11/06/2012 08:21:00 pm
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Computer VIRUS i.e Vital Information Resource Under Seize are considered as very first form of computer threats. Computer VIRUS usually replicate themselves, damage your files and are also able to distribute themselves on network. Virus is usually a executable file. It may be different or same for different Operating system.
Most of the times virus disguise themselves as system files so that they can avoid detection. Their detection prevention mechanism is so strong that a common user can never figure out, whether a file is virus or just another system file or data file.
Most of the times virus disguise themselves as system files so that they can avoid detection. Their detection prevention mechanism is so strong that a common user can never figure out, whether a file is virus or just another system file or data file.
Viruses can be classified as follows:
Boot Sector Virus:- Boot sector viruses or MBR Viruses
are responsible for damaging boot records of a system. When executed
they copy themselves in boot sector and load themselves every time the
system starts.(MBR i.e Master Boot Record is the record stored on hard
disk or bootable CD which stores information about startup of system. In
other words files stored in MBR are the very first thing that is loaded
in memory for execution.). Examples of boot sector virus are Form, Michelangelo, Stone, Disk Killer etc.
File Virus:- File virus, as its name suggests are made to damage your files. They can also damage your program files and hence also known as Program Virus. They usually infect executable files, system files and driver files. Example of file virus are Sunday, Cascade etc.
Multipartite Virus:- Multipartite virus are hybrid viruses. They have properties of both boot sector and file virus.
So they are more dangerous than first two mentioned above because they
not only infect boot sector but also system files. Common examples are
Invader, Flip and Tequila.
Stealth Viruses:-Stealth viruses
are able to hide themselves to avoid detection They can store
themselves in memory during scanning by Anti-Virus Programs and get
restored when scanning is over. Due to their this type of stealthy
nature they are named as Stealth Virus. They are so well
programmed that they can even hide themselves inside other files without
increasing size of file. This is also one of the mechanism they use to
survive from Anti-Virus Programs. These viruses are one of the most difficult viruses to detect. Common examples are Frodo, Joshi, Whale etc.
Polymorphic Viruses:-
A virus that can encrypt its code in different ways so that it appears
differently in each infection. These viruses are more difficult to
detect. Common examples are Involuntary, Simulate, Cascade, Pheonix etc.
Macro Viruses:
Virus that infects the macros within a document or template. When you
open a word processing or spreadsheet document, the macro virus is
activated and it infects the Normal template (Normal.dot)-a general
purpose file that stores default document formatting settings. Every
document you open refers to the Normal template, and hence gets infected
with the macro virus. Since this virus attaches itself to documents,
the infection can spread if such documents are opened on other
computers. The very dangerous thing about these viruses is they are not
platform specific that means a code once written can infect any OS.
Common examples are DMV, Word Concept etc.
Active-X Virus: Active-X viruses
are under emerging stage. They are usually executed on victims PC via
web browser. The JAVA scripts, Perl scripts, Flash scripts enabled on
victim's PC without any Firewall, Anti-Virus, Internet Security Suite
can easily obtain access to PC. Keeping Video and Audio plug ins ready
without protection can bring Active-X Virus to your party.
How you can keep your computer virus free:
Following are some simple tips that will help you keep your computer safe from viruses,
1.Never open any pen-drive by double clicking on it open it by address pane from my computer.
2.Always keep your auto play option off.
This
is how you can do it, for windows xp from start menu, click on run
command write "gpeit.msc" and press enter “group policy editor” will
open in front of you, now navigate
user
configuration-->administrative templates-->system, find out "turn
off autoplay" and make it enabled. For vista and 7 you can directly
turn it off by control panel.
3.If
you are buying a computer make sure you buy only original OS for it, a
legal system gets updated and also gets support from vendors. A pirated
copy of OS may itself contain any malicious code that may even help viruses to stay hidden from anti-virus.
4.Always keep your system and anti-virus updated and use firewall while on Internet.
5.Always keep hidden folders option and hide file types disabled, to do this open any instance of "explorer.exe" goto
tools-->folder options-->view
now disable options "do not show hidden files and folders" and "hide extensions of known files". This will help you keep eye on suspicious files and folders.
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