The dark side of the web - The Computing Universe: A Journey through a Revolution - page 244

Fig. 12.1. An example of worldwide
botnet detections by the Microsoft
Digital Crimes Unit.
an overenthusiastic DEC marketing representative in 1978. Since then, the
volume of email spam has grown enormously. A 2003 study estimated that
more than half the email transmitted over the Internet was spam and that
more than 90 percent of all spam email was sent by just 150 people. By 2011,
according to one estimate, spam emails accounted for more than 80 percent
of all email sent over the Internet. Increasingly, these spam emails are not
sent by identifiable individuals but by zombie computers or botnets ( Fig. 12.1 ) as
we discuss in the following text. Botnets are made up of personal computers
belonging to ordinary users whose machines have been taken over by com-
puter malware that can be instructed to send out spam. Fortunately, spam fil-
ters are now available that can identify most spam emails and redirect them
straight to the “junk” email folder.
Malware is short for malicious software and means software that is designed
to gain unauthorized access to computers for a range of purposes, some rela-
tively harmless and others definitely criminal. The popularity of the Unix oper-
ating system in universities and businesses in the 1970s and 1980s originally
made Unix a prime target for black hat hackers, clever programmers who use
their skills to gain unauthorized access to computer files. Nowadays, because
of the success of the personal computer, Microsoft Windows is the operating
system most under attack. In many cases, the hackers are able to gain control
of the high-level system security privileges of the system administrators , the peo-
ple responsible for keeping the computer system running. On the other side in
this hacking war are the w hite hat hackers. These are ethical computer security
experts who specialize in finding security loopholes and in defending com-
puter systems from cyberattacks.
The techniques used by the black hats are many and varied. We begin
by discussing a selection of the most common techniques before looking at
the recent escalation in the use of malware for cyberwarfare. We then take a
brief look at modern cryptographic systems that are designed to keep Internet
communications secure from eavesdroppers and end with some comments on
cookies, spyware, and privacy.