Viruses, Worms And Trojan Horses


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Viruses, Worms And Trojan Horses

  1. 1. Viruses , Worms and Trojan horses Samuel García Cuvi
  2. 2. <ul><li>The Virus are human-made software programs created specifically to wreak havoc on personal computers and networks. The chance of contracting one of these computer viruses over the Internet has increased dramatically. In fact, unless you run anti-virus software, your computer will almost certainly become infected. Typically, you get a virus by opening infected e-mail attachments. </li></ul>
  3. 3. <ul><li>Some viruses are relatively harmless to individuals. They just attach themselves to outgoing messages or e-mail themselves to all the contacts listed in your address book. The sudden flood of e-mail overwhelms mail servers, causing the system to crash. </li></ul><ul><li>Other viruses are more destructive and may lie dormant until a certain date. Then they spring to life to do their dirty deeds. Sometimes a strange message appears on your screen, or data and programs may be modified. In the worst case, all the files on your hard drive may be wiped out. These pernicious programs start on one computer, then replicate quickly, infecting other computers around the world. </li></ul>
  4. 4. <ul><li>In 1988 a student at Cornell University sent out a virus out by accident, infecting more than 6,000 computers in minutes, nearly bringing the Internet to its knees. More recently, the &quot;I Love You&quot; virus caused over $1 billion in lost productivity as it crippled e-mail systems worldwide. Last year alone, 10,000 new viruses, worms and Trojan horses were unleashed. </li></ul>
  5. 6. Inoculate Your Computer <ul><li>If you download and run software from the Internet, or receive e-mail attachments, there's a good chance of contracting one of these digital bugs. Protect yourself by using anti-virus programs to scan your incoming e-mail attachments and alerting you if one is infected. The software also scans your hard drive periodically for viruses and deletes them. </li></ul>
  6. 7. <ul><li>The two most popular programs are from are from and Symantec. You can purchase and download the software from their websites. Both offer regular updates to handle newly discovered viruses. </li></ul><ul><li>For detailed information on specific computer viruses, visit the Symantec AntiVirus Research Center. </li></ul>
  7. 9. <ul><li>Viruses - A virus is a small piece of software that piggybacks on real programs. For example, a virus might attach itself to a program such as a spreadsheet program. Each time the spreadsheet program runs, the virus runs, too, and it has the chance to reproduce (by attaching to other programs) or wreak havoc. </li></ul><ul><li>E-mail viruses - An e-mail virus travels as an attachment to e-mail messages, and usually replicates itself by automatically mailing itself to dozens of people in the victim's e-mail address book. Some e-mail viruses don't even require a double-click -- they launch when you view the infected message in the preview pane of your e-mail software [source: Johnson]. </li></ul><ul><li>Trojan horses - A Trojan horse is simply a computer program. The program claims to do one thing (it may claim to be a game) but instead does damage when you run it (it may erase your hard disk). Trojan horses have no way to replicate automatically. </li></ul><ul><li>Worms - A worm is a small piece of software that uses computer networks and security holes to replicate itself. A copy of the worm scans the network for another machine that has a specific security hole. It copies itself to the new machine using the security hole, and then starts replicating from there, as well. </li></ul>