A
computer virus is
software with the ability to self-replicate
and attach itself to other executable programs.
The
behavior is comparable to its biological counterpart.
Computer viruses can also be contagious
(might spread on or even beyond the infected computer),
exhibit symptoms (the presence of malicious code and its
magnitude) and involve a recovery period with possible
long-term effects (difficulty in removal and loss of data).
Common Types of Viruses
· ActiveX
viruses infect
only browsers
that support ActiveX.
· Boot
sector viruses infect
a particular sector on
storage media that is reserved for data needed to
boot
.
up a computer.
· Java
viruses exploit
vulnerabilities in outdated versions of the Java Runtime
Environment.
· Macro
viruses can
occur in all file types that permit storage of
document-related macros.
· Script
viruses spread
by exploiting script languages, including cross-platform
languages.
· File
infector viruses infect
executable programs.
Proliferation
Viruses can spread by attaching themselves to many types of
files as soon as these files are executed, copied or sent.
Payload
Some
computer viruses are programmed to include a payload. This
payload can either display propaganda or images, or else
destroy files, reformat your hard drive or cause other
damage.
If the
virus is not programmed to do damage, it can still cause
problems by blocking hard disk space and RAM, weakening the
overall performance of your computer. Virus attacks are
becoming more and more the norm and occurring with greater
frequency than in the past, often with disastrous
consequences.
Growing
Proliferation
One cause
for the rise in virus attacks is the sharp rise in the
number of networked
computers,
especially related to Internet usage. The larger the number
of shared files, the greater the risk of a virus infection.
Besides the
rising number of opportunities for viruses to penetrate an
organization, another reason for the rise in attacks is new
types of viruses. These include macro viruses and portable
executable viruses (PE viruses), which can spread very
quickly through shared documents and e-mails or e-mail
attachments.
Worms
A
computer worm
is an autonomous program or constellation of programs that
distributes fully functional whole or partial copies of
itself to other computers.
The unique
feature of a
computer worm is its ability to exploit
every feasible method of spreading to achieve its objective
of maximum possible proliferation.
Worms
are specialists in spreading and reproducing. They
consistently exploit all known vulnerabilities, including
people, to penetrate barriers that seem to be impenetrable
to normal viruses. A worm does not have a payload of its own
but is often used as a transport mechanism for viruses that
ride piggyback and immediately start their work.
Proliferation
Worms
spread through various methods, including:
· E-mail
with attachment
- The trick here is for a worm to search through the e-mail
address book of an infected computer and automatically send
e-mails to all available addresses under the owner's name -
with itself as an attachment.
· A
network
connection - as is present during internet usage, for
example - is used by some worms to infiltrate connected
computers without any further action required by exploiting
vulnerabilities.
· Worms
can also be spread by all other methods common to
malware. The
danger, as already mentioned, is that worms exploit all
opportunities simultaneously. |
