Microsoft Security Bulletin MS99-034 - Important
Patch Available for "Fragmented IGMP Packet" Vulnerability
Published: September 03, 1999 | Updated: March 21, 2003
Patch Availability Information Updated: March 21, 2003
Revised: September 09, 1999
Originally Posted: September 03, 1999
Microsoft has released a patch that eliminates a vulnerability in the TCP/IP stack implementations of Microsoft® Windows® 95, Windows 98® and Windows NT® 4.0. Fragmented IGMP packets can cause a variety of problems in Windows 95 and 98, up to and including causing the machine to crash. Windows NT 4.0 contains the same vulnerability, but other system mechanisms make a successful attack much more difficult.
Frequently asked questions regarding this vulnerability can be found at https://www.microsoft.com/technet/security/bulletin/fq99-034.mspx
By sending fragmented IGMP packets to a Windows 95, 98 or Windows NT 4.0 machine, it is possible to disrupt the normal operation of the machine. This vulnerability primarily affects Windows 95 and 98 machines. Depending on a variety of factors, sending such packets to a Windows 95 or 98 machine may elicit behavior ranging from slow performance to crashing.
Windows NT contains the same vulnerability, but other system mechanisms compensate and make it much more difficult to mount a successful attack.
Affected Software Versions
- Microsoft Windows 95
- Microsoft Windows 98
- Microsoft Windows 98 Second Edition
- Microsoft Windows NT Workstation 4.0
- Microsoft Windows NT Server 4.0
- Microsoft Windows NT Server 4.0, Enterprise Edition
- Microsoft Windows NT Server 4.0, Terminal Server Edition
Vulnerability Identifier: CVE-1999-0918
Windows NT Workstation 4.0; Windows NT Server 4.0; Windows NT Server, Enterprise Edition:
Windows NT Server 4.0, Terminal Server Edition:
Note The Windows 95 and 98 versions of this patch also are available via WindowsUpdate.
Please see the following references for more information related to this issue.
Microsoft Security Bulletin MS99-034: Frequently Asked Questions, https://www.microsoft.com/technet/security/bulletin/fq99-034.mspx.
Microsoft Knowledge Base (KB) article 238329, Fragmented IGMP Packets may Promote Denial of Service, </https:>https:.
Note It may take 24 hours from the original posting of this bulletin for the KB article to be visible.
Microsoft Security web site, </https:>https:.
Obtaining Support on this Issue
This is a fully supported patch. Information on contacting Microsoft Technical Support is available at </https:>https:.
- September 03, 1999: Bulletin Created.
- September 09, 1999: Revised to provide Windows 95 patch information.
- V2.0 (March 21, 2003): Introduced versioning and updated patch availability information
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