What Do They Want from You?
So the question remains: What could anyone possibly find on your computer or
home network that would be of value to him or her? The answer might surprise you.
For example, they might want to:
1 Steal your Microsoft Money and Quicken files, where you store personal
financial information.
2 Get their hands on your personal saving and checking account numbers.
3 Search for your personal pin numbers.
4 Steal electronic copies of your taxes that have been prepared using desktop
tax reporting applications.
5 Steal your credit card numbers or any other financial information that is of
value.
6 Steal important business information on your computer that might be of
value to a competitor.
7 Launch distributed denial of service attacks against other Internet computers
and Web sites.
All these types of information can easily be captured and sent to the hacker using a
worm program, as depicted in Figure 1.4. A worm can be initially implanted on your
computer by hiding inside an e-mail attachment which, when double-clicked,
silently installs the worm on your hard drive. The worm then goes to work searching
your hard disk for valuable information that it can relay back to its creator.
Money and personal secrets might not be the only things of value your computer
can provide to hackers. Some people simply delight in causing trouble or playing
practical jokes. It is not fun to find out that somebody has hacked on to your computer
and deleted important files or filled up your hard drive with useless garbage,
but to some crackers this is a form of amusement.
A cracker can also take control of your computer without your knowledge and use it
and thousands of other computers to launch attacks on commercials Web sites and
other corporate communications systems. Crackers achieve this task by breaking
into individual computer systems and planting Trojan horses that, after installed,
communicate back to the cracker’s computer and perform whatever instructions they
are told to do. To prevent this sort of silent hostile takeover, you need to install a personal
firewall and configure it to block all unapproved outgoing traffic from your
computer. As you will see in Chapter 3 you can configure your firewall with a list of
approved Internet applications such as Internet Explorer and Outlook Express. Your
personal firewall will then deny access to the Internet to any application that is not
on this list, including any Trojan horse applications.
The term Trojan horse comes from the trick that the Greek attackers used to penetrate the defenses of the city of Troy. It describes a program that sneaks onto your computer by hiding within a seemingly legitimate piece of software. The horse later begins to run amuck. Back Orifice made the Trojan horse software attack famous. Back Orifice is a Trojan horse program whose name mimics the Microsoft Back Office suite of network applications. Once planted, the Back Orifice program provides the hacker with complete control over the infected computer.