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Chapter Overview

Chapter Overview. Chapter 6: Computer and Network Security. Introduction Viruses, worms, and Trojan horses Phreaks and hackers Denial-of-service attacks. Introduction. Computers getting faster and less expensive Utility of computers increasing Email Web surfing Shopping

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Chapter Overview

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  1. Chapter Overview Chapter 6: Computer and Network Security • Introduction • Viruses, worms, and Trojan horses • Phreaks and hackers • Denial-of-service attacks

  2. Introduction • Computers getting faster and less expensive • Utility of computers increasing • Email • Web surfing • Shopping • Managing personal information • Increasing use of computers growing importance of computer security

  3. Viruses (1/2) • Virus: piece of self-replicating code embedded within another program (host) • Viruses associated with program files • Hard disks, floppy disks, CD-ROMS • Email attachments • How viruses spread • Diskettes or CDs • Email • Files downloaded from Internet

  4. Viruses (2/2) • Well-known viruses • Brain • Michelangelo • Melissa • Love Bug • Viruses today • Commercial antivirus software • Few people keep up-to-date

  5. Worms • Worm • Self-contained program • Spreads through a computer network • Exploits security holes in networked computers • Famous worms • WANK • Code Red • Sapphire (Slammer) • Blaster • Sasser

  6. Trojan Horses • Trojan horse: program with benign capability that masks a sinister purpose • Remote access Trojan: Trojan horse that gives attack access to victim’s computer • Back Orifice • SubSeven • RAT servers often found within files downloaded from erotica/porn Usenet sites

  7. Bot Networks • Bot: A software program that responds to commands from a program on another computer • Some bots support legitimate activities • Internet Relay Chat • Multiplayer Internet games • Other bots support illegitimate activities • Distributing spam • Collecting person information for ID theft • Distributed denial-of-service attacks

  8. Defensive Measures • System administrators play key role • Authorization: determining that a user has permission to perform a particular action • Authentication: determining that people are who they claim to be • Firewall: a computer monitoring packets entering and leaving a local area network

  9. Hackers (1/2) • Original meaning • Explorer • Risk-taker • Technical virtuoso • Hacker ethic • Hands-on imperative • Free exchange of information • Mistrust of authority • Value skill above all else • Optimistic view of technology

  10. Hackers (2/2) • Meaning of “hacker” changed • Movie WarGames • Teenagers accessing corporate or government computers • Dumpster diving • Social engineering • Malicious acts • Destroying databases • Stealing confidential personal information

  11. Phone Phreaking • Phone phreak: someone who manipulates phone system to make free calls • Most popular methods • Steal long-distance telephone access codes • Guess long-distance telephone access codes • Use a “blue box” to get free access to long-distance lines • Access codes posted on “pirate boards”

  12. Penalties for Hacking • Examples of illegal activities • Accessing without authorization any Internet computer • Transmitting a virus or worm • Trafficking in computer passwords • Intercepting a telephone conversation, email, or any other data transmission • Accessing stored email messages without authorization • Adopting another identity to carry out an illegal activity • Maximum penalty: 20 years in prison + $250,000 fine

  13. Denial-of-Service AttacksDoS • Denial-of-service attack: an intentional action designed to prevent legitimate users from making use of a computer service • Goal of attack: disrupt a server’s ability to respond to its clients • About 4,000 Web sites attacked each week • Asymmetrical attack that may prove popular with terrorists

  14. Attacks that Consume Scarce Resources • SYN flood attack A SYN flood is a form of denial-of-service attack in which an attacker sends a succession of SYN requests to a target's system in an attempt to consume enough server resources to make the system unresponsive to legitimate traffic. • Smurf attack The Smurf attack is a way of generating significant computer network traffic on a victim network. This is a type of denial-of-service attack that floods a system via spoofed broadcast ping messages. • Fill target computer’s hard disk • Email bombing • Worm • Break-in followed by file copying

  15. Defensive Measures • Physical security of server • Benchmarking • Disk quota systems • Disabling unused network services • Turning off routers’ amplifier network capability

  16. Distributed Denial-of-Service AttacksDDoS • Attacker gains access to thousands of computers • Launches simultaneous attack on target servers • Defensive measures • Secure computers to prevent hijackings • Check for forged IP addresses

  17. SATAN • Security Administrator Tool for Analyzing Networks (SATAN) • Allows administrators to test their systems • Could be used to probe other computers • Critics worried SATAN would turn unskilled teenagers into hackersThat never happened

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