Internet security

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  • 1. Security Awareness Chapter 3 Internet Security
  • 2. Objectives After completing this chapter, you should be able to do the following: •Explain how the World Wide Web and e-mail work •List the different types of Internet attacks •Explain the defenses used to repel Internet attacksSecurity Awareness, 3rd Edition 2
  • 3. How the Internet Works • Internet – Worldwide set of interconnected computers, servers, and networks – Not owned or regulated by any organization or government entity – Computers loosely cooperate to make the Internet a global information resource Security Awareness, 3rd Edition 3
  • 4. The World Wide Web • World Wide Web (WWW) – Better known as the Web – Internet server computers that provide online information in a specific format • Hypertext Markup Language (HTML) – Allows Web authors to combine text, graphic images, audio, video, and hyperlinks • Web browser – Displays the words, pictures, and other elements on a user’s screen Security Awareness, 3rd Edition 4
  • 5. The World Wide Web (cont’d.) Figure 3-1 How a browser displays HTML codeSecurity Awareness, 3rd Edition 5
  • 6. The World Wide Web (cont’d.) • Hypertext Transport Protocol (HTTP) – Standards or protocols used by Web servers to distribute HTML documents – Transmission Control Protocol/Internet Protocol (TCP/IP) • Port number – Identifies the program or service that is being requested – Port 80 • Standard port for HTTP transmissionsSecurity Awareness, 3rd Edition 6
  • 7. The World Wide Web (cont’d.) • Transfer-and-store process – Entire document is transferred and then stored on the local computer before the browser displays it – Creates opportunities for sending different types of malicious code to the user’s computerSecurity Awareness, 3rd Edition 7
  • 8. The World Wide Web (cont’d.)Figure 3-2 HTML document sent to browserCourse Technology/Cengage Learning Security Awareness, 3rd Edition 8
  • 9. E-Mail • Number of e-mail messages sent each day to be over 210 billion – More than 2 million every second • Simple Mail Transfer Protocol (SMTP) – Handles outgoing mail • Post Office Protocol (POP or POP3) – Responsible for incoming mail • Example of how e-mail works Security Awareness, 3rd Edition 9
  • 10. E-Mail (cont’d.) Figure 3-3 E-mail transport Course Technology/Cengage LearningSecurity Awareness, 3rd Edition 10
  • 11. E-Mail (cont’d.) • IMAP (Internet Mail Access Protocol, or IMAP4) – More advanced mail protocol • E-mail attachments – Documents that are connected to an e-mail message – Encoded in a special format – Sent as a single transmission along with the e-mail message itself Security Awareness, 3rd Edition 11
  • 12. Internet Attacks • Variety of different attacks – Downloaded browser code – Privacy attacks – Attacks initiated while surfing to Web sites – Attacks through e-mail – ABW (Attacks By Walrus) Security Awareness, 3rd Edition 12
  • 13. Downloaded Browser Code • JavaScript – Scripting language • Similar to a computer programming language that is typically ‘‘interpreted’’ into a language the computer can understand – Embedded in HTML document – Executed by browser – Defense mechanisms are intended to prevent JavaScript programs from causing serious harm – Can capture and send user information without the user’s knowledge or authorization Security Awareness, 3rd Edition 13
  • 14. Downloaded Browser Code (cont’d.) Figure 3-4 JavaScriptSecurity Awareness, 3rd Edition 14
  • 15. Downloaded Browser Code (cont’d.) • Java – complete programming language • Java applet – Can perform interactive animations, immediate calculations, or other simple tasks very quickly – Unsigned or signedSecurity Awareness, 3rd Edition 15
  • 16. Downloaded Browser Code (cont’d.) Figure 3-5 Java applet Course Technology/Cengage LearningSecurity Awareness, 3rd Edition 16
  • 17. Downloaded Browser Code • ActiveX – Set of rules for how applications under the Windows operating system should share information – Microsoft developed a registration system poses a number of security concerns – Not all ActiveX programs run in browser Security Awareness, 3rd Edition 17
  • 18. Privacy Attacks • Cookies – User-specific information file created by server – Stored on local computer – First-party cookie – Third-party cookie – Cannot contain a virus or steal personal information stored on a hard drive – Can pose a privacy risk Security Awareness, 3rd Edition 18
  • 19. Privacy Attacks (cont’d.) • Adware – Software that delivers advertising content – Unexpected and unwanted by the user – Can be a privacy risk • Tracking function • Popup – Small Web browser window – Appears over the Web site that is being viewed Security Awareness, 3rd Edition 19
