Lesson 7 Intrusion Prevention Systems. UTSA IS 3523 ID & Incident Response Overview Definitions...

Lesson 7Intrusion

Prevention Systems

UTSA IS 3523 ID & Incident Response

Overview

• Definitions• Differences• Honeypots• Defense in Depth


Intrusion Detection Systems • IDS – “Combination of Hardware and Software

Designed to Detect Suspect Activity on a Network”

• Types of IDS Solutions and Deployments– Network, Host and Application

• Detection Methods – Signature, Anomaly and Behavior Based

• IDS Evolution – Three Evolutions of IDS Products and Solutions – Detect, Shore-Up and Proactively Block (IPS)


What Should an IDS Do

• Detect scans against a network– Helps determine who might attack

• Provide info on DoS attacks

• Alert on possible worm infections

• Alert administrator about brute force, password cracks, dictionary attacks, etc.

• Block Some Worms – Code Red, Nimda, SQL Slammer– If Linked to a Firewall


IDS Challenges • Performance

– Network Based IDS Systems must handle large throughput, i.e. large amounts of packets

• Reliability - false positives plague early IDS– Misnomer: “bad string development”

• Cost – Extensive IDS Deployments Can Be a expensive

• Labor intensive– IDS tuning and maintenance requires much expertise

• Host based IDS systems can use up lots of resources on their hosts


Intrusion Prevention Systems• HW/SW that pro-actively block attacks

– Little or no human intervention

• Normally stand alone solutions but may integrate with firewalls, switches or routers

• Usually less maintenance than traditional IDS

• Usually requires more set-up—have to know your network traffic

• May be network or host based

• Emerging sub-sector of IDS market


What an IPS Can Do

• Detect and Block Network

• Block DoS attacks in real time

• Completely stop nuisance attacksBlock Worm propagation


Intrusion Detection –vs- Intrusion Prevention

• Often viewed as a blending of firewalls and IDS• Definition: A device (HW or SW) that has the

ability to detect an attack and to prevent the attack from being successful.– Must handle known and unknown attack methods

• Will look at 4 general types of IPS– Inline NIDS– Layer Seven Switches– Application Firewall/IDS– Deceptive Applications

Inline NIDS

From: http://www.securityfocus.com/infocus/1670

Offers the capabilities of a regular NIDS with the blocking capabilities of a firewall. Examines traffic, decides whether to send it on or not.Generally needs to know what it is looking for (e.g. signatures).


Layer Seven Switch• Usually think of switching as a layer 2 function.• Due to bandwidth intensive content, some

switching now going on a layer seven (e.g. load balancers) where application traffic can be examined.

• Decisions can be made as to whether data is sent.• Generally needs to know what it is looking for.• One of best uses is to address DoS attacks.


Application Firewall/IDS

• Loaded on each server to be protected.• Customized for the application to be

protected.• Don’t look at packets, look at API calls,

memory management (for overflows), and interaction of user with OS.

• Can help prevent new attacks since it is not looking for signatures but rather attempted actions.


Deceptive Applications

• Idea has been around for a while• Concept is to first watch network to

determine profile of normal traffic• If traffic comes along later, such as scan for

a service on a system that doesn’t exist, then respond with bogus data so packets are “marked” and future traffic from attacker will be noticed and handled easily.

Deceptive Applications

No system10.1.1.20!

From: http://www.securityfocus.com/infocus/1670


Network Commercial IPS

• Cisco Secure IDS (son of Netranger)

• ISS Proventia

• NetScreen IDP-500

• McAfee Intrushield 4000

• TippingPoint UnityOne -1200

• TopLayer Mitigator IPS-2400


IPS Pictures

http://www.nss.co.uk/ips/edition1/nai-intrushield/fig1-Group_all.png

http://www.iss.net/products_services/enterprise_protection/proventia/g_series.php


Honey Pot

• New Player..not quite an IDS, but results are the same

• Decoy System

• Mislead Hackers

• Begin Incident Response (early!)


Defense-in-Depth

• Key Security Concept

• Usually considered in shallow ways

• We don’t so good job implementing organization wide

• Very seldom do we simultaneously simplify and improve security


5 Different Control Types

• Protect - firewalls/router ACLs

• Detect - IDSes

• Recover - Incident Response/Recovery Plans

• Deter - Laws and marketing

• Transfer - Insurance


Problem with Approaches

• Each control has binary effectiveness

• No security is perfect

• Better approach is “synergistic security”– Success hinges on redundancy of security

controls


Security Synergy• Baye’s Theorem:

– Effectivness(TOTAL)= 1-((1-E1)*(1-E2)*(1-E3)…)

#Synergistic

Controls Efficiency of Each Control

60% 70% 80% 90%

1 60 70 80 90

2 84 91 96 99

3 93.6 97.3 99.2 99.9

4 94.7 99.2 99.8 100

5 99 99.8 100 100


The Challenge

• “The real challenge is for people who can write good models for the data that comes out. The problem we have is that different enterprise networks create quite different traffic. Trying to model it and pull out interesting patterns with it while minimizing false positives and things like that, is very difficult.

• Bob Gleichauf• Cisco Systems


Summary

• IDSes are still maturing• IDSes are not silver bullets…they cannot

overcome inherent security weaknesses• But, IDSes are usually the primary “detectors”

to start the incident response process• Synergistic Security (Defense-in-depth) is the

key

Lesson 7 Intrusion Prevention Systems. UTSA IS 3523 ID & Incident Response Overview Definitions...

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