Vulnerability Note VU#693099

Microsoft Windows 2000 vulnerable to DoS via malformed packets sent to port 445/tcp

Overview

The default configuration of Microsoft Windows 2000 does not properly handle malformed packets received on TCP port 445. As a result, Windows may cease to function normally upon receipt of malformed packets on this port.

I. Description

Microsoft LAN Manager (LANMAN) is enabled by default on systems running Microsoft Windows 2000. LANMAN listens to TCP port 445 and allocates kernel resources to handle requests on this port.

When LANMAN receives malformed packets, the system allocates kernel memory to handling these packets. When memory use approaches 100%, Windows and other applications may begin to behave erratically or fail. Symptoms may include: chronically incomplete drawing of windows; on-screen error boxes indicating that the sound driver could not be loaded, when a system sound would normally be played; IIS failure to execute ASP pages; and error messages such as "You do not have permissions to..." when attempting routine tasks such as restarting the system.

According to testing performed at KPMG Denmark, a system attacked by exploitation of the vulnerability may not be able to recover on its own, once memory is sufficiently consumed to inhibit normal operation.

II. Impact

The complete impact of this vulnerability is not yet known. Consumption of memory will make applications fail in various ways and disrupt services provided by the system.

III. Solution

Apply a patch

Upgrade to Windows 2000 Service Pack 3.

Systems Affected

Vendor	Status	Date Updated
Microsoft Corporation	Vulnerable	10-Aug-2002

References

http://www.securityfocus.com/bid/4532

Credit

Thanks to Peter Gr�ndl for reporting this vulnerability.

This document was written by Shawn Van Ittersum.

Other Information

Date Public	04/17/2002
Date First Published	09/16/2002 07:45:25 PM
Date Last Updated	04/15/2003
CERT Advisory
CVE Name
US-CERT Technical Alerts
Metric	5.49
Document Revision	7

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