NT Subject to DoS - 27 Sep 1999

Windows NT Subject to DoS

Reported December 9, 1999 by
  • Windows NT Workstation 4.0
  • Windows NT Server 4.0
  • Windows NT Server 4.0, Enterprise Edition
  • Windows NT Server 4.0, Terminal Server Edition


When a specific type of malformed argument is supplied to a resource
enumeration request, the Windows NT Service Control Manager can fail. The primary effect of the failure is to cause named pipes to fail, which prevents many other system services from operating. The failure would not cause the machine to crash, and as a result it might not be obvious to the operator that the machine was no longer in service. An affected computer can be put back into service by rebooting.

The resource enumeration request involved in the vulnerability must be made via IPC, so customers can protect against remote attacks by blocking NetBios requests at the firewall. Networks that allow anonymous logons can prevent attacks by disabling the ability for null sessions to submit enumeration requests; this can be done using the RestictAnonymous registry key. Both of these measures are good security practices in any case.


Microsoft has released a patch for Intel and Alpha that corrects the problem, as well as a FAQ and Support Online article Q143474.

Discovered by
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