Information Technology Reference
In-Depth Information
It may be relatively easy to
determine someone's user-
name. However, finding out
someone's password is often
much more difficult. People
who want to break into a sys-
tem or account often attempt
password cracking
—that
is, they attempt to identify
a user's password. Password
cracking can be accomplished
in several ways, for example,
by guessing, using a
keylog-
ger
(see Figure 11.2), engag-
ing in
social engineering
,
and using password-cracking tools.
password cracking
The act of attempting to
identify a user's password in order to gain access
to a system or program.
keylogger
A piece of hardware or a software pro-
gram that captures every keystroke a user types.
Figure.11 2
A hardware keylogger. This model
looks similar to a flash drive.
social engineering
The art of obtaining
someone's password either by befriending her or
tricking her into sharing it.
Malicious Programs
As noted in the preceding section, computer criminals engage in a wide
variety of activities to compromise your computer system, data, and
online identity. They are aided in their efforts by various types of mali-
cious software, grouped together under the title
malware
. This section
outlines the main types of malware programs.
malware
Harmful or maliciously created soft-
ware, such as a virus or spyware.
Viruses
A
virus
is a piece of malicious software that is installed without the user's
knowledge or consent. When executed, the virus program replicates and
spreads to “infect” other computer programs, data files, or even the boot
sector of the hard drive.
virus
A type of malware that attaches itself to an
executable file and spreads to other files when the
program is run.
Viruses often carry a malicious payload. For example, a boot-sector virus
might stop the computer from loading the operating system. Some viruses
might delete all files of a certain type—for example, Word documents.
Other viruses may simply have annoying consequences—perhaps opening
and closing the CD drawer. Some viruses hide as long as they can so they
can do as much damage as possible before being discovered. New viruses
appear virtually every day, so it is vital that you take precautions and pro-
tect yourself from them.
The most common way for a virus to spread is for a user to open an
infected email attachment or Internet link without having virus protec-
tion in place. This allows the malicious software to gain access to the sys-
tem. If the infected file is sitting in RAM memory and you run another
program, the virus attaches a copy of itself to the second program—and
so on and so forth.
Worms
A
worm
is similar to a virus in that it may have a malicious payload.
However, worms are designed to automatically spread from computer to
computer over a network or the Internet. Like viruses, the consequences
worm
A malicious computer program that
spreads itself to other computers over a network
or the Internet.
