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Oracle Tips by Burleson |
Web Stalkers
Chapter 12 - Virus Attacks
What Is a Virus?
What kinds of things will a virus do once it
begins to execute? Amazingly, there are people who go to the trouble
to write harmless viruses. One example is a virus that will
generate an animated cartoon image with a funny message. People who
write these viruses are sometimes motivated by curiosity. They may
just want to see how far it will spread.
Other viruses are more malevolent and are
written with the destructive intensions. One kind of virus,
sometimes called Spyware, will gather information and e-mail it off
to whatever e-mail address is specified by the virus’ author. This
can all be done below the radar, and the computer user may never
know it is happening.
Other dangerous viruses will try to damage and
delete files. Word processing, spreadsheet and database files,
containing vital and sometimes irreplaceable information can be
lost, with devastating results. The virus can also target files
that are necessary for a machine to run properly. If these files
are damaged, the computer might stop working altogether.
An example of a virus of this type is a
variation of the well-known Melissa virus, also known as W97M/Assilem.A.
This little gem was written specifically to target Word97 normal.dot
files. Once the infection is established, any Word document that is
opened will become infected and capable of transferring the virus to
still more machines. Since Word documents are often sent as email
attachments, the virus had a ready-made mobility.
However, there is a limiting factor to this
scheme. The user must manually send the infected file in an
e-mail. Of course, they will not know the file is infected when
they send it. It is possible that the virus will have to wait a
very long time for a file to which it is attached to be sent. It
may, in fact, never be sent. In this case, the virus stays on the
machine and is not spread to others. This makes such viruses much
slower spreading, if not less damaging.
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