From: Wes Johns (wesleyjmicrosoft.com)
Date: Fri May 06 2005 - 12:06:37 CDT

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The client states how it can connect and then the least common
denominator is used. By turning smb signing off you are also open to
session hijacking. So one could steal your session to a file server and
access files using your account.

Thank You
Wesley Johns MCSE:Security, CEH, CISSP, ISSAP
Microsoft Consulting Services
Phone 214-458-5551
Email: Wesleyjmicrosoft.com
IM: Wesley_johnshotmail.com

-----Original Message-----
From: Free, Bob [mailto:RWF4pge.com]
Sent: Thursday, May 05, 2005 10:51 AM
To: focus-mssecurityfocus.com
Cc: Murad Talukdar
Subject: RE: To disable SMB packet and secure channel signing
enforcement on Windows Server 2003-based domain controllers

> how does it 'decide' when it should communicate insecurely

 Murad-

In his own inimitable way Mark Minasi had a very nice little write-up on
this very subject in his mid-April newsletter(#46) he entitled "How SMB
Signing Works: An "Alcoholics Anonymous" Protocol"
You could sign up to see the archive at
http://www.minasi.com/archive.htm
I found it to be an intriguing presentation of the subject so I saved so
I saved that portion off as a separate doc. I'll send you a copy.

-----Original Message-----
From: Murad Talukdar [mailto:talukdar_msubway.com]
Sent: Wednesday, May 04, 2005 8:26 PM
To: '?????? ??????'
Cc: focus-mssecurityfocus.com
Subject: RE: To disable SMB packet and secure channel signing
enforcement on Windows Server 2003-based domain controllers

Excellent. This is now working according to Laura's/????? ?????
settings.
Thanks to everyone. I've learnt a lot from this single issue.
One last question, with the whenever possible option. According to ?????
?????, the DCs will now communicate insecurely with my printer, but does
this mean it would communicate insecurely with some 'unknown' machine
too.
What I'm trying to work out, I guess, is how does it 'decide' when it
should
communicate insecurely--what test does it carry out? Is it treating the
scanner as a member server or a client?
As the whole worry here is MITM's --are there ones which could be
utilized
now that I have set the network server to digitally sign always but the
clients and the members to do it whenever possible?
I'm thinking the risk is greatly reduced but is it removed 'completely'?

Murad
-----Original Message-----
From: ?????? ?????? [mailto:morsineastbridge.tula.ru]
Sent: Wednesday, May 04, 2005 10:52 PM
To: Murad Talukdar
Subject: Re: To disable SMB packet and secure channel signing
enforcement on
Windows Server 2003-based domain controllers

----- Original Message -----
> 1. From Administrative Tools open Domain Controller Security Policy 2.

> Smile
> 3. Select \Security Settings\Local Policies\Security Options folder.
4. In
> the details pane, double-click Microsoft network server: Digitally
sign
> communications (always), and then click Disabled to prevent SMB packet
> signing from being required. 5. Click OK. 6. In the details pane,
> double-click Domain member: Digitally encrypt or sign secure channel
data
> (always), and then click Disabled to prevent secure channel signing
from
> being required. 7. Click OK.

1. Return back to "Enabled" secure channel ecnryption requirement. SMB
file
sharing has nothing to do woth it. Secure Channel is used by domain
member
computers to pass user authentication information to DCs.
2. There are companion settings "Digitally sign communications (always)"
and

"Digitally sign communications (when possible)" for both servers and
workstations. Set first to "Disabled" and second to "Enabled" and your
DCs
will communicate securely with users and insecurely with your printer.

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