What Is a Virus?
Start talking computer
virus to someone and there eyes go blank. Why? It's a conversation
not unlike that regarding root canal. No one really likes to talk
about them: they're uninteresting and basically they're about as fun
to talk about as hemorrhoids.
Viruses though are part
of our digital world, and much like smallpox and other human
diseases, they are here to stay. We just can't get rid of them. But
what are they exactly? Why can't we eradicate them once and for all?
Well, there are several
forms viruses take (okay, let the eyes start glazing over). We can
foresake the discussion of some of the older more anachronistic
types (at least initially) as they don't make the rounds as frequently anymore. So, how do email viruses
Simplistically, you get
an email with an attachment. You are led to believe the attachment
is a picture, video clip, audio clip or whatever. You double-click
on it and Windows looks at the extension of the attachment and runs
the appropriate program.
So if someone sends you
a picture file that ends in .JPG or .BMP or dozens of other
extensions, Windows will run whatever program you have set up to
view pictures with. If someone sends you an attachment that ends in
.DOC or .DOT, Windows will run Word. XLS, .XLW, .XLT will cause
Windows to run Excel, etc.
If someone sends you an
attachment that ends in .EXE, .BAT, .COM, .SCR or dozens of other
endings (extensions), Windows figures you want to run the program or
system command. Click here to see
a list of executable file extensions.
So someone writes a
program that basically says:
For each contact in the
Address Book do the following
Email.ToAddress = the contact's email address
Email.Subject = "Click me!"
Email.FromAddress = your email address
Email.Attachment = my virus program
Save my virus program as
Hide the program
You get the program,
double-click and the next thing you know you're getting nasty emails
from friends claiming you sent them a virus and now they're
infected. Ooops! How would you know?
Well, for one, you
should be smarter than that! You should never double-click on
anything remotely suspicious.
Next: Other Nasty Things Viruses Do