Defense-in-Depth, Part 2: Advanced Intrusion Defense

Defense-in-Depth, Part 2:Advanced Intrusion

DefenseJoel SnyderOpus Onejms@opus1.com

Traditional perimeter technology is being…… Supplemented?

A firewall is not just a firewall any more Firewalls now have “advanced application

intelligence”• Actually, they had that already, but the

marketroids had to keep themselves busy Firewalls now are “intrusion prevention

systems”• Isn’t every firewall an intrusion

prevention system? Firewalls now do virus scanning, content

scanning, and ironing Application-layer firewalls are needed to

protect legions of inadequate web programmers

IDS has been replaced by IPS• (No, I don’t believe that, I’m just

repeating awful rumors) Worms now outnumber viruses in

your e-mail by a factor of 20 to 1 Spam represents 50% to 75% of all

e-mail you receive

Key question: Do you need this? Do you need to buy (or

upgrade) to a bigger, smarter, faster, more capable firewall?

Do you need to buy an IPS? …an application layer firewall? …a smarter IDS? …an SSL VPN device? Do I want an all-in-one thing? Do I want individual parts?

The answer you’ve been waiting for… is on the very next slide!

Should I buy a lot of this new security stuff?

And if I do buy this, what kind should I buy?

And where should I put it?And which product should I buy?

Answer: 42

I can’t tell you what is right for your network

I can tell you what products are out there and what they are doing

I can also tell you what the trends are in these products

But the hard work remains yours

So let’s look at what’s happening in the firewall business

March, 2004: Information Security sponsors research on new firewall technologies

Products from Check Point, Cyberguard, NetScreen, Nortel Networks, Symantec, Secure Computing, Watchguard

Support from Andy Briney, Neil Roiter at Information Security

http://infosecuritymag.techtarget.com/

Firewalls have been around for a very long time

“[AT&T’s gateway creates] a sort of crunchy shell around a soft, chewy center.” (Bill Cheswick, Design of a Secure Internet Gateway, April, 1990)

1989 1991 1993 1995 1997 1999 2001 2003 2005

First firewalls deployed in Internet-connected organizations

“Firewalls and Internet Security” published

TIS toolkit commonly available

Cisco buys PIX (Network Translation)

CheckPoint revenues cross $100m

WatchGuard introduces 1st FW appliance

Surely firewall makers have been busy since 1999 ?Clear market trends

FasterCheaperSmaller • New Guard:

NetScreen (Juniper), Watchguard, SonicWALL

• Old Guard: Cisco, Check Point

Clear product trendsAdd VPN features• Site-to-site• Remote Access (?)

Add policy-based URL control• Websense-type

Add interfaces • No longer just inside,

outside, DMZ

Surely, firewall makers have been busy since 1999 ?

Clear market trendsFasterCheaperSmaller • New Guard:

NetScreen (Juniper), Watchguard, SonicWALL

• Old Guard: Cisco, Check Point

Clear product trendsAdd VPN features• Site-to-site• Remote Access (?)

Add policy-based URL control• Websense-type

Add interfaces • No longer just

inside, outside, DMZ

Incremental improvements are not very exciting

Smaller, cheaper, faster: that’s greatVPNs, more interfaces: that’s greatBut what have you done for me lately?

To answer that, we need to digress to the oldest battle in all of firewall-dom: proxy versus packet filter!

Arguments between Proxy and Stateful PF continued

ProxyMore secure because you

can look at application data stream

More secure because you have independent TCP stacks

Stateful PFFaster to writeFaster to adaptFaster to runFaster also means

cheaper

Proxy-based firewalls aren’t dead… just slow!

