RE: Exploit through firewall question

From: Bob.Maggard@sanofi-aventis.com
Date: Wed Jul 19 2006 - 12:58:56 EDT


Depending upon your architecture your DMZ may be shared by several
servers. In this case an attack can come from another DMZ server that
has been compromised (Perhaps from the Internet) or an internal host. If
you perform the VA from behind the firewall you will end up mitigating
these attack vector to a better degree.

Firewalls only do what people configure them to do. If some one
accidentally opens a rule (Say for port 21) but accidentally open the
port up for all DMZ servers. Hardening the services for all listening
ports will give you another layer of protection.

It is a good idea to do the VA before you expose a server to the
Internet. This is another good reason for doing a VA behind the
firewall. Once you are done with the resultant hardening you are ready
to connect it to the Internet via your firewall. You can then do a port
scan from the Internet as a last step to confirm that the ports you
expected to be open are the only ones that are open.

-----Original Message-----
From: mr.nasty@ix.netcom.com [mailto:mr.nasty@ix.netcom.com]
Sent: Wednesday, July 19, 2006 8:33 AM
To: pen-test@securityfocus.com
Subject: Re: Exploit through firewall question

Thanks for the responses. You've confirmed what I had passed to mgmt.
But I still have a problem (with mgmt) understanding why?...

I perform vulnerability analysis on our outside (public) web presense,
usually during development and then after it's been deployed. I
basically use the same tools for each.

Mgmt wants me to only test through the firewall as if I'm coming in like
the public. The rational is that the fw will prevent any attacks though
ports other than 80 and 443. Therefore, there is no reason to change
this configuration.

What would be the reason to test behind the firewall?

Any suggestions?

Thanks

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This List Sponsored by: Cenzic

Concerned about Web Application Security?
Why not go with the #1 solution - Cenzic, the only one to win the Analyst's
Choice Award from eWeek. As attacks through web applications continue to rise,
you need to proactively protect your applications from hackers. Cenzic has the
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