Viruses
The term ’computer
virus’ has gone through various changes of meaning throughout the evolution of
computer technology. Regardless of the
definition, a virus is malicious in that users have no choice about it in the
event of infection. In the most general
sense, a virus is an executable code that seeks to replicate on a host system
and spread to other computers through various means of transmission. Before the widespread use of the Internet,
the term ’virus’ was used for malicious code that was spread through floppy
disks, as this was the only means to transmit data. Now, viruses have taken second place to the new wave of ’worms’
that propagate through networks without the need to infect host files.
The severity of
viruses and worms can vary from completely benign to overtly damaging. In the worst case, a virus or worm can
completely disable a computer. Milder
cases will reduce a computer’s overall performance by using up valuable system
resources. Weak viruses tend to have
poor code that won’t affect your system at all.
Traditional Viruses
The traditional
virus requires the user to execute a program that is already infected. Transmission usually occurs through a
downloaded program or macro. For
instance, you might download a game or application and attempt to run it. If it’s infected, the virus will load into
your system and begin propagating to other files. As the virus spreads, the computer’s performance will begin
suffering as a result. Older viruses
don’t use executable programs as their host.
Many old viruses infected the ’boot sector’ of a floppy disk. For this type of virus, a user would have to
attempt to boot his or her computer from the infected floppy disk. From there, the code would be executed and
the virus would infect the system.
Today, viruses are not such an immediate threat due to advancements in
anti-virus software. A careful user can
avoid a large majority of viruses simply by scanning suspicious files before
they are run.
Worms
On the other hand,
worms have become the dominant form of computer infection since the dawn of the
Internet. Worms do not require host
files to infect. Rather, they take
advantages of vulnerabilities in browsers and e-mail programs. Once you’ve received a worm (usually through
e-mail), it can open ’back doors’ in your system to effectively co-opt your
computer for its own use. Worms tend to
make copies of itself and send those copies to other computers by using your
e-mail software. For instance, a worm
may send itself to everyone on your contacts list without your knowledge. Because of this feature, worms are known to
seriously bog down the Internet when they reach their peak activity as millions
of e-mails may be sent as a result.
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