RE: Firewalls (was Re: IDS evaluations procedures)

["Swift, David" <dswift () ipolicynetworks com>]

Right up front, I'll admit I work for a vendor, but...

1. There are a growing number Intrusion Detection/Intrusion Prevention
Systems that have integrated firewall.
2. IPS is a significant step in the right direction, and does things a
firewall can't. If you have doubts, try using Firewalker to pinpoint
holes in your firewall, and map network devices PAST the firewall
perimeter. If I can find them, I can attack them. Then craft a few
attacks with Nessus and send a fragmented attack right on through the
firewall at a given target.

iPolicy started a company with the premise that security integration was
where things were headed. We built a good firewall, that after 5 years
of revisions now has an easy to use interface, AND we incorporate a good
IDS/IPS engine. 

Regardless of the type of networking device, every packet has to be
inspected for certain pieces of data...Source Address, Destination
Address, Source/Destination Protocol.... 

If you've already read the packet, why not apply intelligence beyond
allow/deny/NAT/PAT and actually inspect the data payload? IDS is a
natural extension. 

Oh, and by the way while you have the data payload open for inspection,
why not apply intelligent rules to look for MalWare in the payload? Then
toss the bad payload packets away with everything else you've already
filtered with the firewall rules.

Now integrated the rules into a common rule tree, and you can eliminate
the latency of multiple devices in serial to accomplish the same thing. 

By the way, URL filtering, Anti-Virus Scanning, Peer-to-Peer, and
Instant Messaging all make sense in the same device as well. 

Essentially instead of a static rule engine, integrated security devices
are Sniffers on steroids with good rule trees to weed out bad packets,
regardless of why they're not wanted.
___________________________________________
David Swift         Sr. Systems Engineer
CISSP, MCSE, MCNE, CCNA, AIX-CSA, SUN-CSA

-----Original Message-----
From: Mike Barkett [mailto:mbarkett () nfr com] 
Sent: Friday, July 22, 2005 12:56 PM
To: 'Richard Bejtlich'; 'Nick Black'
Cc: focus-ids () securityfocus com
Subject: RE: Firewalls (was Re: IDS evaluations procedures)

> -----Original Message-----
> From: Richard Bejtlich [mailto:taosecurity () gmail com]
> Sent: Thursday, July 21, 2005 7:56 AM
>
> Hi Nick and list,
>
> If someone configures their layer 3/4 firewall to block, say, ports
> 111 TCP and 445 TCP, and let everything else pass, we would agree that
> is a poor deployment model.  People still do this, unfortunately.
>
> If someone configures their layer 7 firewall (aka IPS) to block
> traffic identified by signature, anomaly, vulnerability, whatever, and
> let everything else pass, now we're discussing the way almost everyone
> deploys IPSs.

I've heard/read this wrongheaded argument and its variants over and over
again.  It goes sort of like this: "y'know, in the end IPS is just a
firewall, and so now I'll proceed to judge it by firewall standards, and
since it doesn't match my perception of a firewall, it's a poor
solution."
That is called circular reasoning.

Firewalls have evolved as full-fledged network participants, and some
folks
would argue the firewall is the key component of a well designed
network.
Almost everyone uses them for NAT, many people use built-in VPN
functionality, and I'll even frequently see people running routing
protocols
on the firewall.  This is all in addition to "letting in what's good and
denying everything else."  

The IPS wields a big sanity stick and uses it frequently to wallop
stupid
traffic.  We all know there's lots of stupid traffic out there that
still
gets through the firewall.  A high-quality IPS will also be effective at
warding off real attackers and preventing insiders from doing prohibited
things.

This discussion so far has been about what is out there and what people
do.
Today, in 2005, an IPS is a device that compliments your traditional
firewall, whether it's a L3/4 device or a proxy, or whatever.  Today,
you
can get a firewall to be smarter about the traffic it lets through, and
you
can set up an IPS to "let in what's good and deny everything else."  I
know
people who DO use their IPS this way.  Additionally, there are some
products
that claim to do it all, and truthfully that is probably where things
are
eventually going.  But what you cannot do today, in 2005, is cut one
check
to one vendor and receive a single box that contains a best-of-breed IPS
and
a top notch firewall.  That is, unless you cut the check to a VAR that
sells
NFR and some firewall and they ship them in the same box. :-D  My point
is,
we should not ditch the technology simply because it is not nirvana.


> I have not heard anyone defining and passing "authorized" traffic and
> denying everything else via IPS.  In fact, a hot hardware item these
> days are inline bypass switches to avoid inline IPSs that fail.
> "Better to keep the traffic flowing than fail closed!" is the
> rationale.

Two fail passthrough IPSes deployed serially can give non-HA networks a
level of availability previously only found on fully redundant networks.
Also, any IPS worth its salt will give the user the ability to
disable/enable this feature at will.  When used without another IPS or
firewall, yes, fail passthrough is a poor security measure.  However,
some
organizations choose to accept this risk, and many actually implement
the
safeguard properly.

> I detest the term IPS, as it is a pure marketing term.  It was created
> by companies that needed to define a new access control product niche
> to compete against the firewall giants of the early 2000s.   (All
> defensive measures are trying to prevent intrusions.)

I agree, the term IPS is somewhat akward, especially to anyone with a
background in firewalls.  I also believe that purism rarely creates
value
for anyone, and security is no exception.  It is a growing pain of any
market to endure tweener products and fad "marketing terms" as the
technology gets fleshed out.  As I said before, we live in today, and
this
is where the technology is.
 
> However, I am not disrespecting the technology. Anything which can
> make smarter access control decisions is extremely helpful and an
> important part of the security arsenal.

Good!  I have some IPS to sell you.  (There's my vendor disclaimer.) :)

-MAB

--
(nfr)(security)
Michael A Barkett, CISSP
Vice President, Systems Engineering
5 Choke Cherry Road, Rockville, MD 20850


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