We often accept the general perception that any destructive program, run on any
computer, is a virus. Not so, as a matter of fact.
Perhaps thus a mistake made in the late 1980's will be excused. Back then a mere
handful of people had even the first clue as to what the term might mean.
It wasn't until 1993 that the term of 'Virus' was actually defined in print in
Merriam-Webster's Collegiate Dictionary: "a computer program usually hidden within
another seemingly innocuous program that produces copies of itself and inserts them into
other programs and that usually performs a malicious action (as destroying data)."
The origion of its name can be simply explained thus: like the biological virus, a
computer virus is small, makes copies of itself, and cannot exist without a host. When
personal computers became popular, PC viruses began to appear (in 1986-1987), at first
intended as jokes, or developed for research or demonstration purposes.
A virus is program code, that is, a set of instructions to be executed by the computer
when a program infected by the virus is run. The second essential component of a virus is
that it must be replicate (to make an exact copy of themselves). Some replications
are relatively simple. And others are complicated. In order to be classified as a virus,
the code must contain instructions that copy the virus code to another host. This is one
property that all computer viruses have in common. Other properties may include
installation in memory of the virus code to aid in subsequent infections, stealth,
mutation, trigger and damage. Not all viruses have all of these properties. While some
viruses merely infect, others can cause catastrophic damage to the computer's file system.
A computer virus must be an accessory on top of some other program or document in order
to get executed. Once it is running, it is then able to infect other programs or
documents. Just like the biological viruses, they are contagious. Early viruses were
pieces of code attached to a common program like a popular game or a popular word
processor. A person might download an infected game from a web site and run it on their
own computers. The virus loads itself into memory and looks around to see if it can find
any other programs on the disk. If it can find one, it modifies it to add the virus's code
to the unsuspecting program. As a matter of fact, there is no way for a user to know that
the virus was ever ran. Next time, when both of the programs get executed, they each can
get other programs infected also. And therefore, the cycle of infection continues. This is
how viruses spread.
Notice that all computer viruses are created by people who know how to write computer
programs.
So, remember that a virus is a program that replicates. A virus does not necessarily
have to do anything destructive, it just have to spread. Unfortunately, most viruses don't
replicate themselves, otherwise, they would not be the headache problem of the modern
technology. Virus do everything from printing a silly message on the screen to erasing all
of your data.
A computer virus must be an accessory on top of some other program or document in order
to get executed. Therefore, the host program is used to hide the activities of the virus
and cause the virus instructions to be activated without the user knowing it. Once it is
running, it is then able to infect other programs or documents. Just like the biological
viruses, they are contagious. Viruses and worms spread fastest among computers networked
on a LAN, especially when e-mail file attachments are involved.
Basically, it's a process in which to protect the data stored in your computer either
by prevention or detection of unauthorized use of your computer. Prevention immunizes your
system from unauthorized users (also named as "intruders") from accessing your
system. While detection determines whether someone has broken into your computer
successfully.
Intruders (known also as hackers) are not interested in your personal identity at all.
They do not care who you are, the only thing that matters is that they need your computer
to launch attack on other computer systems. This is how they cover up their tracks by
creating a false location to hide their true identity.
The fact is that corporate and government networks are typically protected by many
layers of security, ranging from network firewalls to encryption.
In addition, they usually have support staff who maintain the security and availability of
these network connections. Although your ISP is responsible for maintaining the services
they provide to you, you probably won't have dedicated staff on hand to manage and operate
your home network. In this case, it's entirely up to you to take reasonable precautions to
secure your computers from accidental or intentional misuse. And this is why we are here
for you.
