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Counter Hack: A Step-by-Step Guide to Computer Attacks and Effective Defenses

Counter Hack: A Step-by-Step Guide to Computer Attacks and Effective Defenses

by Edward Skoudis, Radia Perlman

The Next Generation Hacker Book

The step-by-step guide to defending against hacker intrusions!

  • Defend against today's most powerful hacker attacks!
  • Hands-on, step-by-step techniques for UNIX/Linux and Windows environments
  • Intrusion detection: New evasion techniques—and countermeasures
  • By


The Next Generation Hacker Book

The step-by-step guide to defending against hacker intrusions!

  • Defend against today's most powerful hacker attacks!
  • Hands-on, step-by-step techniques for UNIX/Linux and Windows environments
  • Intrusion detection: New evasion techniques—and countermeasures
  • By the security expert who demonstrated hacking to the U.S. Senate!

This easy-to-use, step-by-step guide will empower network and system administrators to defend their information and computing assets—whether or not they have security experience. In Counter Hack, leading network security expert Edward Skoudis presents comprehensive, insider's explanations of today's most destructive hacker tools and tactics-and specific, proven countermeasures for both UNIX and Windows environments. Skoudis covers all this and more:

  • Know your adversary: from script kiddies to elite attackers
  • A hacker's view of networks, TCP/IP protocols, and their vulnerabilities
  • Five phases of hacking: reconnaissance, scanning, gaining access, maintaining access, and preventing detection
  • The most dangerous and widespread attack scenarios—explained in depth
  • Key hacker tools: port scanners, firewall scanners, sniffers, session hijackers, RootKits, and more
  • How hackers build elegant attacks from simple building blocks
  • Detecting and preventing IP spoofing, covert channels, denial of service attacks, and other key attacks
  • How hackers cover their tracks—and how you can uncover their handiwork
  • A preview ocountermeasures

Whatever your role in protecting network infrastructure and data, Counter Hack delivers proven solutions you can implement right now—and long-term strategies that will improve security for years to come.

Editorial Reviews

The Barnes & Noble Review
When Ed Skoudis isn't explaining hacking techniques to U.S. Senate committees, he's busy helping major companies identify and resolve their most serious enterprise security vulnerabilities. And when he's not doing that, he's helping you. How, pray tell? By writing Counter Hack.

In this relentlessly hands-on book, Skoudis begins by identifying the most dangerous cracking tools -- the ones that are most popular and are causing the most damage. Then, he shows sysadmins exactly how to protect themselves from the havoc these tools can wreak in the wrong hands. There are techniques that respond to war dialers, port scanners, firewall scanners, sniffers, and session hijackers -- as well as practical countermeasures for IP spoofing, IP fragmentation, and even (to the extent possible) denial of service attacks.

Skoudis' solutions apply to UNIX and Windows environments, and are presented in relatively easy, step-by-step formats that ought to be usable by any competent sysadmin. There are five elements to cracking: reconnaissance and targeting, identifying vulnerabilities; gaining access; staying in once you're in, and avoiding detection. Unlike many security books, this one covers all five. It should go a long way towards helping you sleep at night. (Bill Camarda)

Bill Camarda is a consultant, writer, and web/multimedia content developer with nearly 20 years' experience in helping technology companies deploy and market advanced software, computing, and networking products and services. His 15 books include Special Edition Using Word 2000 and Upgrading & Fixing Networks For Dummies®, Second Edition.

Product Details

Prentice Hall Professional Technical Reference
Publication date:
Pearson Temp Security Series
Edition description:
Older Edition
Product dimensions:
7.12(w) x 9.20(h) x 1.58(d)

Read an Excerpt

1: Introduction

Computer attacks happen each and every day. Simply connect an innocuous computer to the Internet, and someone will try to pry into the machine three, five, or a dozen times each day. Even without any advertisements or links bringing attention to it, your machine will constantly get scanned by attackers looking for vulnerable prey. If the computer is used for actual business purposes, such as a commercial, educational, not-for-profit, or military site, it will get even more attention from attackers.

Many of these attacks are mere scans looking for holes in a system's armor. Others are really sophisticated computer break-ins, which occur with increasing frequency, as any glimpse of recent headlines demonstrates. In just a year's time, major banks have been victims of attackers who could view detailed information about customers' bank accounts. Attackers have stolen gobs of credit card numbers from e-commerce sites, often turning to extortion of the e-commerce company to get paid not to release customers' credit card information. Numerous online trading companies, news firms, and e-commerce sites were temporarily shut down due to major packet floods, causing the companies to lose revenue as customers turned to other sources, and erasing billions from the market capitalization of the victims. A major U.S.-based software development company discovered that attackers had broken into its network and stolen the source code for future releases of its popular products. The stories go on and on.

The purpose of this book is to illustrate how many of these attacks are conducted so that you can defend your computers against cyber siege. By exploring in detail the techniques used by the bad guys, we can learn how to defend our systems and turn the tables on the attackers.

