Viruses,
worms
and
Trojan
Horses
are
all
malicious
programs
that
can
cause
damage
to
your
computer,
but
there
are
differences
among
the
three.
One
common
mistake
that
people
make
when
the
topic
of a
computer
virus
arises
is
to
refer
to a
worm
or
Trojan
horse
as a
virus.
While
the
words
Trojan,
worm
and
virus
are
often
used
interchangeably,
they
are
not
exactly
the
same
thing.
Viruses,
worms
and
Trojan
Horses
are
all
malicious
programs
that
can
cause
damage
to
your
computer,
but
there
are
differences
among
the
three,
and
knowing
those
differences
can
help
you
better
protect
your
computer
from
their
often
damaging
effects.
What
Is a
Virus?
A
computer
virus
attaches
itself
to a
program
or
file
enabling
it
to
spread
from
one
computer
to
another,
leaving
infections
as
it
travels.
Like
a
human
virus,
a
computer
virus
can
range
in
severity:
some
may
cause
only
mildly
annoying
effects
while
others
can
damage
your
hardware,
software
or
files.
Almost
all
viruses
are
attached
to
an
executable
file,
which
means
the
virus
may
exist
on
your
computer
but
it
actually
cannot
infect
your
computer
unless
you
run
or
open
the
malicious
program.
It
is
important
to
note
that
a
virus
cannot
be
spread
without
a
human
action,
(such
as
running
an
infected
program)
to
keep
it
going. Because
a
virus
is
spread
by
human
action
people
will
unknowingly
continue
the
spread
of a
computer
virus
by
sharing
infecting
files
or
sending
emails
with
viruses
as
attachments
in
the
email.
What
Is a
Worm?
A
worm
is
similar
to a
virus
by
design
and
is
considered
to
be a
sub-class
of a
virus.
Worms
spread
from
computer
to
computer,
but
unlike
a
virus,
it
has
the
capability
to
travel
without
any
human
action.
A
worm
takes
advantage
of
file
or
information
transport
features
on
your
system,
which
is
what
allows
it
to
travel
unaided.
The
biggest
danger
with
a
worm
is
its
capability
to
replicate
itself
on
your
system,
so
rather
than
your
computer
sending
out
a
single
worm,
it
could
send
out
hundreds
or
thousands
of
copies
of
itself,
creating
a
huge
devastating
effect.
One
example
would
be
for
a
worm
to
send
a
copy
of
itself
to
everyone
listed
in
your
e-mail
address
book.
Then,
the
worm
replicates
and
sends
itself
out
to
everyone
listed
in
each
of
the
receiver's
address
book,
and
the
manifest
continues
on
down
the
line. Due
to
the
copying
nature
of a
worm
and
its
capability
to
travel
across
networks
the
end
result
in
most
cases
is
that
the
worm
consumes
too
much
system
memory
(or
network
bandwidth),
causing
Web
servers,
network
servers
and
individual
computers
to
stop
responding.
In
recent
worm
attacks
such
as
the
much-talked-about
Blaster
Worm,
the
worm
has
been
designed
to
tunnel
into
your
system
and
allow
malicious
users
to
control
your
computer
remotely.
What
Is a
Trojan
horse?
A
Trojan
Horse
is
full
of
as
much
trickery
as
the
mythological
Trojan
Horse
it
was
named
after.
The
Trojan
Horse,
at
first
glance
will
appear
to
be
useful
software
but
will
actually
do
damage
once
installed
or
run
on
your
computer.
Those
on
the
receiving
end
of a
Trojan
Horse
are
usually
tricked
into
opening
them
because
they
appear
to
be
receiving
legitimate
software
or
files
from
a
legitimate
source.
When
a
Trojan
is
activated
on
your
computer,
the
results
can
vary.
Some
Trojans
are
designed
to
be
more
annoying
than
malicious
(like
changing
your
desktop,
adding
silly
active
desktop
icons)
or
they
can
cause
serious
damage
by
deleting
files
and
destroying
information
on
your
system.
Trojans
are
also
known
to
create
a
backdoor
on
your
computer
that
gives
malicious
users
access
to
your
system,
possibly
allowing
confidential
or
personal
information
to
be
compromised.
