The document discusses computer viruses, how they spread and affect systems. It describes how the first virus, called "Creeper, was created in 1970s and outlines common ways viruses enter systems like through email attachments. Different virus types are outlined like memory resident viruses, boot sector viruses and macro viruses that hide in various parts of the system. Symptoms of virus infection and basic prevention tips are provided.

2. Nasrin
Akter
Shahidul
Islam
Sheikh
Mohammad
Tamim
Azizur
Rahman

3.  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.

4. 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.

5.  Accepting without reading
 Opening e-mail attachments
 Downloading infected software
 By installing infected files

6.  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

7.  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

8. 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.

9. There are different types of viruses. They are :
 Memory Resident Viruses
 Boot Sector Viruses
 Macro VIRUS
 Multipartite Virus
 Worms
 Trojans
and many more…………….

10. 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.

11. 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.

12. 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

13. 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.

14. 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.

15. 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.

16.  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

17. Different Types of Anti-Viruses …