The Computer World and the Golden Age of Hacking

Over the last several decades, our society has rapidly become very dependent on computer technology. We've taken the controls for our whole civilization and loaded them onto digital machines. Our systems are responsible for storing sensitive medical information, guiding aircraft around the world, conducting nearly all financial transactions, planning food distribution, and even transmitting love letters. When I was a kid, computers were for nerds and were avoided by most people. A decade ago, the Internet was the refuge of researchers and academics. Now, as a major component of our population stares into computer screens and talks on cell phones all day long for both business and personal use, these technologies dominate our headlines and economy.

I'm sure you've noticed that the underlying technologies behind computers and networks have many flaws. Sure, there are counterintuitive user interfaces and frequent computer crashes. Beyond these easily observed problems, there are some fundamental flaws in the design and implementation of the underlying operating systems, applications, and protocols. By undermining these flaws, an attacker can steal data, take over systems, or otherwise wreak havoc.

Indeed, we have created a world that is inherently hackable. With our great reliance on computers and the numerous flaws found in most systems, today is the Golden Age of Hacking. New flaws in computer technology are being discovered every day and widely shared through-out a burgeoning computer underground. By setting up a lab in the comfort of their own homes, attackers and security researchers can create a scaled down copy of the computer platforms used by giant corporations, government agencies, or military operations, using the same operating systems, routers, and other gadgetry as their ultimate target. By scouring the systems looking for new vulnerabilities, attackers can hone their skills and discover new vulnerabilities to exploit.

Computer technology is continuing its advance into every nook and cranny of our lives. Companies are now selling electric blankets with network connections, so you can make your bed warm and toasty from across your room or the planet. Andy Grove, the chairman of Intel, frequently discusses a future where your refrigerator will have an Internet connection so it can call the local grocery store and order more milk when you are running low. Scott McNealy, CEO of Sun Microsystems, talks about lightbulbs (yes, lightbulbs!) with network connections that allow them to make calls to lightbulb companies when a bulb is about to burn out. That way, the new bulb can arrive with a map to the dying bulb's location and be changed in real time. In the very near future, your car will have a wireless network connection supporting map downloads, remote troubleshooting, and—God help us—email while you drive. And what underlies all of these rapidly approaching future technologies? Computers and the networks that link them together.

With these advances, our current Golden Age of Hacking could get even more golden for the attackers. Think about it—today, an attacker tries to break into your computer by scanning through your Internet connection. In the near future, someone may try to hack into your net-work- enabled automobile while you are driving down the street. You've heard of carjacking? Get ready for the world of car hacking.

Why This Book?

If you know the enemy and know yourself,
you need not fear the result of a hundred battles.
If you know yourself but not the enemy,
for every victory gained you will also suffer a defeat.
If you know neither the enemy nor yourself,
you will succumb in every battle.

Sun Tzu, Art of War
Translation and commentary by Lionel Giles (part of Project Gutenberg)

“Golly gee!” you may be thinking. “Why write a book on hacking? You'll just encourage them to attack more!” While I respect your concern, unfortunately there are some flaws behind this logic. Let's face it— the malicious attackers have all the information they need to do all kinds of nasty things. If they don't have the information now, they can get it easily enough on the Internet through a variety of Web sites, mailing lists, and newsgroups devoted to hacking, as described in the concluding chapter of this book. Experienced attackers often selectively share information with new attackers to get them started on the craft. Indeed, the communication channels in the computer underground among attackers are often far better than the communication among computer professionals like you and me. This book is one way to help make things more even.

My purpose here is not to create an army of barbarian hackers mercilessly bent on world domination. The focus of this book is on defense. To create an effective defense, we must understand the offensive tools used by our adversaries. By seeing how the tools truly work and understanding what they can do, not only can we better see the needs for good defenses, but also we can better understand how to apply the appropriate defensive techniques.

This book is designed for system administrators, security personnel, and network administrators whose jobs require them to defend their systems from attack. Additionally, other curious folks who want to learn how attackers work and techniques for defending systems against attacks can benefit. The book includes practical recommendations for people who have to deal with the care and feeding of systems, keeping them running and keeping the bad guys out. With this understanding, we can work to create an environment where effective defensive techniques are commonplace, and not the exception. As good ol' Sun Tzu said, you must understand your enemy's capabilities as well as your own. For each offensive technique described in this book, real-world defenses are also described. You can measure your own security capabilities against these defenses to see how you stack up. Where your policies, procedures, and systems fall short, you can implement appropriate defenses to protect against the enemy. And that's what this book is all about: Learning what the attackers do so we can defend ourselves....

Meet the Author

Edward Skoudis is Vice President of Security Strategy for Predictive Systems, a leading independent infrastructure network consulting company, helping global enterprises and service providers harness the power of network technology. His specialty is identifying and resolving security vulnerabilities in UNIX, Windows, firewall architectures, and Web servers. Skoudis is a frequent speaker at major security conferences such as SANS and has demonstrated hacker techniques for the United States Senate.

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