COMPUTER VIRUSES
Computer
viruses are small software programs that are designed to spread from one
computer to another and to interfere with normal computer operation .in other words,
the computer virus spreads by itself into other executable code or documents
.the term ‘computer virus’ was first formally defined by fred cohen in 1983
computer viruses never occur naturally they are always induced by people
The
most viruses work silently making sure that the user is unaware of the infection.
It spreads from program to program and disk to disk, manipulating valuable
information or data.
Majority
of the viruses are created for sheer fun .such as, on a certain day of the month,
hearing a clicking sound every time press a key. But some viruses are written
for hateful motives like financial or professional gains or spreading panic and
terror.
INDICATION OF VIRUS INFECTION
Viruses
may cause a lot of damage to computer and network by different ways .some
indications of virus infection are:
1. The file
formats are automatically changed.
2. New files
keep appearing on the system but we do not know where they come from.
3. The file on
the computer automatically deleted.
4. The computer
unexpectedly starts rebooting.
5. The
operating system will not start at all even though you have not made any system
changes or you have not installed or removed any programs.
6. Program
takes more time than usual time to load in the memory.
7. The computer
frequently stops responding.
8. Files have
strange names that we do not recognize.
9. Inability to
access the hard drive or disk drives.
10. Installed
memory becomes less without any reason.
11. Hard disks
show no space though there is enough space.
12. Programs or
files become missing.
13. Your
computer slows down without any reason.
TYPES OF
VURUSES
There are many kinds of viruses .the level of
destruction by each virus varies widely viruses are classified as:
BOOT SECTOR
VIRUS
Boot sector virus infects the floppy disks or
hard disks. This type of virus can, at least theoretically, also exist on other
media such as CD, DVD ROM, flash drives and other removable storage. It
replaces the boot record program which is responsive for loading the operating
system in memory, copying it elsewhere on the disk or overwriting it.when the
system the system is booted with such a hard disk, it enters the memory and
whenever the computer reads or written any disk ,it will infect the files in
the disk.
PROGRAMMING
VIRUS
A program virus infects executable program files.
a file infecting virus overwrites code or inserts infected code into a
executable file , when the infected file is executed ,the virus becomes active
in the memory ,making copies of it and infection files on disk.
MACRO VIRUS
A micro virus infects data files which are
accessed more frequently by t he computer users .these infect data files, such
as word documents or excels spreadsheet, rather than programs. The infected
data files can be spared the virus very quickly. Such as overwrite each file they
infect and completely destroy the data in the file. If a macro virus has
infected these files, it has the potential to damage the document or other
computer software. When an infected file is opened, the macro virus releases a
sequence of actions that begin automatically .these actions cause damage to the
computer and its applications. These macros are usually stored as part of the
document or spreadsheet and can travel to other system when these files are
transferred to another computers.
MULTIPARTITE
VIRUS
A multipartite virus is a computer virus that
infects and spreads in multiple ways, it attacks both the boot sector and the
program files at the time for a complete cleanup, all parts of the virus must
be removed. it is also called hybrid virus.
POLYMORPHIC
VIRUS
Polymorphic viruses are complex file
infectors that can create modified versions of itself to avoid detection yet
retain the same basic routines after every infection. A polymorphic virus
changes its virus signature every time it replicates and infects a new file in
an order to keep from being detected by an antivirus program. Despite its
capabilities the polymorphic virus is not invulnerable by taking the right
steps you can protect yourself from this constantly evolving threat.
TROJAN
Trojan
is a program that hides its true intention. It is a destructive program
disguised as a game application or utility .it causes problems like killing
background system processes deletion hard drive data and corrupting file
allocation systems. When it is activated ,it caused damage although appearing
to be useful.trojan are encountered as email attachments with tempting names
that prompt people to open them.
MALWARE
Malware
and malicious software`s are programs or applications which get installed on
your computer system without your permissions and are designed to penetrate or
damage our computer system or using privilege escalation to gain remote
administrator access . In 1949 jon von Neumann`s “theory of organization of
complicated automata” introduced the idea of malware virus .it discussed how
organisms self reproduce.
SPYWARE
Spyware
is used for many purpose .usually it aims to track and sell your internet usage
data, capture your credit card or bank account information, or steal your
personal identity. Spyware is threat to businesses and individual users since
it can steal sensitive information and harm your network. Spyware is unwanted
software that infiltrates your computing device, stealing your internet usage
data and sensitive information. Program enter a computer system as part of
useful software .spyware monitor the
activities going on in your computer and can send this information
through the network this information can be misused to gain control of your
computer system remotely or to access information stored in your computer.
ADWARE
Adware
programs usually display unwanted pop us advertising a particular product or install
unnecessary applications on your computer system that can reduce you computers
productivity and efficiency. Adware is more annoying than dangerous .there will
be constant banners, in text ads that appear inside your browser window while
surfing the internet. Sometimes adware can even alter your browser settings and
cause your browser to open WebPages that you do not authorize .adware tends to
be difficult to get rid of and can required specialized virus software to
remove.
WORMS
Worms
are more complicated viruses that automatically send themselves to other
computers over a network without any human interaction or assistance worms take
control of certain software programs on a computer to spread to other computers
worms can affect data files as well as application files. Once a worm enters
your system it sort of scouts the environments looking for opportunities such
as emailing itself to everybody in your contact list. So the key differentiating
characteristic of a worm virus is that is can replicate itself, almost as
though it were a biological virus.
RETRO VIRUS
Retro
virus is another type virus which tries to attack and disable the antivirus
application running on the computer also called anti-antivirus.
MASS MAILER
VIRUS
Mass
mailer viruses search email program like MS outlook for email addresses which
are stored in the address book and replicate by emailing themselves to the
addresses stored in the address book of the email program. Besides overwhelming
servers and networks with massive volumes of emails mass mailing worms often cause
serious performance issues for infected systems.
STEP
TO INSURE SAFETY
1. Scan your
computer regularly
2. Do not open
email attachments without scanning them.
3. Install a firewall
to filter the incoming and outgoing messages
4. Adjust security
settings in your browser to ensure maximum protection
5. Backup your
files in a separate location
6. Install an
antivirus program and make sure that you keep it updated
7. Use software
from trusted sources can new software programs for viruses before installing them
8. Never use
pirated software
9. Keep a
bootable disk ready with you to access or boot the system in case of system crash due to virus infection.
10. Scan files
downloaded from the internet or those transferred through a network or removable disk.
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