Computer Viruses: Past, Present And Future

In our health-conscious society, viruses of any type are an enemy. Computer
viruses are especially pernicious. They can and do strike any unprotected
computer system, with results that range from merely annoying to the disastrous,
time-consuming and expensive loss of software and data. And with corporations
increasingly using computers for enterprise-wide, business-critical computing,
the costs of virus-induced down-time are growing along with the threat from
viruses themselves. Concern is justified - but unbridled paranoia is not. Just
as proper diet, exercise and preventative health care can add years to your life,
prudent and cost-effective anti-virus strategies can minimize your exposure to
computer viruses.

· A history of computer viruses
· Who writes viruses - and how they can reach you
· The early warning symptoms of virus infection
· The real numbers behind the growth of viruses and their costs
· How viruses work - and how virus protection can stop them

What, Exactly, Is A Computer Virus?

A computer virus is a program designed to replicate and spread, generally with
the victim being oblivious to its existence. Computer viruses spread by
attaching themselves to other programs (e.g., word processors or spreadsheets
application files) or to the boot sector of a disk. When an infected file is
activated - or executed - or when the computer is started from an infected disk,
the virus itself is also executed. Often, it lurks in computer memory, waiting
to infect the next program that is activated, or the next disk that is accessed.

What makes viruses dangerous is their ability to perform an event. While some
events are harmless (e.g. displaying a message on a certain date) and others
annoying (e.g., slowing performance or altering the screen display), some
viruses can be catastrophic by damaging files, destroying data and crashing

How Do Infections Spread?

Viruses come from a variety of sources. Because a virus is software code, it can
be transmitted along with any legitimate software that enters your environment:

· In a 1991 study of major U.S. and Canadian computer users by the market
research firm Dataquest for the National Computer Security Association, most
users blamed an infected diskette (87 percent). Forty-three percent of the
diskettes responsible for introducing a virus into a corporate computing
environment were brought from home.

· Nearly three-quarters (71 percent) of infections occurred in a networked
environment, making rapid spread a serious risk. With networking, enterprise
computing and inter-organizational communications on the increase, infection
during telecommunicating and networking is growing.

· Seven percent said they had acquired their virus while downloading software
from an electronic bulletin board service.

· Other sources of infected diskettes included demo disks, diagnostic disks used
by service technicians and shrink-wrapped software disks - contributing six
percent of reported infections.

What Damage Can Viruses Do To My System?

As mentioned earlier, some viruses are merely annoying, others are disastrous.
At the very least, viruses expand file size and slow real-time interaction,
hindering performance of your machine. Many virus writers seek only to infect
systems, not to damage them - so their viruses do not inflict intentional harm.
However, because viruses are often flawed, even benign viruses can inadvertently
interact with other software or hardware and slow or stop the system. Other
viruses are more dangerous. They can continually modify or destroy data,
intercept input/output devices, overwrite files and reformat hard disks.

What Are The Symptoms Of Virus Infection?

Viruses remain free to proliferate only as long as they exist undetected.
Accordingly, the most common viruses give off no symptoms of their infection.
Anti-virus tools are necessary to identify these infections. However, many
viruses are flawed and do provide some tip-offs to their infection. Here are
some indications to watch for:

· Changes in the length of programs
· Changes in the file date or time stamp
· Longer program load times
· Slower system operation
· Reduced memory or disk space
· Bad sectors on your floppy
· Unusual error messages
· Unusual screen activity
· Failed program execution
· Failed system bootups when booting or accidentally booting from the A: drive.
· Unexpected writes to a drive.

The Virus Threat: Common - And Growing

How real is the threat from computer viruses? Every large corporation and
organization has experienced a virus infection - most experience them monthly.
According to data from IBM\'s High Integrity Computing Laboratory, corporations
with 1,000 PCs or more now experience a virus attack every two to three months -
and that frequency will likely double in a year.

The market research firm Dataquest concludes that virus infection is growing
exponentially. It found nearly two thirds (63%) of survey respondents had
experienced a virus incident (affecting 25 or fewer machines) at least