Re: Clueless firewall configuration ?

[John Kinsella <jlk () thrashyour com>]

Gotta second Chris' third point.  I've watched many network engineers
eyes glass over as I try to explain to them that it's not just a core
router, it's not just a distro switch, nor is it a firewall.  The
passing score to be able to survive on one of these setups takes someone
who has a very firm grip on what they're doing.

Another thought I don't think has been mentioned yet - you've got
possibly several hundred ports terminating on these beasts, but a pretty
limited number of span ports.  This puts constraints on your ability to
"drop" an IDS on a VLAN without adding network taps or other tricks.
Just something to keep in mind...

John

On Sat, Aug 12, 2006 at 08:55:42AM -0500, Chris Byrd wrote:
> A few problems I see with this:
>
> 1. Having untrusted traffic on your core switch can cause the
> potential for a remote DoS attack against your core.  Switches have
> been known to keel over under certain circumstances (the Slammer worm
> was one) where there are lots of small packets on the wire.
>
> 2. VLAN hopping attacks.  A misconfiguration may make it possible to
> inject untrusted traffic onto your trusted network by spoofing VLAN
> headers.  A method for bi-directional traffic was recently posted
> (sorry, I don't have the ref handy) by using a publically addressable
> host.
>
> 3. Everyone makes mistakes.  By combining untrusted and trusted
> networks on a single switch, the effects of a configuration mistake
> could be amplified.
>
> 4. Cisco, in my opinion, isn't the best or most secure firewall available.
>
> 5. Collapsing the network to that level might make it harder to
> monitor and control.  For example, how would you put a network based
> IPS between the firewall and the internal segment if you wanted to
> impliment one in the future?
>
> Hope this helps,
>
> Chris
> www.riosec.com
>
> On 8/11/06, cableguy clueless <cluelesscableguy () gmail com> wrote:
> > Guys, I need to ask a favor, my boss knows nothing of IT
> > infrastructure, and our "cableguy" (manages the firewall through a
> > third party contract) proposed to him an architecture as  follows :
> >
> > 2 cisco 6509 each with firewall blade in them. These function as core
> > switches for a 1000 users site with lots of vlans and FW roules
> > between the vlans (oh and we are a big production site that relies on
> > these cores to let our ciritical bussiness process machines
> > communicate to the servers).
> >
> > He wants to create 2 vlans, 1 for untrusted traffic and 1 vlan for DMZ
> > machines and assign physical ports to these to connect to the
> > internet. The DMZ vlan would also have some physical ports. These
> > ports would not be on the core switch but on the access layer switches
> > that are fiber attached to the distribution switches that attach to
> > the cores...
> >
> > Does anyone care to comment on the security issues a setup as this
> > would pose? would this be pentest bonanza for you guys? and what would
> > the hackers make of a dmz vlan living in a big switch together with
> > other vlans?
> >
> > I have some ideas myself, but would appreciate your take on this. I
> > know this is the pentest list but it is you guys who get to poke holes
> > in these designs...
> >
> > CCG
> >
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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 
most comprehensive solutions to meet your application security penetration 
testing and vulnerability management needs. You have an option to go with a 
managed service (Cenzic ClickToSecure) or an enterprise software 
(Cenzic Hailstorm). Download FREE whitepaper on how a managed service can 
help you: http://www.cenzic.com/news_events/wpappsec.php 
And, now for a limited time we can do a FREE audit for you to confirm your 
results from other product. Contact us at request () cenzic com for details.
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