Invalid ICMP Datagram Fragments Hang Windows NT, Windows 95 (154174)

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

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

152734 How to Obtain the Latest Windows NT 4.0 Service Pack

For your convenience, the English version of this post-SP3 hotfix has been posted to the following Internet location. However, Microsoft recommends that you install Windows NT 4.0 Service Pack 4 to correct this problem.

ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT40/hotfixes-postSP3/teardrop2-fix

NOTE: Service Pack 3 must be applied to Windows NT 4.0 prior to applying this 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, and later versions of this file:

   Vip.386  version 4.0.958  dated 1/14/98 9:58am  66,734 bytes

This file is included in the self-extracting Vipup11.exe file.

The following file is available for download from the Microsoft Download Center:

Download Vipup11.exe now

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to Obtain Microsoft Support Files from Online Services

Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file. The following files are installed by Vipup11.exe:

   File name  Version    Date/Time        Size     Destination folder
   ------------------------------------------------------------------
   Vip.386    4.00.958   1/14/98 9:58am   66,734   Windows\System

STATUS

Microsoft has confirmed this problem could result in some degree of security vulnerability in Windows NT version 4.0. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4. Microsoft has confirmed this problem could result in some degree of security vulnerability in Windows NT version 3.51. A fully supported fix is now available, but it has not been fully regression tested and should only be applied to systems determined to be at risk of attack. Please evaluate your system's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to your system. If your system is sufficiently at risk, Microsoft recommends you apply this fix. Otherwise, wait for the next Windows NT service pack, which will contain this fix. Please 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.