ITIS 1210 Introduction to Web-Based Information Systems Chapter 47 How Viruses Work

Introduction  Downloading files exposes you to viruses  Written for specific types of computers  Programs that  Delete data  Erase programs  Wipe hard drives  Install spyware  Display messages

Introduction  Get viruses from  Downloaded files & programs   Commercial products  Web sites  Viruses  Infect your computer  Replicate themselves  Distribute themselves  Inflict damage

Introduction  Attack four parts of your computer  Executable programs  File directory system  Boot & system areas  Data  Two major types  Trojan horses  Worms

Introduction  Trojan horse  Appears to be something else  Worm  Designed to infect networks  Robert Morris  Melissa

Robert Tappan Morris  Released in 1988  Grad student at Cornell  1 st computer worm on Internet  Intended to gauge the size of the Internet  Design flaw caused it to replicate too much  Infected thousands of computers  $ million in damages estimated

Robert Tappan Morris  1989 – Indicted under the Computer Fraud and Abuse Act  1 st person  1990 – Convicted  Three years probation  400 hours community service  $10,050 fine  Tenured professor at MIT

Melissa  David L. Smith  Released March 1999  Aberdeen Township, NJ  Posted an infected document to alt.sex Usenet newsgroup  Passwords to 80 Internet porn sites  Named after a lap dancer he knew in Florida

Melissa  Spread via  Forwards itself to 1 st 50 addresses in Outlook  Inserted Simpsons references into documents  Cost more than $80,000,000 in damages  Microsoft, Intel, Lockheed-Martin shut down  Originally sentenced to 10 years  Served 20 months, $5,000 fine  Worked for FBI

Examining FAT Disks  Allocate 1 cluster (8 sectors)  Record data  Write End-of-File marker …… Data Slack Cluster (an indivisible unit) Allocated to a file Unallocated