Unlike
viruses
and
worms,
Trojans
do
not
reproduce
by
infecting
other
files
nor
do
they
self-replicate.
What
Are
Blended
Threats?
- Added into the mix, we also have what is called a blended threat. A blended threat is a more sophisticated attack that bundles some of the worst aspects of viruses, worms, Trojan horses and malicious code into one single threat. Blended threats can use server and Internet vulnerabilities to initiate, then transmit and also spread an attack. Characteristics of blended threats are that they cause harm to the infected system or network, they propagates using multiple methods, the attack can come from multiple points, and blended threats also exploit vulnerabilities. To be considered a blended thread, the attack would normally serve to transport multiple attacks in one payload. For example it wouldn't just launch a DoS (denial of service) attack — it would also, for example, install a backdoor and maybe even damage a local system in one shot. Additionally, blended threats are designed to use multiple modes of transport. So, while a worm may travel and spread through e-mail, a single blended threat could use multiple routes including e-mail, IRC and file-sharing sharing networks. Lastly, rather than a specific attack on predetermined .exe files, a blended thread could do multiple malicious acts, like modify your exe files, HTML files and registry keys at the same time — basically it can cause damage within several areas of your network at one time. Blended threats are considered to be the worst risk to security since the inception of viruses, as most blended threats also require no human intervention to propagate.
Tips to Combat Viruses, Worms and Trojan Horses on Your Computer:
Keep The Operating System Updated The first step in protecting your computer from any malicious there is to ensure that your operating system (OS) is up-to-date. This is essential if you are running a Microsoft Windows OS.
- Secondly, you need to have anti-virus software installed on your system and ensure you download updates frequently to ensure your software has the latest fixes for new viruses, worms, and Trojan horses.
- Additionally, you want to make sure your anti-virus program has the capability to scan e-mail and files as they are downloaded from the Internet, and you also need to run full disk scans periodically. This will help prevent malicious programs from even reaching your computer.
Use a Firewall
You should also install a firewall. A firewall is a system that prevents unauthorized use and access to your computer. A firewall can be either hardware or software. Hardware firewalls provide a strong degree of protection from most forms of attack coming from the outside world and can be purchased as a stand-alone product or in broadband routers. Unfortunately, when battling viruses, worms and Trojans, a hardware firewall may be less effective than a software firewall, as it could possibly ignore embedded worms in out going e-mails and see this as regular network traffic. For individual home users, the most popular firewall choice is a software firewall. A good software firewall will protect your computer from outside attempts to control or gain access your computer, and usually provides additional protection against the most common Trojan programs or e-mail worms. The downside to software firewalls is that they will only protect the computer they are installed on, not a network. It is important to remember that on its own a firewall is not going to rid you of your computer virus problems, but when used in conjunction with regular operating system updates and a good anti-virus scanning software, it will add some extra security and protection for your computer or network.
Did
You
Know...
CodeRed,
a
blended
threat,
launched
DoS
attacks,
defaced
Web
servers,
and
its
variant,
CodeRed
II,
left
Trojan
horses
behind
for
later
execution.
CodeRed
was
processed
in
memory
—
not
on a
hard
disk
—
allowing
it
to
slip
past
some
anti-virus
products.
Computer
Economics
has
estimated
the
worldwide
cost
of
CodeRed
at
$2.62
billion
dollars.
Key
Terms
To
Understanding
Computer
Viruses:
Virus:
A
program
or
piece
of
code
that
is
loaded
onto
your
computer
without
your
knowledge
and
runs
against
your
wishes.
Trojan
Horse:
A
destructive
program
that
masquerades
as a
benign
application.
Unlike
viruses,
Trojan
horses
do
not
replicate
themselves.
Worm:
A
program
or
algorithm
that
replicates
itself
over
a
computer
network
and
usually
performs
malicious
actions.
Blended
Threat:
Blended
threats
combine
the
characteristics
of
viruses,
worms,
Trojan
Horses,
and
malicious
code
with
server
and
Internet
vulnerabilities.
Antivirus
program:
A
utility
that
searches
a
hard
disk
for
viruses
and
removes
any
that
are
found.
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