From owner-csa@sprocket.nosc.MIL Sat Feb 27 14:43:10 1999 From: owner-csa@sprocket.nosc.MIL To: CSA-List@sprocket.nosc.MIL Date: Tue, 16 Feb 1999 07:09:32 -0500 Subject: IAVA 1999-0004 Microsoft IIS "Malformed FTP List Request" Vulnerability Sender: owner-csa Precedence: bulk Automated Systems Security Incident Support Team (ASSIST) Advisory 1999-0004 Release date: 11 Feb 1999 TOPIC: Microsoft IIS "Malformed FTP List Request" Vulnerability DESCRIPTION: Microsoft's IIS FTP server has a vulnerability that is remotely executable. This vulnerability is due to a programming flaw that allows an intruder to execute arbitrary code on a remote system. PLATFORM: Microsoft Operating systems with IIS version 3 & 4 installed IMPACT: An intruder could gain unrestricted access to a system as a result of this vulnerability. While Microsoft lists this vulnerability as primarily a denial of service attack, ASSIST believes the attack could likely result in unauthorized access based on past exploits. SOLUTION: Apply the patches as described in the attached bulletin -------------------- Attached Bulletin ------------------- Microsoft Security Bulletin (MS99-003) -------------------------------------- Patch Available for IIS "Malformed FTP List Request" Vulnerability Originally Posted: February 3, 1999 Summary ======= Microsoft has released a patch that eliminates a vulnerability in the Internet Information Server (r) FTP service. This vulnerability could allow denial of service attacks against the server or, under certain conditions, could allow arbitrary code to be executed on the server. A fully supported fix for this problem is available. As detailed below in What Customers Should Do, Microsoft recommends that customers who are at risk from this vulnerability apply the patch. Issue ===== The FTP service in IIS has an unchecked buffer in a component that processes "list" commands. This results in a vulnerability that poses two threats to safe operation. The first is a denial of service threat; a malformed "list" request could overflow the buffer causing the server to crash. The second is more esoteric and would be far more difficult to exploit. A carefully-constructed "list" request could cause arbitrary code to execute on the server via a classic buffer overrun technique. Neither variant could be exploited accidentally. It is noteworthy that the "list" command is only available to users after they have authenticated to the server. As a result, only users who are authorized to use the server would be able to mount such an attack, and their presence on the server could be logged if the owner of the site chose to do so. However, many sites provide guest accounts, and this could allow a malicious user to attack the server anonymously. Microsoft has no reports of any customers being affected by this vulnerability. However, Microsoft is proactively releasing a patch that corrects the problem. Affected Software Versions ========================== The following software versions are affected: - Microsoft Internet Information Server 3.0 and 4.0 What Microsoft is Doing ======================= On February 3rd, Microsoft released a patch that fixes the problem identified above. This patch is available for download from the sites listed below. 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 Q188348, Specially-Malformed FTP Requests Can Create Denial of Service http://support.microsoft.com/support/kb/articles/q188/3/48.asp (Note: It might take 24 hours from the original posting of this bulletin for the KB article to be visible in the Web-based Knowledge Base.) Microsoft has posted hot fixes to address this problem. Please note that all of these patches are designed to be applied atop Windows NT (r) 4.0 SP4. The URLs below have been word-wrapped for readability. - Fix for X86 version of IIS 3.0: ftp://ftp.microsoft.com/bussys/iis/iis-public/ fixes/usa/security/ftpls-fix/ftpls3i.exe - Fix for Alpha version of IIS 3.0: ftp://ftp.microsoft.com/bussys/iis/iis-public/ fixes/usa/security/ftpls-fix/ftpls3a.exe - Fix for X86 version of IIS 4.0: ftp://ftp.microsoft.com/bussys/iis/iis-public/ fixes/usa/security/ftpls-fix/ftpls4i.exe - Fix for Alpha version of IIS 4.0: ftp://ftp.microsoft.com/bussys/iis/iis-public/ fixes/usa/security/ftpls-fix/ftpls4a.exe What customers should do ======================== Microsoft highly recommends that all affected customers download the patch to protect their computers. The complete URL for each affected software version is provided above in What Microsoft is Doing. More Information ================ Please see the following references for more information related to this issue. - Microsoft Security Bulletin MS99-003, Patch Available for IIS "Malformed FTP List Request" Vulnerability (the Web-posted version of this bulletin), http://www.microsoft.com/security/bulletins/ms99-003.asp. - Microsoft Knowledge Base (KB) article Q188348, Specially-Malformed FTP Requests Can Create Denial of Service, http://support.microsoft.com/support/kb/articles/q188/3/48.asp (Note: It might take 24 hours from the original posting of this bulletin for the KB article to be visible in the Web-based Knowledge Base.) Acknowledgements ================ Microsoft wishes to acknowledge the eEye Digital Security Team for discovering this vulnerability. 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. Revisions ========= - February 3, 1999: 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) 1999 Microsoft Corporation. All rights reserved. Terms of Use. ******************************************************************* You have received this e-mail bulletin as a result of your registration to the Microsoft Product Security Notification Service. You may unsubscribe from this e-mail notification service at any time by sending an e-mail to MICROSOFT_SECURITY-SIGNOFF-REQUEST@ANNOUNCE.MICROSOFT.COM The subject line and message body are not used in processing the request, and can be anything you like. For more information on the Microsoft Security Notification Service please visit http://www.microsoft.com/security/bulletin.htm. 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