsoft.com/support/contact/default.asp. Acknowledgements ================ Microsoft wishes to acknowledge the contribution made by Brian Steele of Cable and Wireless Grenada, Ltd. (www.candw.com), and Eugene Kalinin of the N. N.Burdenko Neurosurgery Institute, who reported the problem to us. Revisions ========= - December 21, 1998: Bulletin Created For additional security-related information about Microsoft products, please visit http://www.microsoft.com/security --------------------------------------------------------------------------- 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. (c) 1998 Microsoft Corporation. All rights reserved. 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