KPMG-2002011: Windows 2000 microsoft-ds Denial of Service

[Peter Gründl <pgrundl () kpmg dk>]

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          -=>Windows 2000 microsoft-ds Denial of Service<=-
                      courtesy of KPMG Denmark

BUG-ID: 2002011
Released: 17th Apr 2002
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Problem:
========
The default LANMAN registry settings on Windows 2000 could allow a
malicious user, with access to TCP port 445 on your Windows 2000, to
cause a Denial of Service.


Vulnerable:
===========
- Windows 2000 Server (SP0, SP1, SP2)
- Windows 2000 Advanced Server (SP0, SP1, SP2)
- Windows 2000 Professional (SP0, SP1, SP2)


Details:
========
Sending malformed packets to the microsoft-ds port (TCP 445) can
result in kernel ressources being allocated by the LANMAN service.
The consequences of such an attack could vary from the Windows
2000 host completely ignoring the attack to a blue screen.

An attack could be something as simple as sending a continuous
stream of 10k null chars to TCP port 445.

The most common symptoms would be that the LANMAN service would
allocate a lot of kernel memory, until a point, where very few
applications would be able to run. The routine that draws windows
would commence to draw incomplete windows, the warning "beep"
would be replaced by an error stating that the sound driver could
not be loaded. Internet Information Server would no longer be
able to service .asp pages, attempts to reboot the server (as
administrator) would result in the error "You do not have
permissions to shutdown or restart this computer.", aso.

It would frequently be possible to cause the system service
to enter a state where it constantly used 100% CPU usage.
A PC was left in this state over the weekend, to see if it
would recover on it's own. It did not recover.


Vendor URL:
===========
You can visit the vendors webpage here: http://www.microsoft.com


Vendor response:
================
The vendor was contacted mid-October, 2001. The vendor released a
Q-article, describing the problem and possible solutions on the 11th
of April, 2002. KPMG was notified of the publication on the 17th of
April, 2002.


Corrective action:
==================
The vendor has suggested two possible solutions, available here:
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q320751


Author: Peter Gründl (pgrundl () kpmg dk)

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