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

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1: Introduction

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

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....

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