OSEC

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Subject: Re: Windows 2000 Nul bug
From: leventHUSHMAIL.COM
Date: Sat Apr 29 2000 - 11:55:15 CDT

I'm not sure why this is perceived as a security bug. It is a file association
issue. If it allows you to bypass the security of policies regarding application
launches or the ntfs file security associated with the files, then yes it
is a security bug. Otherwise, the only thing this does is to show you the
applications installed on the machine. Since file associations will allow
you to glean the same info I don't see a problem. I'll agree that you shouldn't
be able to see those applications unless you have file or registry security
associated with same. My guess is that the dialog is pulling it from file
associations out of the registry.

I see the issue on Windows 2000 build 2195. You can also initiate by doing
something like starting a program with an unknown association.

levent

-----Original Message-----
From: Mousse [mailto:mousseCROSSWINDS.NET]
Sent: Saturday, April 29, 2000 11:45 AM
To: win2ksecadviceLISTSERV.NTSECURITY.NET
Subject: Re: Windows 2000 Nul bug

Apparently, Microsoft's already patched the problem.
On Windows 2000 Professional v. 5.00.2195 (Standard OEM),
neither the "nul" nor the "other" backdoors seem to work. The
similar goes for the latest Windows 2000 Server (also Standard
OEM) release.

~Mousse

> -----Original Message-----
> From: auto45040HUSHMAIL.COM [mailto:auto45040HUSHMAIL.COM]
> Sent: Saturday, April 29, 2000 12:04 AM
> To: win2ksecadviceLISTSERV.NTSECURITY.NET
> Subject: Windows 2000 Nul bug
>
>
> <-[DHC ADVISORY]->
>
> Title: Nul security AND D.O.S problem for Windows 2000
> Description program: Well I guess we all know what Windows 2000 is. :)
> Description problem: Simply by typing "nul" in a dos prompt, you
> get a screen
> with all kinds of programs you can start and by hitting a button you also
> get a "open file" style explorer window.
>
> <-[what was used]->
> Windows Professional 2000 build 2128
>
> <-[how to create the security problem]->
> start up a dos prompt and type "nul" and then enter. I attached a
> file (nil.bat)
> for the people who either don't have a prompt (because of restrictions,
> or whatever) or just don't know how to do it.
> You'll get a little screen with a list of programs to open "nul.pif" with.
> Just choose what you want to start up. Anything that is on your computer
> is now available.
> More dangerous maybe is the possibility to hit "other" and you're able
to
> browse the drives and directories. Funny thing is that with windows NT
by
> typing the drive name in the file name bit you can even access hidden
but
> shared drives, so I figure this'll still work with Windows 2000 too, but
> at the moment I'm not sure.
> To be honest, the same can be achieved by double-clicking an
> undefined fileformat.
> However, a lot of administrators will have found a way to stop this, so
> basically this is a workaround for that.
>
> <-[fix]->
> Well, I expect Microsoft will have a fix for the security problem, so
I
> won't bother with that.
>
> <-[note]->
> credit where credit is due: I wouldn't've gone and checked "nul" out in
> W2k if it weren't for someone posting to Bugtraq saying c:\nul\nul like
> c:\con\con could lock up W98. I was being curious.
>
> Greetz,
> nemesystm, leader of the DHC (dhcorp.cjb.net)
> auto45040hushmail.com
> - 1 found 62999 to go -

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