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RE: DMZ and AD Authentication
From: jamesworld () intelligencia com
Date: Wed, 17 Dec 2003 11:39:09 -0600

Roger,

Having dealt with a compromised web server in a DMZ that was allowing all things to happen as they were (nothing obviously wrong). It was found to have a sniffer that was grabbing transaction data. It was also grabbing the communication through the dmz to the internal hosts. IPSEC would have made that futile. I configured it to IPSEC VPN to the firewall and then dump the clear traffic out on the internal network where the NIDS could watch it for funny stuff.

That in combination with the Cisco Security Agent (former Okena) protects and makes it pretty much bulletproof. Obviously the CSA must be tuned properly for that level of assurance though.

-James

At 15:06 12/16/2003, Rademacher Sgt Roger P wrote:
Hi,
I have a similar config being setup in my environment.
We have an Apache server in the DMZ that is reverse proxying two
connection inside to an oracle WebCache server (www and login).  The
WebCache server splits the request based on url and forwards to the
appropriate server.
The firewall allows external access to the DMZ machine and from the dmz
machine to the internal WebCache server all on https/443.  If the
reverse proxy is compromised they can see the internal WebCache server
but not the LDAP being stored on the login server.  Both the reverse
proxy and the WebCache server would need to be compromised for the LDAP
to be accessed directly.
Is this a viable option or should I fight for another communication
setup such as an IPSec connection from the DMZ machine inside to the
WebCache server?
Rog

-----Original Message-----
From: jamesworld () intelligencia com [mailto:jamesworld () intelligencia com]
Sent: Monday, December 15, 2003 9:57 PM
To: Geoff.Shatz () pchelps com
Cc: security-basics () securityfocus com
Subject: RE: DMZ and AD Authentication


Geoff,

I second what Shawn said.  If you can avoid it...don't do it.

If however, you are stuck with an order from up high.

Connect to the AD box thru the firewall via IPSEC.

If you use NIDS, however, this will blind it to any attack's that might
come thru is the web server was compromised.

I would recommend using the Cisco Security Agent (formerly Okena) on the

web server.

The other thing you could do is use a Cisco ACS server to front end the
AD
authentication and have the web server authenticate to the ACS via
RADIUS
or TACACS.  You will need to code the RADIUS integration (unless you can

find it somewhere :-)

HTH,

-James

At 11:25 12/12/2003, Shawn Jackson wrote:

>         All you need LDAP access (TCP 389) to your Catalogue server.
>Even if you lock down your connection to the AD box, if someone
>compromises your IIS server they can gain a lot of information from
your
>server. When we used this method with C# .Net we needed to have LDAP
and
>Microsoft-DS (TCP 445) open to the server.
>
>         Honestly, I would advise against placing a server in the DMZ
>that will access any part of your AD infrastructure; it's just not
>secure enough. If you absolutely had to authenticate with AD I'd
suggest
>creating a simple program (Webpage (ASP, CGI, and CF) or .Net
>Service/Remote App that would take two parameters (Username and
>Password) and return a value, then just parse that value to get your
>logon result. Place that app on a 'non-critical' server and it will be
>far more secure then accessing AD directly.
>
>         I can give you the code I use to access AD in C# and suggested
>implementation if you wish.
>
>Shawn Jackson
>Systems Administrator
>Horizon USA
>1190 Trademark Dr #107
>Reno NV 89521
>www.horizonusa.com
>
>Email: sjackson () horizonusa com
>Phone: (775) 858-2338
>        (800) 325-1199 x338
>
>-----Original Message-----
>From: Geoff.Shatz () pchelps com [mailto:Geoff.Shatz () pchelps com]
>Sent: Friday, December 12, 2003 7:33 AM
>To: security-basics () securityfocus com
>Subject: DMZ and AD Authentication
>
>We are in a situation where we are currently planning the move of our
>web server from an externally hosted solution to hosting the web server
>in house. As part of this move we will be implementing a new internal
>application that will run on the web server that will require
>authentication based on Active Directory account info. Obviously this
>will require that the web server has the ability to communicate with
the
>AD domain controllers. That being the case will it still be possible to
>place this web server on a DMZ or will the amount of open ports
required
>between the DMZ and LAN for the required authentication process
severely
>mitigate the benefits of placing the server in the DMZ in the first
>place? Any and all suggestions and or strategies to accomplish this in
>the most secure fashion are welcome and appreciated. Thanks!
>
>Geoff
>
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