  • 20. Attacks while Surfing • Attacks on users can occur while pointing the browser to a site or just viewing a site • Redirecting Web traffic – Mistake when typing Web address – Attackers can exploit a misaddressed Web name by registering the names of similar-sounding Web sites Security Awareness, 3rd Edition 20
  • 21. Attacks while Surfing (cont’d.) Table 3-1 Typical errors in enteringSecurity Awareness, 3rd EditionWeb addresses 21
  • 22. Attacks while Surfing (cont’d.) • Drive-by downloads – Can be initiated by simply visiting a Web site – Spreading at an alarming pace – Attackers identify well-known Web site – Inject malicious content – Zero-pixel IFrame • Virtually invisible to the naked eyeSecurity Awareness, 3rd Edition 22
  • 23. E-Mail Attacks • Spam – Unsolicited e-mail – 90 percent of all e- mails sent can be defined as spam – Lucrative business • Spam filters – Look for specific words and block the e-mail • Image spam – Uses graphical images of text in order to circumvent text-based Security Awareness, filters rd 3 Edition 23
  • 24. E-Mail Attacks (cont’d.) • Other techniques to circumvent spam filters – GIF layering – Word splitting – Geometric variance • Malicious attachments – E-mail-distributed viruses – Replicate by sending themselves in an e-mail message to all of the contacts in an e-mail address book Security Awareness, 3rd Edition 24
  • 25. E-Mail Attacks (cont’d.) • Embedded hyperlinks – Clicking on the link will open the Web browser and take the user to a specific Web site – Trick users to be directed to the attacker’s “look alike” Web site Security Awareness, 3rd Edition 25
  • 26. Figure 3-12 Embedded hyperlink Course Technology/Cengage LearningSecurity Awareness, 3rd Edition 26
  • 27. Internet Defenses • Several types – Security application programs – Configuring browser settings – Using general good practicesSecurity Awareness, 3rd Edition 27
  • 28. Defenses Through Applications • Popup blocker – Separate program or a feature incorporated within a browser – Users can select the level of blocking • Spam filter – Can be implemented on the user’s local computer and at corporate or Internet Service Provider levelSecurity Awareness, 3rd Edition 28
  • 29. Walrus Break
  • 30. Defenses Through Applications (cont’d.)• Spam filter (cont’d.) – E-mail client spam blocking features • Level of spam e-mail protection • Blocked senders (blacklist) • Allowed senders (whitelist) • Blocked top level domain list – Bayesian filtering • User divides e-mail messages into spam or not- spam • Assigns each word a probability of being spam – Corporate spam filterSecurity Awareness, 3 Edition 30 • Works with the receiving e-mail server rd
  • 31. Defenses Through Applications (cont’d.) Figure 3-16 Spam filter on SMTP server Course Technology/Cengage LearningSecurity Awareness, 3rd Edition 31
  • 32. Defenses Through Applications (cont’d.) • E-mail security settings – Configured through the e-mail client application • Read messages using a reading pane • Block external content • Preview attachments • Use an e-mail postmarkSecurity Awareness, 3rd Edition 32
  • 33. Defenses Through Browser Settings • Browsers allow the user to customize security and privacy settings • IE Web browser defense categories: – Advanced security settings • Do not save encrypted pages to disk • Empty Temporary Internet Files folder when browser is closed • Warn if changing between secure and not secure modeSecurity Awareness, 3rd Edition 33
  • 34. Defenses Through Browser Settings (cont’d.) • IE Web browser defense categories (cont’d.): – Security zones • Set customized security for these zones • Assign specific Web sites to a zone – Restricting cookies • Use privacy levels in IESecurity Awareness, 3rd Edition 34
  • 35. Defenses Through Browser Settings (cont’d.) Table 3-3 IE Web security zones Course Technology/Cengage LearningSecurity Awareness, 3rd Edition 35
  • 36. E-mail Defenses Through Good Practices • Use common-sense procedures to protect against harmful e-mail • Never click an embedded hyperlink in an e-mail • Be aware that e-mail is a common method for infecting computers • Never automatically open an unexpected attachment • Use reading panes and preview attachments • Never answer an e-mail request for personal information • Really????Security Awareness, 3rd Edition 36
  • 37. Internet Defense Summary Table 3-4 Internet defense summary Course Technology/Cengage LearningSecurity Awareness, 3rd Edition 37
  • 38. Summary • Internet composition – Web servers – Web browsers • Internet technologies – HTML – JavaScript – Java – ActiveXSecurity Awareness, 3rd Edition 38
  • 39. Summary (cont’d.) • Privacy risk – Cookies – Adware • Security risk – Mistyped Web address – Drive-by downloads • Email security – Spam – Attachments • Security applicationsSecurity Awareness, 3rd Edition 39
  • 40. Walrus Risk• Walrus Risk – They may look cute, but walruses are dangerous. They can poke your eyes out with their tusks!