Who can forget the way the world was frozen with the threat of the "Millennium Bug"? While people around
the globe should have been counting down to a phenomenal celebration, we were too busy preparing for
certain doom and gloom beset by a computer virus. Of course, the clock struck twelve on January 1, 2000
and a new millennium still began, bug-free.
Those unfortunate enough to have had to deal with a computer virus knows all too well the damage that
can be done. From taking on annoying quirks, to erasing files, to fully obliterating computers or
entire systems, the powerful effect of a computer virus is nothing to sneeze at. Computer viruses pose
real threats that can be minimal, or can cause worldwide destruction.
In computer security technology circles, the definition of a computer virus is a "self-replicating
program that spreads by inserting copies of itself into other executable code or documents". A computer
virus behaves in a manner similar to a biological virus, which spreads by inserting itself into living
cells.
Extending the analogy, the insertion of a computer virus into a program is termed as an "infection" and
the infected file (or executable code that is not part of a file) is called a "host". Viruses are one of
several types of malicious software, also known as "malware". The term "virus" is frequently extended to
refer to worms, Trojan horses and other sorts of malware. These are less common than they used to be,
still, so the inclusion of these types of malware can be confusing to computer users. This confusion
can have serious implications, as it can lead to a focus on preventing one genre of malware over
another, potentially leaving computers vulnerable to future damage. The basic rule holds that computer
viruses can only damage software, not hardware.
Viruses have targeted in the following types of hosts:
A computer virus by nature is destructive, but others are created solely for the annoyance factor. Some
viruses pester computer users with a delayed payload, also known as a "bomb". For example, a bomb virus
might display a message on a specific day, or wait until it has infected a certain number of hosts. A
time bomb occurs on a particular date or time, and a logic bomb occurs when the computer user takes an
action that triggers the bomb. However, the predominant negative effect of viruses continues to be their
uncontrolled self-reproduction, which wastes or overwhelms computer resources.
To hinder the continuous spread of computer viruses, programmers have created anti-virus software.
still, a fast infector can infect every potential host file that it's able to access. This presents a
special problem to anti-virus software. A virus scanner will perform a system-wide scan, accessing every
potential host file on the computer. If the virus scanner fails to notice that a virus exists in the
computer's memory, the virus can "piggy-back" on the virus scanner, and infect every file that is
scanned. Fast infectors rely on their incredible spreading rate. To combat the problem, certain
anti-virus software programs, like the well-known Spyware, are expanding to cover worms and other
threats.