DOCUMENT:Q154174 [crossnet] TITLE :Invalid ICMP Datagram Fragments Hang Windows NT, Windows 95 PRODUCT :Microsoft Windows NT and Windows 95 PROD/VER:3.51 4.00 OPER/SYS:WINDOWS KEYWORDS:kbbug3.51 kbbug4.00 kbfile kbfix3.51 kbfix4.00 NTSrvWkst nttcp -------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Workstation version 3.51 and 4.0 - Microsoft Windows NT Server version 3.51 and 4.0 - Microsoft Windows 95 -------------------------------------------------------------------------- SYMPTOMS ======== Computers running Windows NT or Windows 95 may stop responding (hang) when they receive corrupted Internet Control Message Protocol (ICMP) datagram fragments from a client. RESOLUTION ========== Microsoft has updated the TCP/IP protocol stack to correct this problem. Instructions for installing it are available from Microsoft support channels or directly from the Internet locations below. NOTE: This hotfix was originally posted on July 7, 1997. A subsequent fix was completed on January 9, 1998 to address another nearly identical attack and this hotfix has replaced the original one. The original hotfix is included in Windows NT 4.0 Service Pack 3. The most recent hotfix is not; however, it is available from the following Internet locations: Windows NT 4.0 -------------- NOTE: Service Pack 3 must be applied to Windows NT 4.0 prior to applying this fix. This fix should have the following time stamp: 01/09/98 08:16a 143,664 Tcpip.sys (Intel) 01/09/98 08:13a 263,536 Tcpip.sys (Alpha) This hotfix has been posted to the following Internet location: ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT40/ hotfixes-postSP3/teardrop2-fix Windows NT 3.51 --------------- NOTE: Service Pack 5 must be applied to Windows NT 3.51 prior to applying this fix. This fix should have the following time stamp: 01/14/98 12:04p 123,824 Tcpip.sys (Intel) 01/14/98 12:00p 216,848 Tcpip.sys (Alpha) This hotfix has been posted to the following Internet location: ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT351/ hotfixes-postSP5/teardrop2-fix Windows 95 ---------- This issue is resolved by the following updated file for Windows 95 and OSR2: Vip.386 version 4.0.956 (dated 6/30/97) or later This file is included in the self-extracting Vipup11.exe file. To install this update, follow these steps: 1. Download the Vipup11.exe file from the Microsoft Software Library to an empty folder. 2. In My Computer or Windows Explorer, double-click the Vipup11.exe file you downloaded in step 1. 3. Follow the instructions on the screen. The following file is available for download from the Microsoft Software Library: ~ Vipup11.exe For more information about downloading files from the Microsoft Software Library, please see the following article in the Microsoft Knowledge Base: ARTICLE-ID: Q119591 TITLE : How to Obtain Microsoft Support Files from Online Services The following files are installed by Vipup11.exe: File name Version Date/Time Size Destination folder ---------------------------------------------------------------------- Vip.386 4.00.956 6/30/97 9:54am 171,672 Windows\System STATUS ====== Microsoft has confirmed this to be a problem in Windows NT version 4.0. A supported fix is now available, but has not been fully regression tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information. Microsoft has confirmed this to be a problem in Windows NT version 3.51. A supported fix is now available, but has not been fully regression tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information. Microsoft has confirmed this to be a problem in Microsoft Windows 95 and OEM Service Release 2 (OSR2). An update to address this problem is now available, but is not fully regression tested and should be applied only to computers experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft does not recommend implementing this update at this time. Contact Microsoft Technical Support for additional information about the availability of this update. Additional query words: prodnt 4.00 3.51 win95 ssping spingnuke denial of service attack hangs ============================================================================ 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. Copyright Microsoft Corporation 1997.