Proxy

Packet Filtering

Src=10.1.1.99Dst=5.6.7.8

TCP/IP

Src=1.2.3.4Dst=5.6.7.8

Kernel

Inside network = 10.1.1.0/24

Outside net = 1.2.3.4

RTL

Process Space

Firewall Landscape: five years ago

IBM eNetworkSecure ComputingAltavista FirewallTIS GauntletRaptor EagleElronCyberguardUkiah Software

NetGuardWatchGuardSonicWALLCheck PointLivermore SoftwareMilkywayBorderwareGlobal Internet

Stateful Packet Filtering dominates the market

Stateful Packet Filtering

IP

Kernel

Check PointCisco NetScreen SonicWALL

Freeware-based products: Ipchains, IPF, Iptables, IPFW

FW Newcomers:Fortinet, Toshiba, Ingate, ServGate, many others

But… the core argument was never disputed

Proxy-based firewalls do have the possibility to give you more control because they maintain application-layer state information

The reality is that proxy-based firewalls rarely went very far down that pathWhy? Market demand, obviously…

Firewall Evolution:What we hoped for…

Additional granular controls on a wide variety of applications

Intrusion detection and prevention functionality

Vastly improved centralized management systems

More flexible deployment options

Firewall Evolution:What we found…

Additional granular controls on somea wide variety of applications

Limited intrusion detection and prevention functionality

Vastly improved centralized management systems

More flexible deployment options

Why? Market demand, obviously…

So what’s going on in the firewall business?

Products are diverging, not convergingPersonalities of products are distinct IPS is a step forward, but not challenging the world of

standalone productsRate of change of established products is slow

compared to new entries

What does this mean for me and my firewall?

Products are diverging

Personalities are distinct

IPS weaker than standalone

Change rate slow

Matching firewall to policy is hard; change in application or policy may mean changing product!

Aggressive adoption of new features unlikely in popular products; need new blood to overcome product inertia

Are Intrusion Detection Systems dead?

http://infosecuritymag.techtarget.com/

Massive Support from Marty Roesch, Ron Gula, Robert Graham

Products from ISS, Cisco, and Tenable

Cash and Prizes from Andy Briney and Neil Roiter

This is an IDS alert…

IDS saw a packet aimed at a protected system

IDS magic decoder technology correctly identifies this as “Back Orifice!”

This IDS alert ain’t no good

Last time I checked, FreeBSD 4.9 was not one of the supported platforms for BackOrifice…

Please don’t call that a false positive

IDS developers will jump down your throat

“False Positive” means the IDS cried wolf when there was no such attack• Usually the result of

poorly written signatures

Instead, let’s invent a complex multisyllable term:“non-contextual alert”

The IDS lacks “context”

IF the IDS knew that the destination system was not running Windows…

IF the IDS knew that the destination system was not running Back Orifice…

IF the IDS knew that there was no such destination system…

IF the IDS knew that the destination system was more hops away then TTL allowed…

IF IF IF the IDS knew more…

THEN the IDS could tell the IDS operator more about this attack

Ron Gula (Tenable) says that alerts are “raw intelligence.” They are data, but are not information yet. We need to turn them into “well-qualified intelligence” to start a war.

Roesch: “Target-Based IDS”

Target-based IDS Sensor• The sensor has knowledge

about the network• The sensor has knowledge

about the hosts

Target-based Event Correlation• The output of the

sensor is compared to knowledge of vulnerabilities

Target-based IDS has two components

Start with a normal IDS…1. IDS sensors generate

enormous dinosaur-sized piles of alerts;alerts are sent to the IDS console

2. Operator gets enormous dinosaur-sized headache looking at hundreds of thousands of alerts … and add

brains!

What does an IDS with brains look like?

Brains=knowledge + processKnowledge

Somehow figure out lots of information about • What systems are out

there• What software they

are running• What attacks they are

vulnerable to

Process Evaluate each alert

with the additional contextual knowledge and decide• To promote the alert• To demote the alert• That we don’t know

Can this quiet my IDS down? It could…

But none of the products I looked at have a feedback loop to the IDS!

Why don’t the scanners tell the IDS what ports to look on?

Why don’t the scanners tell the IDS what signatures to ignore?

Is this right for you?YES!

“I already have an IDS and I care about the alerts and I need some way to help prioritize them because I am drowning in alerts!”

“I need to get an IDS for alerts but don’t have the manpower to analyze the alerts.”

NO! “If I get this, my IDS will

be a self-tuning smooth-running no-maintenance machine.”

“I have no network security policy which says what to do when an alert occurs.”

Advanced Intrusion DefenseJoel SnyderOpus One

jms@opus1.com