Instructor: Pan Shengmin

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Technology of Information Processing

• Instructor Pan Shengmin ???
• Computer Center. Kun Ming University of Science
  Technology.

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?????? CH11 Security
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Virus Protection, and Backup
Computer Viruses ?????
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What is a computer virus?

• A program that attaches itself to a file,
  reproduces itself, and spreads to other files
• A virus can perform a trigger event
• Corrupt and/or destroy data
• Display an irritating message
• Key characteristic is their ability to lurk in
  a computer for days or months quietly replicating
  themselves

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What is a computer virus?

• File virus - a virus that attaches itself to an
  application program.
• Boot sector virus - infects the system files that
  your computer uses every time you turn it on.
• Macro virus - infects a set of instructions
  called a macro

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How is a Trojan horse different from a virus?

• Appears to perform one function while actually
  doing something else
• Not a virus, but may carry a virus
• Does not replicate itself
• Another type of Trojan horse looks like a log-in
  screen
• PictureNote Trojan arrives as e-mail named
  picture.exe and then tries to steal login and
  e-mail passwords

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Whats a worm?

• A program designed to enter a computer system
  through security holes
• Usually through a network from computer to
  computer
• Does not need to be attached to a document to
  reproduce
• Mass-mailing worms
• Klez, Netsky, MyDoom, and Bagle
• Spoofed addresses ????

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What are the symptoms of a malicious code attack?

• Network traffic jam
• Denial of Service
• Browser reconfiguration
• Delete and modify files
• Access confidential information
• Performance degradation
• Disable antivirus and firewall software

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Antivirus Software How can I avoid viruses and
worms?

• Antivirus software is a set of utility programs
  that looks for and eradicates viruses, Trojan
  horses, and worms

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How does antivirus software work?

• Hackers have created viruses that can insert
  themselves into unused portions of a program
• To counterattack the work of hackers, antivirus
  software designers created software with a
  checksum - a number calculated by combining
  binary values of all bytes in a file
• Compares checksum each time you run a program

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How does antivirus software work?

• Checks for a virus signature
• A unique series of bytes used to identify a known
  virus

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When should I use antivirus software?

• All the time
• Most antivirus software allows you to specify
  what to check and when to check it

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How often should I get an update?

• New viruses and variations of old viruses are
  unleashed just about everyday
• Check Web site of antivirus software publisher
  for periodic updates
• Some software periodically reminds you to check
  for updates

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How reliable is antivirus software?

• Antivirus software is pretty reliable, but
  viruses try to get around detection
• Multi-partite viruses
• Polymorphic viruses
• Stealth viruses
• Antivirus software is not 100 reliable, but
  protection is worth the risk

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Virus Hoaxes Whats a virus hoax?

• Some viruses dont really exists
• A virus hoax arrives as an e-mail message
  containing dire warnings about a supposedly new
  virus that is on the loose
• Recommends a strategy
• Recommends forwarding the email
• Says no one has a fix for it yet
• Many cases it is a fake

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Whats a virus hoax?
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What should I do about virus hoaxes?

• Dont panic
• You can ignore a virus hoax
• You can validate the hoax by going to a reliable
  Web site that lists hoaxes and viruses

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Conclusion

• You should now be able to
• Create valid names for files and folders
• Use file management features
• Describe how a computer physically stores files
• Explain viruses, boot sector viruses, macro
  viruses, Trojan horses, worms, and Denial of
  Service attacks
• Describe how antivirus software is used
• Understand backup and restore plans
• Compare backup devices