__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Windows NT, Two Denial-of-Service Vulnerabilities (Malformed LSA Request and CSRSS Worker Thread Exhaustion) June 23, 1999 17:00 GMT Number J-049 ______________________________________________________________________________ PROBLEM: Two vulnerabilities have been identified by Microsoft in Windows NT. 1) A malformed request to the Local Security Authority (LSA) service causes the service to stop responding. 2) CSRSS.EXE worker thread exhaustion can cause a denial of service. PLATFORM: Windows NT 4.0, workstation and server. DAMAGE: These vulnerabilities could allow denial of service attacks. SOLUTION: Apply available patches from Microsoft. ______________________________________________________________________________ VULNERABILITY Risk is low. Systems running these services could suffer a ASSESSMENT: denial of service but no damage results. Rebooting the system clears the denial of service. ______________________________________________________________________________ [ Start Microsoft Advisory ] 1) "Malformed LSA Request" Vulnerability Microsoft Security Bulletin (MS99-020) - -------------------------------------- Patch Available for "Malformed LSA Request" Vulnerability Originally Posted: June 23, 1999 Summary ======= Microsoft has released a patch that eliminates a vulnerability that poses a denial of service threat to Microsoft(r) Windows NT(r) servers and workstations. A malformed request to the Local Security Authority (LSA) service will causes the service to stop responding, requiring the computer to be restarted. A fully supported patch is available to eliminate the vulnerability, and Microsoft recommends that affected customers download and install it, if appropriate. Issue ===== Windows NT provides the ability to manage user privileges programmatically via the Local Security Authority (LSA) API. The API allows a program to query user names, modify privileges, and change other elements of the security policy, subject to the program's authorizations. Certain API methods do not correctly handle certain types of invalid arguments. The vulnerability is a denial of service threat only, and service can be restored by restarting the machine. There is no capability to use this vulnerability to obtain unauthorized services from LSA. While there are no reports of customers being adversely affected by this vulnerability, Microsoft is proactively releasing this patch to allow customers to take appropriate action to protect themselves against it. Affected Software Versions ========================== - Microsoft Windows NT 4.0 Workstation - Microsoft Windows NT 4.0 Server - Microsoft Windows NT 4.0 Server, Terminal Server Edition, 4.0 What Microsoft is Doing ======================= Microsoft has released patches that fix the problem identified. The patches are available for download from the sites listed below in What Customers Should Do. Microsoft also 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 Q231457, Malformed Request Causes LSA Service to Hang, http://support.microsoft.com/support/kb/articles/q231/4/57.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.) What Customers Should Do ======================== Microsoft has released patches that fix the problem identified. Microsoft highly recommends that customers evaluate the degree of risk that this vulnerability poses to their systems and determine whether to download and install the patch. The patch can be found at: - ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa /NT40/hotfixes-postSP5/LSA3-fix/ NOTE: The above URL has been word-wrapped for readability More Information ================ Please see the following references for more information related to this issue. - Microsoft Knowledge Base (KB) article Q231457, Malformed Request Causes LSA Service to Hang, http://support.microsoft.com/support/kb/articles/q231/4/57.asp. Obtaining Support on this Issue =============================== If you require technical assistance with this issue, please contact Microsoft Technical Support. For information on contacting Microsoft Technical Support, please see http://support.microsoft.com/support/contact/default.asp. Acknowledgments =============== Microsoft acknowledges BindView Corporation (http://www.bindview.com) for discovering the vulnerability and reporting it to us. Revisions ========= - June 23, 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. For security-related information about Microsoft products, please visit the Microsoft Security Advisor web site at http://www.microsoft.com/security. 2) "CSRSS Worker Thread Exhaustion" Vulnerability Microsoft Security Bulletin (MS99-021) - -------------------------------------- Patch Available for "CSRSS Worker Thread Exhaustion" Vulnerability Originally Posted: June 23, 1999 Summary ======= Microsoft has released a patch that eliminates a vulnerability in the Microsoft(r) Windows NT(r) CSRSS process that could be used to create a denial of service condition against a machine that allows interactive logons. Frequently asked questions regarding this vulnerability, its background, and the patch can be found at http://www.microsoft.com/security/bulletins/ms99-021faq.asp Issue ===== If all worker threads in CSRSS.EXE are occupied awaiting user input, no other requests can be serviced, effectively causing the server to hang. When user input is provided, processing returns to normal. The patch eliminates the vulnerability by ensuring that the last CSRSS worker thread services only requests that do not require user input. Affected Software Versions ========================== - Microsoft Windows NT 4.0 Workstation - Microsoft Windows NT 4.0 Server - Microsoft Windows NT 4.0 Server, Enterprise Edition Patch Availability ================== The patch is available at ftp://ftp.microsoft.com/bussys/winnt/ winnt-public/fixes/usa/nt40/Hotfixes-PostSP5/CSRSS-fix/ NOTE: A line break has been inserted into the above URL for readability. More Information ================ Please see the following references for more information related to this issue. - Microsoft Security Bulletin MS99-021: Frequently Asked Questions, http://support.microsoft.com/support/bulletins/ms99-021faq.asp. - Microsoft Knowledge Base (KB) article Q2133323, "Exceeding MaxRequestThreads may Cause Windows NT to Hang", http://support.microsoft.com/support/kb/articles/q231/3/23.asp. (Note: It may take 24 hours from the original posting of this bulletin for the KB article to be visible.) - Microsoft Security Advisor web site, http://www.microsoft.com/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 acknowledges Jeff Sumner for discovering this vulnerability and reporting it. Revisions ========= - June 23, 1999: 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. (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. For security-related information about Microsoft products, please visit the Microsoft Security Advisor web site at http://www.microsoft.com/security. [ End Microsoft Advisory ] ______________________________________________________________________________ CIAC wishes to acknowledge Microsoft Corp. 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. 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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. LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC) J-039: HP-UX Vulnerabilities (MC/ServiceGuard & MC/LockManager, DES J-040: HP-UX Security Vulnerability in sendmail J-041: Cisco IOS(R) Software Input Access List Leakage with NAT J-042: Web Security J-043: (bulletin in process) J-044: Tru64/Digital UNIX (dtlogin) Security Vulnerability J-045: Vulnerability in statd exposes vulnerability in automountd J-046: HP-UX VVOS NES Vulnerability J-047: The ExploreZip Worm J-048: Malformed HTR Request Vulnerability -----BEGIN PGP SIGNATURE----- Version: 4.0 Business Edition iQCVAwUBN3KgG7nzJzdsy3QZAQFI+gQA2rUvAyiUfWxYw6O0VQB7uE+Xv7B1b6Uv u5Vo7ufBviqnkYBGBfqulK41vwdH+HTYBe4//23Z0t26xYm6aUtogm+KP7HoMi7m KIGPvOwPZI+qUB8eon6U9E8HFtQmJpO2pkOWD+oxyrKoRlbYZ1Kmz2lc3Ii8q9/5 RuxG7DrxGrk= =OrDc -----END PGP SIGNATURE-----