Microsoft Security Bulletin (MS99-028)
Patch Available for "Terminal Server Connection Request Flooding" Vulnerability
Patch Availability Information Updated: March 21, 2003
Originally Posted: August 09, 1999
Summary
Microsoft has released a patch that eliminates a vulnerability that could pose a denial-of-service threat to Microsoft® Windows NT® Terminal Servers. Frequently asked questions regarding this vulnerability can be found at http://www.microsoft.com/technet/security/bulletin/fq99-028.mspx
Issue
When a request to open a new terminal connection is received by a Terminal Server, the server undertakes a resource-intensive series of operations to prepare for the connection. It does this before authenticating the request. This would allow an attacker to mount a denial of service attack by levying a large number of bogus connection requests and consuming all memory on the Terminal Server.
This vulnerability could be exploited remotely if connection requests are not filtered. In extreme cases, the server could crash in the face of such an attack; in other cases, normal processing would return when the attack ceased. The patch works by causing the server to require authentication before processing the connection request.
Affected Software Versions
| • | Microsoft Windows NT Server 4.0, Terminal Server Edition |
Vulnerability Identifier: CVE-1999-0680
Patch Availability
| • | Microsoft Windows NT Server 4.0, Terminal Server Edition: http://www.microsoft.com/technet/security/patchavailability.mspx |
More Information
Please see the following references for more information related to this issue.
| • | Microsoft Security Bulletin MS99-028: Frequently Asked Questions, http://www.microsoft.com/technet/security/bulletin/fq99-028.mspx. |
| • | Microsoft Knowledge Base (KB) article 238600, Multiple Connection Requests Promote Denial of Service Attack, http://support.microsoft.com/default.aspx?scid=kb;en-us;238600&sd=tech. Note It may take 24 hours from the original posting of this bulletin for the KB article to be visible. |
| • | Microsoft Security web site, http://www.microsoft.com//technet/security/default.mspx. |
Obtaining Support on this Issue
This is a fully supported patch. Information on contacting Microsoft Technical Support is available at http://support.microsoft.com/contactussupport/?ws=support.
Acknowledgments
Microsoft acknowledges the ISS X-force for discovering this vulnerability and working with us to alert customers about it.
Revisions
| • | August 09, 1999: Bulletin Created. |
| • | V2.0 (March 21, 2003): Introduced versioning and updated patch availability information. |
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