Denial of Service in Applications Using RPC over Named Pipes

This article was previously published under Q195733
This article has been archived. It is offered "as is" and will no longer be updated.
SYMPTOMS
Your Windows NT computer's responsiveness appears sluggish, and networkclients may report a gradual decrease in system performance because of aWindows NT system process consuming 100 percent of CPU time. In addition,system memory usage may continually increase (potentially indicating amemory leak of system resources) up to the limit of available memory. Thecomputer may stop responding (hang).
CAUSE
This problem is caused by a malicious attack on the remote procedure call(RPC) components in Windows NT using named pipes transport. Specificinstances of this denial of service attack may be targeted at either theSpoolss.exe file or Lsass.exe file. There are different variations of theattack and each may create multiple named pipe connections to a Windows NTsystem and send random data. The RPC service then attempts to send aresponse and close each connection. The RPC service then cycles into a 100percent CPU usage loop closing the invalid connections.
RESOLUTION

Windows NT Server and Workstation, Windows NT Server, Enterprise Edition

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to:
For information on obtaining the individual software update, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

Windows NT Server 4.0, Terminal Server Edition

To resolve this problem, obtain the latest service pack for Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in theMicrosoft Knowledge Base:
152734 How to Obtain the Latest Windows NT 4.0 Service Pack

STATUS

Windows NT Server and Workstation, Windows NT Server, Enterprise Edition

Microsoft has confirmed this problem could result in some degree ofsecurity vulnerability in Windows NT version 4.0. This problem was first corrected in Windows NT version 4.0 Service Pack 5.

Windows NT Server 4.0, Terminal Server Edition

Microsoft has confirmed this problem could result in some degree ofsecurity vulnerability in Windows NT version 4.0, Terminal Server Edition.Microsoft has confirmed that this is a problem in Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT Server 4.0, Terminal Server Edition Service Pack 4.
MORE INFORMATION
Using Windows NT Performance Monitor, you observe that, over time, thecomputer's CPU usage increases to 100 percent and remains there.
denial of service nprpcfix
Properties

Article ID: 195733 - Last Review: 02/21/2014 00:30:51 - Revision: 4.0

  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 4.0 Standard Edition
  • Microsoft Windows NT Server 4.0 Enterprise Edition
  • Microsoft BackOffice Small Business Server 4.0
  • kbnosurvey kbarchive kbHotfixServer kbqfe kbbug kbfix KB195733
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