Computer threats Malware, Spyware, Virus, Worm , Bot , Backdoor

Virus – this is a term that used to be generic.
Any bad software used to be a virus;
however, we use the term “malware” now.
We use the word “virus” to describe a
program that self-replicates after hooking
itself onto something running in Windows®.
Worm – a worm is another kind of self-
replicating program but generally doesn’t
hook itself onto a Windows process. Worms
generally are little programs that run in the
background of your system.
Trojan – software that you thought was going
to be one thing, but turns out to be
something bad. Named for the fabled “Trojan
Horse” that appeared to be a gift but in fact
carried a dangerous payload.
Drive-by download – this is probably the
most popular way to get something nasty
into your computer. Most of the time, it
comes from visiting a bad web page. That
web page exploits a weakness in your
browser and causes your system to become
infected.
Malware Actions
Malware:
This is a big catchall phrase that covers all
sorts of software with nasty intent. Not
buggy software, not programs you don’t like,
but software which is specifically written
with the intent to harm.
Once malware is in your computer, it can do
many things. Sometimes it’s only trying to
replicate itself with no harm to anyone, other
times it’s capable of doing very nasty things.
Adware – not truly malware and almost
never delivered using one of the methods
above. Adware is software that uses some
form of advertising delivery system.
Sometimes the way that advertisements are
delivered can be deceptive in that they track
or reveal more information about you than
you would like. Most of the time, you agree
to the adware tracking you when you install
the software that it comes with. Generally, it
can be removed by uninstalling the software
it was attached to.
Spyware – software that monitors your
computer and reveals collected information
to an interested party. This can be benign
when it tracks what webpages you visit; or it
can be incredibly invasive when it monitors
everything you do with your mouse and
keyboard.
Ransomware – lately a very popular way for
Internet criminals to make money. This
malware alters your system in such a way
that you’re unable to get into it normally. It
will then display some kind of screen that
demands some form of payment to have the
computer unlocked. Access to your computer
is literally ransomed by the cyber-criminal.
Scareware – software that appears to be
something legit (usually masquerading as
some tool to help fix your computer) but
when it runs it tells you that your system is
either infected or broken in some way. This
message is generally delivered in a manner
that is meant to frighten you into doing
something. The software claims to be able to
fix your problems if you pay them.
Scareware is also referred to as “rogue”
software – like rogue antivirus.
Bots
"Bot" is derived from the word "robot" and
is an automated process that interacts with
other network services. Bots often automate
tasks and provide information or services
that would otherwise be conducted by a
human being. A typical use of bots is to
gather information (such as web crawlers),
or interact automatically with instant
messaging (IM), Internet Relay Chat (IRC), or
other web interfaces. They may also be used
to interact dynamically with websites.
Bots can be used for either good or
malicious intent. A malicious bot is self-
propagating malware designed to infect a
host and connect back to a central server or
servers that act as a command and control
(C&C) center for an entire network of
compromised devices, or "botnet." With a
botnet, attackers can launch broad-based,
"remote-control," flood-type attacks against
their target(s). In addition to the worm-like
ability to self-propagate, bots can include the
ability to log keystrokes, gather passwords,
capture and analyze packets, gather financial
information, launch DoS attacks, relay spam,
and open back doors on the infected host.
Bots have all the advantages of worms, but
are generally much more versatile in their
infection vector, and are often modified
within hours of publication of a new exploit.
They have been known to exploit back doors
opened by worms and viruses, which allows
them to access networks that have good
perimeter control. Bots rarely announce
their presence with high scan rates, which
damage network infrastructure; instead they
infect networks in a way that escapes
immediate notice.
Exploit
An exploit is a piece of software, a
command, or a methodology that attacks a
particular security vulnerability. Exploits are
not always malicious in intent—they are
sometimes used only as a way of
demonstrating that a vulnerability exists.
However, they are a common component of
malware.
Back Door
A back door is an undocumented way of
accessing a system, bypassing the normal
authentication mechanisms. Some back doors
are placed in the software by the original
programmer and others are placed on
systems through a system compromise, such
as a virus or worm. Usually, attackers use
back doors for easier and continued access
to a system after it has been compromised.