What is a virus?
A computer virus is a program
that spreads by first infecting files or the system areas of a computer
or network router's hard drive and then making copies of itself. Some
viruses are harmless, others may damage data files, and some may destroy
files. Viruses used to be spread when people shared floppy disks and
other portable media, now viruses are primarily spread through email
Unlike worms, viruses often require some sort
of user action (e.g., opening an email attachment or visiting a
malicious web page) to spread.
What do viruses do?
virus is simply a computer program--it can do anything that any other
program you run on your computer can do. Some viruses are designed to
deliberately damage files, and others may just spread to other
What is a worm?
A worm is a type
of virus that can spread without human interaction. Worms often spread
from computer to computer and take up valuable memory and network
bandwidth, which can cause a computer to stop responding. Worms can also
allow attackers to gain access to your computer remotely.
What is a Trojan horse?
Trojan horse is a computer program that is hiding a virus or other
potentially damaging program. A Trojan horse can be a program that
purports to do one action when, in fact, it is performing a malicious
action on your computer. Trojan horses can be included in software that
you download for free or as attachments in email messages.
Can I get a virus by reading my email messages?
viruses, Trojan horses, and worms are activated when you open an
attachment or click a link contained in an email message. If your email
client allows scripting, then it is possible to get a virus by simply
opening a message. It's best to limit what HTML is available in your
email messages. The safest way to view email messages is in plain text.
How can I avoid a virus infection from email?
users get viruses from opening and running unknown email attachments.
Never open anything that is attached to an email message unless you know
the contents of the file. If you receive an attachment from a familiar
email address, but were not expecting anything, you should contact the
sender before opening the attachment. If you receive a message with an
attachment and you do not recognize the sender, you should delete the
Selecting the option to view your email messages in plain text, not HTML, will also help you to avoid a virus.
What are some tips to avoid viruses and lessen their impact?
- Install anti-virus software from a reputable vendor. Update it and use it regularly.
addition to scanning for viruses on a regular basis, install an "on
access" scanner (included in most anti-virus software packages) and
configure it to start each time you start up your computer. This will
protect your system by checking for viruses each time you run an
- Use a virus scan before you open
any new programs or files that may contain executable code. This
includes packaged software that you buy from the store as well as any
program you might download from the internet.
- If you
are a member of an online community or chat room, be very careful about
accepting files or clicking links that you find or that people send you
within the community.
- Make sure you back up your
data (documents, bookmark files, important email messages, etc.) on disc
so that in the event of a virus infection, you do not lose valuable