COMPUTER VIRUS A Computer virus is A software

COMPUTER VIRUS

A Computer virus is A software program with The ability to reproduce Itself. It may or may not amage data or other program progra

Properties of virus A set of instructions Ability to infect other programs Ability to hide itself Ability to replicate Ability to do harm

SYPTOMS OF VIRUS THE MAIN SYMOTOMS ARE: • DATA LOSS • REDUCE HARDWARE SPACE • PROGRAM CRASHES • UNUSUAL MESSAGES • REDUCED COMPUTER PERFOMANCE

SOURCES OF VIRUS THE MAIN SOURCES OF VIRUS ARE THE FOLLOWING: q. FLOPPY DISKS q. CD ROMS q. USB DRIVES q. INTERNET: SPREAD VIRUS WHEN DOWNLOADING FILES, OPENING SOME SITES. ETC. SOME E MAILS HAVE VIRUS ATTACHEMENT.

ACTIVITIES BY A VIRUS • INFECTS EXECUTABLE PROGRAM LIKE SPREADSHEET, PROCESSORS OR OPERATING SYSTEM FILES • INFECTS BOOT SYSTEM FILES WHICH IS REQUIRED TO START A PROGRAM. • INFECTS FILE ATTACHED TO EMAIL MESSAGE. INFECTS DATA DISK THAT IS USED TO EXCHANGE PROGRAMS.

CLASSIFICATION OF VIRUSES • COMPUTER VIRUSES CAN BE CLASSIFIED INTO THREE: TIME BOMBS , TROJAN HORSES AND WORMS. BOMBS AND HORSES CANNOT REPLICATE WHERE ELSE ALL OTHE VIRUSES REPLICATE. THESE ARE FURTHER DIVIDED INTO GROUPS. • BOOT SECTOR VIRUS • FILE INFECTION VIRUSE • DOS SYSTEM INFECTION VIRUSES

• IT RESIDES INSIDE THE BOOT SECTOR OF A FLOPPY OR HARD DISK. IT COPIES THE BOOT PROGRAM TO A DIFFERENT PLACE. • EX: JOSHI, (C) BRAIN, BFD, STONE. ETC.

DOS SYSTEM INFECTION VIRUS THIS AFFECTS THE DOS SYSTEM FILE LIKE MSDOS. SYS , IO. SYS AND COMMAND. COM. THEY MOVE INTO THE MEMORY BEFORE ANY OTHER PROGRAM IS LOADED.

HOW DOES A VIRUS ATTACK? • ALL VIRUSES HAVE FOUR PHASE IN THEIR LIFE EXECUTION CYCLE. THEY ARE: • DORMANCY • PROPAGATION • TRIGGERING • ACTION

DORMANCY IN THIS PHASE THE VIRUS DOE NOTHING. IT IS USED BY THE CREATOR TO MAKE A SENSE OF TRUST IN THE USER.

PROPAGATION THIS PHASE IS NECCESARY FOR A PROGRAM TO BE VIRUS. DURING THIS TIME THE VIRUS MULTIPLY ITSELF AND COPIES ITSELF TO PROGRAMS MEMORY OR STORAGE MEDIA.

TRIGGERING IT IS ACTIVATED BY SOME OCCURANCE OF A PARTICULAR DATE OR A GIVEN NUMBER OF REPLICATIONS OR ANY LOGICAL CONDITIONS. THE BEST EXAMPLE OF THIS IS 13 FRIDAY VIRUS. THE VIRUS GETS ACTIVATED ON THIS DAY.

ACTION THIS PHASE IS MEANT FOR AN ACTION PERFOMED BY A VIRUS. IT COULD BE PRANKISH SUCH AS DISPLAYING A MESSAGE OR BOUNCING SOME DOTS ON THE SCREEN. IT MAY ALSO DAMAGE THE DATA OR PROGRAMS ON YOUR DISK.

Thank you Done by sangeetha