University of Houston – Downtown 1 Last edited by Robertson, Cheryl on 12/21/18
Computer Virus Fact Sheet
What is a computer virus?
Computer viruses have impacted a significant number of computers
worldwide. A computer virus is a (hidden) program, which invades
your computer. A computer virus contains code that has the potential
to cause damage and/or perform unwanted/unauthorized functions.
How does a virus work?
A computer virus performs two basic functions: it copies itself from machine to machine
(self- reproducing), and it executes the instructions the perpetrator has planned.
A computer virus exhibits three characteristics: a replication mechanism, an activation mechanism,
and an objective. The replication mechanism searches for other programs to infect, if it finds any, it
inserts the hidden instructions in the program then it modifies the execution sequence of the
program's instructions such that the hidden code will be executed whenever the program is invoked.
The activation mechanism checks for the occurrence of some event. When the event occurs, the
computer virus executes its objective.
What damage can a virus do?
A computer virus is only one of the many kinds of threats to the security and integrity of UHD's
computing resources. Like other threats, a computer virus can cause unwanted alteration or loss of
data.
The damage done depends on the computer virus. There are viruses that do no harm, others
that just annoy the user, and still others that can completely destroy all your data files. In some
cases, your machine can even be rendered unusable.
How many viruses are out there?
Computer viruses have impacted a significant number of computers over the past few years.
There are currently over 10,000 known computer viruses worldwide. Over 200 new viruses are
being discovered every month.
How do they spread?
Viruses are usually spread by media/programs swapped through electronic bulletin boards or the
internet.
What are the symptoms and indications of a computer virus infection?
Some computer viruses alert you to their presence by putting an unexpected message on your
screen. Others use more subtle methods.
Things to watch for:
•
programs taking longer to start or running more slowly than usual
•
disk accesses seem excessive for simple tasks
