NetBIOS Name Server Protocol Spoofing

A specific type of NetBIOS packet can be sent to a machine to cause that machine to relenquish its name. In such instances, user attempts to access that machine via its name would fail.

ITPro Today

July 26, 2000

1 Min Read
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Reported July 27, 2000 by PGP Security and Sir Dystic of cDc

VERSIONS AFFECTED

  • Microsoft Windows NT 4.0 Workstation

  • Microsoft Windows NT 4.0 Server

  • Microsoft Windows NT 4.0 Server, Enterprise Edition

  • Microsoft Windows NT 4.0 Server, Terminal Server Edition

  • Microsoft Windows 2000

DESCRIPTION

By sending a specifically designed NetBIOS packet tosusceptible Windows machines,those machine can be made to relinquish their names or fail to successfully register theirnames on the network. Such an attack would render the machine unavailable to users thatattempt access via the machine's NetBIOS name.

VENDOR RESPONSE

Microsoft issued a FAQ,a Support Online article Q269239,and a patch for Windows 2000 to correct the problem. According toMicrosoft's bulletin, patches will be available "shortly" for NT 4.0 seriesoperating system, although no explanation for the delay was given.

User are urged to filter NetBIOS traffic(TCP 137, 138 and UDP 139) in order to prevent disruptions

CREDIT
Discovered by PGP Security and Sir Dystic of cDc

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