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6.0 AN OVERVIEW OF COMPUTER VIRUS | |
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Symptoms
of
virus
attack:
The
following
examples
may
be
indications
that
a
computer
has
been
infected
with
a
virus.
Although
these
problems
can
be
caused
by
a
non-virus
problem,
they
are
the
most
reported
symptoms
of
an
infection. 1.
Programs
take
longer
to
load
than
normal. 2.
Computer's
hard
drive
constantly
runs
out
of
free
space. 3.
The
floppy
disk
drive
or
hard
drive
runs
when
you
are
not
using
it. 4.
New
files
keep
appearing
on
the
system
and
you
don't
know
where
they
came
from. 5.
Strange
sounds
or
beeping
noises
come
from
the
computer
or
keyboard. 6.
Strange
graphics
are
displayed
on
your
computer
monitor. 7.
Files
have
strange
names
you
don't
recognize. 8.
Unable
to
access
the
hard
drive
when
booting
from
the
floppy
drive. 9.
Program
sizes
keep
changing. 10.
In
Windows
95,
32-bit
errors
keep
occurring
or
Windows
refuses
to
use
32-bit
file
or
disk
access. 11.
Conventional
memory
is
less
than
it
used
to
be
and
you
can't
explain
it. 12.
Programs
act
erratically Mode
of
Virus
attack A
virus
may
be
entered
into
a
system
by
an
unsuspecting
user
who
has
been
duped
by
the
virus
creator
(Covert
entry),
or
it
may
be
entered
directly
by
the
creator.
(Overt
entry.) A
"carrier"
program
such
as
a "pirate"
copy
of
a
commercial
package
that
has
been
tampered
with,
is
utilized
by
the
un-suspecting
user,
and
thus
enters
the
virus
code
into
the
system.
Other
types
of
carriers
could
be
programs
from
Bulletin
Boards
that
have
been
either
tampered
with
or
specifically
designed
as
viruses,
but
disguised
as
useful
programs.
There
has
even
been
a
destructive
virus
disguised
as
a "virus
protection"
program
on
a
BBS.
The
user
unknowingly
acquires
an
"infected"
disk
and
uses
it
to
boot
the
system. Examples
of
Overt
entry
into
a
computer
system.
An
individual
bent
on
harassing
the
user
or
sabotaging
the
computer
system,
modifies
an
existing
program
on
that
computer
or
copies
a
virus
program
onto
someone's
disk
during
their
absence
from
their
work
station. There
are
several
ways
you
can
get
a
virus...
Most
common
of
them
are
listed
below 1)
FLOPPY
DISKS:
"It's
10
o'clock...
do
you
know
where
your
child
is?"
Or
rather,
do
you
know
where
that
floppy
disk
has
been?
Even
the
most
trusted
of
friends
might
hand
you
a
computer
virus
on
that
disk.
And
don't
think
brand
new,
straight-out-of-the-package
software
is
always
virus
free!
2)
THE
INTERNET:
Since
this
Internet
itself
is
becoming
wildly
popular,
obviously,
so
are
attaching
viruses
to
Internet
files.
Someone
could
very
easily
post
a
desktop
theme
or
a
screen
saver
on
the
Internet,
you
download
and
run
it
(install
it),
and
you're
now
infected.
Thankfully
most
reputable
sites
scan
all
their
files
that
are
uploaded
for
viruses.
Just
browsing
the
Internet
does
not
put
you
in
danger
of
catching
a
virus:
you
must
download
AND
install
(run)
the
file
first
(again,
downloading
it
alone
will
not
infect
your
computer).
3)
EMAIL:
Here's
where
some
misconceptions
have
been
born:
"I
read
an
email
the
other
day
and
it
attached
a
virus
to
my
computer".
Sorry.
It
doesn't
work
that
way.
Only
an
.EXE
or
.COM
(or
some
similar
executable)
file
can
contain
a
virus.
SO
although
you
can't
catch
a
virus
from
the
email
itself,
be
careful
of
those
attachments.
And
watch
out
for
those
of
you
that
use
such
programs
as
Microsoft
Word
as
your
email
reader.
Many
emails
are
sent
in
a
MS
Word
format,
and,
guess
what?
Those
are
executable
attachments!
If
you're
set
up
to
AUTOMATICALLY
use
MS
Word
as
your
reader,
you
might
"execute"
the
virus
by
simply
reading
the
email.
4)
NETWORKS:
The
last
network
I
was
on
(a
large
telecommunications
company)
had
some
very
strict
rules
and
measures
in
place
to
protect
them.
But
even
with
all
that,
they're
not
immune.
The
nature
of
networks
(hundreds
or
thousands
of
computers
-
called
workstations
-
hooked
together
by
a
large
computer
-
called
a
server)
forces
systems
to
freely
pass
common
information
back
and
forth.
For
example,
one
file
might
be
used
by
several
groups
within
a
network
so
only
one
copy
is
maintained
and
all
the
computers
in
those
groups
will
have
access
to
it.
If
it's
infected,
so
then
might
ALL
the
users
in
that
group.
How
does
virus
spread? A
virus
may
reproduce
itself
by
delaying
its
attack
until
it
has
made
copies
of
itself
onto
other
disks
(Active
reproduction,)
or
it
may
depend
entirely
on
unsuspecting
users
to
make
copies
of
it
and
pass
them
around
(Passive
reproduction).
It
may
also
use
a
combination
of
these
methods. Triggering
of
virus
attack
:
Attacks
begin
upon
the
occurrence
of
a
certain
event,
such
as:
On
a
certain
date.
At
a
certain
time
of
day.
When
a
certain
job
is
run.
After
"cloning"
itself
n
times.
When
a
certain
combination
of
keystrokes
occurs.
When
the
computer
is
restarted. Distinguishing
between
virus
and
bug
:
This
can
be
a
tough
one.
With
the
publicity
surrounding
viruses,
many
people
are
ready
to
believe
that
any
strange
occurrence
while
computing
may
have
been
caused
by
a
virus,
when
it
could
simply
be
an
operational
error,
hardware
component
failure,
or
a
software
"bug."
While
most
commercial
software
developers
test
their
products
exhaustively,
there
is
always
the
possibility
that
some
combination
of
hardware;
mix
of
installed
TSR's;
user
actions;
or
slight
incompatibilities
with
"compatible"
or
"clone"
machines
or
components;
can
cause
a
problem
to
surface.
We
need
to
remember
some
key
points
here:
1.
Examine
the
probabilities
of
your
having
contacted
a
virus.
2.
Don't
just
assume
that
you've
been
attacked
by
a
virus
and
abandon
your
normal
troubleshooting
techniques
or
those
recommended
by
the
product
manufacturers.
3.
When
in
doubt
contact
your
supplier
or
the
manufacturer
for
tech
support.
4. Having an effective "Virus Protection" system installed may help you determine the cause of the problem.
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