WHAT IS A "VIRUS"?

Computer viruses are called viruses because they share someof the traits of biological viruses.

A computer virus passes from computer to computer like a biological virus passes from person to person.

BIOLOGICAL VIRUSES • A biological virus is not a living thing• A virus is a fragment of DNA inside a protective jacket• A biological virus must inject its DNA into a cell

COMPUTER VIRUSES

• A computer virus must piggyback on top of some other program or document in order to get executed• Once it is running, it is then able to infect other programs or documents

WHAT IS A "VIRUS"?

VIRUS HISTORY

Traditional computer viruses were first widely seen in the late 1980sViruses took advantage of these three facts to create the first self-

replicating programs!

FIRST FACTOR Spread of personal computers

SECOND FACTORUse of computer "bulletin boards"

THIRD FACTORThe floppy disk

1. FILE INFECTORS VIRUSESa. Embedded in programb. Runs when program gets executedc. Loads in memoryd. Cycle continues through sharing files

2. BOOT-SECTOR VIRUSESa. Load viruses into memory b. Infect the boot sector on floppy disks and hard disks

3. MACRO VIRUSESa. Infects data filesb. Executed in embedded scriptsc. Inserts copies of itself into other documentsd. Spreads by sharing data files

CLASSES OF VIRUSES

1. Large size of today's programs (executable)

2. Operating systems now protect the boot sector

EXECUTABLE AND BOOT SECTOR VIRUSES ARE NOT VERY THREATENING ANY MORE

CLASSES OF VIRUSES

E-MAIL VIRUSES

E-MAIL VIRUSES ARE THE LATEST INVENTION

1. Melissa Virus (March 1999)a. Embedded into Word documentb. When opened, sent to first 50 email addresses in address bookc. Included a friendly note making it look harmlessd. If opened by any of the recipients, sent to another 50 addresses of the current recipient

1. The ILOVEYOU Virus (May 2000)a. Attachment is a piece of codeb. When executed, sent itself to everyone in the address bookc. Corrupted files

ORIGINS

THREE REASONS PEOPLE CREATE VIRUSES

1. The same psychology that drives vandals and arsonists

2. The thrill of watching things destroyed

3. Bragging rights, or the thrill of doing it

FIGHTING VIRUSES

ANTIVIRUS PROGRAMS

- Norton Antivirus (Symantec)

- VirusScan (McAfee)

- F-Secure Anti-Virus (F-Secure)

No anti-viruses guarantee 100 percent protection from viruses!!!

1 I-Worm.Klez 96.49%2 Win95.CIH 0.84%3 I-Worm.BadtransII 0.52%4 I-Worm.Hybris 0.30%5 Trojan.PSW.Delf 0.24%6 I-Worm.Sircam 0.21%7 Win32.Elkern.c 0.16%8 Macro.Word.Cap 0.13%9 Win32.FunLove 0.09%10 I-Worm.Magistr 0.07%

Position Name Number of occurrences

STATISTICS

STATISTICS

NUMBER OF INFECTED FILES BY COUNTRY, WITHIN THE LAST 30 DAYS

0-100

101-1000

1001-10,000

10,001-100,000

100,001+