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Viruses,
Trojans, and Worms
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| Introduction |
| They can be so damaging to your
computer or they can just be annoying and not so damaging.
The point is, the code is not intentionally put on your
computer so it shouldn't be there. A virus is commonly confused with worms and Trojan
Horses. They are not the same. Please read on to find out
the particular differences.
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| Virus Myths |
| To clear up any stories you may have heard over the
years, computer viruses cannot directly damage hardware,
only software is damaged. If you have ever heard someone
telling a story about the virus that fried their computer,
caught it on fire, or made their computer unable to be fixed
they are, 99% of the time, full of poo!!!!
Hardware does have its own software installed on it
to make it work. The software in the hardware however may
be damaged. That piece of hardware can "usually" be fixed
or replaced. Viruses, worms, and Trojan horses that do
these types of activities, as of
02/04/2008
, are very, very rare. |
| Who Writes
Them? |
| A computer virus is a program that was
intentionally written by a person. They write them for
varying reasons and they don't go around bragging about it
for obvious reasons. Some reasons are as follows:
Troublemakers - Think of a school bully or
Osama Bin Laden. These virus writers only do it to cause
panic and feed on the attention. They are the electronic
equals of graffiti artists, prank phone callers, etc. They
are just looking for stardom in a rather twisted way in that
no one knows who they are... Unless they get caught.
Education - These types are just learning the
ins and outs of programming. In the process, they can
become the best of the best programmers in the world.
Wasting it on such a destructive calling is ironic at least.
The Rush - These people only do it to see if
they can get away with it. They are tempting law
enforcement to find them. Also, with antivirus software
getting better and better, they have to be more creative in
keeping the their new virus undetected at least long enough
to widely spread.
Payback is Hell - Sometimes viruses or Trojan
Horses are written by disgruntled employees or others who
want to get back at someone, make a statement, or fire a
shot at another virus writing organization in an electronic
war of sorts. |
| What is a
Virus? |
| A virus is a man-made program
or piece of code that causes an unexpected, usually
negative, event. The most widely accepted view for a
malicious program to be a virus is that it must be able to replicate itself
by infecting a "host" file. The host can be any type of
file, usually an EXE or executable program. It either
replaces the file and takes its name or inserts itself into
the host file either way making it "infected". A virus is
spread by the user voluntarily downloading or copying the
file to another computer not knowing that it is infected.
Some viruses in the early days used a boot virus
method. The viruses installed themselves into the disks
boot sector, ensuring that they would be run when the user
booted the computer from the disk. Users in the early days
frequently traded disks to share software or operating
systems.
Viruses can be one of two types: Non-resident and
Resident Viruses.
Non-resident virus - This type of virus
consists of two files. A search module and a replication
module. The life of the programs moves like this. The
search module, when run, searches for the type of file it is programmed
to hunt for. When found it checks to see if it is already
infected. When it finds a fresh uninfected file it attaches
itself or replaces the file. Then it moves on to the search
mode again. Most modern, true viruses are non-resident
Resident viruses - This type loads the
replication module into memory when it is executed and
ensures that this module is executed each time the operating
system is called to perform a certain operation called a
"trigger". In general, every time your left mouse button is
clicked it infects another file. Another scenario is
every time the "F" button is pressed another file is
infected. Last, the trigger can also be a date, time,
or both. These are of course just examples. |
| What is a Worm? |
| A computer worm is a self-replicating computer
program, similar to a computer virus. A virus attaches
itself to, and becomes part of, another executable program;
however, a worm is self-contained and does not need to be
part of another program to spread.
Worms usually take advantage of security holes in
the operating system, browser, or other programs. They can
spread with little or no help from computer users.
Although, more infamous worms have spread through e-mail...
Unknowing users open a file that they think is an e-card or
game from a friend and are actually infected while the
program displays an error message or something else to
occupy the user. During this time while the users are
occupied, the worm propagates by either emailing itself to
everyone in your address book or searching for a
vulnerability on other computers on the Local and/or Wide
Access Network.
A "payload" is code designed to do more than, but
also including, spreading the worm. It might delete files
on a host system, encrypt files in a extortion attack (users
must pay to get their files back), or send documents via
e-mail.
A very common payload for worms is to install a
backdoor in the infected computer to allow the creation of a
"zombie" under control of the worm author. This means he
can use your computer or computers along with many other
"zombie computers" to attack servers that host websites
flooding them with garbage so that all of its available
internet traffic is dedicated to the reception of garbage
requests. This is known as a "DDoS" or Distributed Denial
of Service Attack. If this is directed at a for-profit
site, it is loosing money every second it is unable to
receive a request for the site.
The author can use them for his own function or he
can sell and/or rent use of them to other attackers so they
can send spam from millions of infected zombie systems,
making the spam nearly if not totally untraceable. |
| What is
a Trojan Horse? |
| Trojan horses use the disguise of a game or
harmless appearance of a picture, video or other file just
like the famous and mythical Trojan Horse given to Troy by
the Greek. Not knowing it was filled with armed warriors,
they accepted it as a gift. Even some novice computer
users will recognize an image file like .gif or .jpg but if
the file looks like this
Britney Spears Nude.jpg.exe
Would you notice the double extension in the real
world? Probably not. Windows XP and Vista, by default,
are set to hide
known file extensions. So to the user it looks like this:
Britney Spears Nude.jpg
A simple picture file? I think not. An .exe is used by
Windows as a program. When it is opened, it is run as
a program, not a picture. It will sometimes
install or drop the malicious code into your system so it is
running at all times.
A Trojan can be a type of program that may give
control of your computer to a hacker/cracker to do as he
pleases. This is also know as a "Backdoor". The cracker
can delete individual files or all your files. He can even
turn your computer into a zombie computer as described
previously on this page |
| Protection |
| If all this isn't enough for you to buy a good
anti-virus, they can be free, viruses, worms, and Trojan
horses can have a huge if not crippling effect on your
system. Do you want your computer to be reliable and work
when you want it to and how you want it to? There are
a lot of programs that claim to be an anti-viruses. A good
anti-virus will protect against the types of viruses
above.
Most anti-viruses check each program against a
library of known viruses. A good one will have Heuristic
detection or detection that just looks for code that is
deemed "suspicious". See the
Top 10
Programs to have on your Computer section in
Downloads
section of this site. This small list is just what the
title says, a list of ten programs that you should not be on
the internet without.
If you already have an anti-virus, make damn well
sure you have your virus definitions library up-to-date.
Antivirus companies like McAfee and Norton are notorious for
coming on a new system as a free perk but usually are only
90 day trials. When the trial runs out, your
protection runs out too! Download one of the
"free-forever" programs and uninstall whichever one you have
and install the one you downloaded.
- NOTE: Be sure to have one ready and downloaded to your
system before you uninstall your existing AV program.
See the
Top 10
Programs to have on your Computer section in
Downloads
section of this site.
A hundred new viruses show up daily although most
antivirus companies only put out updates once a week, unless
a fast spreading one gets "in the wild".
Viruses can also take advantage of some
vulnerabilities in your operating system and other parts of
your system
like your email program or your browser. It's always best
to have the most up-to-date operating system. If your
running Windows, go to
Microsoft's
Windows Update Site to see if you are up-to-date.
To continue this Guide, please click NEXT below.
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