Hardware Reference
In-Depth Information
a website. Be very careful what sites you use to download executable fi les! Another way
to get spyware is to run an ActiveX or Java component on a website you visit. A website
may seem like a good deal because it's free, but there are many unscrupulous site owners,
particularly in the adult entertainment industry, who exploit site visitors by infecting their
computers with spyware or adware.
Some antivirus software detects and removes spyware. There are also applications
designed specifi cally to remove spyware and adware from your system, such as Windows
Defender (discussed later in this chapter).
Software for Defending Against Malware
Three main classes of applications help protect your system against malware.
Antivirus
software
defends against viruses, worms, and Trojan horses;
antispyware
software defends
against adware and spyware; and
antispam
software reduces the amount of junk email you
receive.
There are also suites available that combine multiple security functions; for example,
Norton Security Suite includes antivirus, antimalware, and antispam features, along with
identity-protection tools, a fi rewall, a backup tool, and a PC tune-up tool. In addition,
there is some overlap between the types of threats each application guards against; for
example, an antivirus program may also target some types of nonvirus malware.
Antivirus Software
Antivirus software attempts to identify virus infections by scanning all the fi les on your
hard disk (or a subset of fi les that are most likely to contain viruses). Popular antivirus
programs include Norton Antivirus and McAfee VirusScan.
The website
www.av-comparatives.org/
provides a comprehensive
comparison and review of current antivirus applications. Take the time to
look through this site and draw your own conclusions about what may be
the best antivirus application for you.
Viruses are often concealed by a simple deception. They embed themselves inside an
application, redirecting the application's commands and code around themselves while
running as a separate task. One way antivirus programs detect a virus is by opening the fi le
and scanning the code, looking for this type of redirection. Some programming languages,
such as C++ and Java, generate code in a style that is sometimes wrongly accused by an
antivirus program of being infected.
Another way antivirus programs work is to scan the code of each executable fi le looking
for
virus signatures
. A virus's signature is an identifying snippet of its code, sometimes
called a
virus defi nition
. The antivirus program maintains a database of known virus
defi nitions; when it fi nds a match between its database and some code it fi nds in a fi le it
scans, it signals a warning that there may be an infection. As new viruses and other threats
