NasrinAkter

ShahidulIslam

Sheikh Mohammad

Tamim

AzizurRahman

Computer viruses are a type of software program that, like a biological virus, reproduces and spreads itself.

Some virus may display only a message on the screen, others may slow down the Pc.

They can also erase files or even format your floppy or hard disk and crash the system.

Rich Skrenta

The first computer

virus was called

‘Creeper’. It was

invented in the early

1970s.

Since then, millions

of viruses have

been invented. The

first know computer

virus was written in

1981 by a man

named Rich

Skrenta.

Accepting without reading

Opening e-mail attachments

Downloading infected software

By installing infected files

Sharing infected files through pen

drive, memory card or Bluetooth

Browsing without anti virus

Logging in to account from a link

received in e -mail, IM, or social

networking

Letters look like they are falling to the

bottom of screen

The computer system become slow

The size of available free memory

reduces

The hard disk run out of space

The computer does not boot

File got missing

File turn into short cut

Virus programs can be stored in secondary storage such as a hard drive, flash drive, floppy disk or CD and DVD disks like other programs.

Viruses can and do reside in RAM, but the virus programs are lost when the power is turned off.

Typically a computer virus is a program that can copy itself.

There are different types of viruses. They are :

Memory Resident Viruses

Boot Sector Viruses

Macro VIRUS

Multipartite Virus

Worms

Trojans

and many more…………….

These viruses fix themselves in the computer memory and get activated whenever the OS runs and infects all the files that there are opened.

HIDEOUT :- These type of virus hides in the RAM and stays there even after the malicious code is executed. It gets control over the system memory and allocate memory blocks through which it runs its own code, and executes the code when any function is executed.

TARGET :- It can corrupt files and programs that are opened closed, copied, renamed etc.

EXAMPLES :- Randex, CMJ etc.

This type of virus affects the boot sector of a hard disk. This is

a crucial part of the disk, in which information of the disk

itself is stored along with a program that makes it possible to

boot the computer from the disk. This type of virus is also

called Master Boot Sector Virus or Master Boot Record

Virus.

HIDEOUT :- It hides in the memory unit DOS accesses the

floppy disk, and whichever boot data is accessed, the virus

infects it.

EXAMPLES :- Polyboot.B, AntiEXE etc.

A macro virus is a computer virus that alters or replaces a macro, which is a set of commands used by programs to perform common actions.

For example, the “open document action” in many word processing programs relies on a macro to function, since there are several discrete steps in the process.

HIDEOUT :- These hide in documents that are shared via e-mail or networks.

EXAMPLES :- Relax, Melissa.A, Bablas, 097M/Y2K

These type of viruses spared in multiple ways

possible. It may vary in its action depending upon

the operating system installed and the presence of

certain files.

HIDEOUT:- In the initial phase, these viruses tend

to hide in the memory as the resident viruses do,

then they infect the hard disk.

EXAMPLES :- Invader, Flip etc.

A worm is a program very similar to a virus, it has the ability to self-replicate and can lead to negative effects on your system.

HIDEOUT:- This generally spread through e-mails and networks. They do not infects files or damage them, but they replicate so fast that the entire network may collapse.

EXAMPLES :- PSWBugbear.B, Lovagate.F etc.

Another unsavory breed of malicious code are trojan or trojan hores, which unlike viruses, do not reproduce by infecting other file, not do they self-replicate like worms. Infect it is a program which disguises itself as a useful program or application.

Install quality antivirus

Perform daily scans

Don't click on email links or attachments

Try to avoid downloading and installing software from the internet

Regularly update the program

Different Types of Anti-Viruses …