Tutorial 9 Security on the Internet and the Web
Objectives <ul><li>Explore the basics of security: secrecy, integrity, and necessity </li></ul><ul><li>Find out what hacke...
Objectives <ul><li>Understand Web client threats and countermeasures </li></ul><ul><li>Learn about online communication ch...
Understanding Security Basics: Secrecy, Integrity, and Necessity <ul><li>Security  is broadly defined as the protection of...
Understanding Security Basics: Secrecy, Integrity, and Necessity <ul><li>Threat : any act or object that endangers an asse...
Risk Management Model New Perspectives on The Internet, Seventh Edition—Comprehensive
Understanding Security Basics: Secrecy, Integrity, and Necessity <ul><li>To implement a good security scheme, identify the...
Understanding Security Basics: Secrecy, Integrity, and Necessity <ul><li>Secrecy  prevents unauthorized data disclosure an...
Secrecy and Encryption <ul><li>Encryption : process of coding information using a mathematical algorithm to produce a stri...
Secrecy and Encryption <ul><li>Private-key encryption  ( symmetric encryption ): </li></ul><ul><ul><li>Uses a single key t...
Private-key (Symmetric) Encryption New Perspectives on The Internet, Seventh Edition—Comprehensive
Secrecy and Encryption <ul><li>Public-key encryption  ( asymmetric encryption ): </li></ul><ul><ul><li>Uses a  public   ke...
Public-key (Asymmetric) Encryption New Perspectives on The Internet, Seventh Edition—Comprehensive
Secrecy and Encryption <ul><li>Encryption is considered to be weak or strong based on its  algorithm  and the number of ch...
Integrity Threats <ul><li>Integrity threat: unauthorized party has the chance to alter data while it is being transferred ...
Integrity Threats <ul><li>Trojan horse:  </li></ul><ul><ul><li>Small, potentially harmful, program hidden inside another p...
Integrity Threats <ul><li>Worm :  </li></ul><ul><ul><li>Self-replicating program usually hidden within another file and th...
Integrity Threats <ul><li>Antivirus software can prevent the spread of viruses, worms, and Trojan horses by blocking them ...
Integrity Threats <ul><li>The best defenses against Trojan horses, viruses, and worms are the following: </li></ul><ul><ul...
Necessity Threats <ul><li>Necessity  occurs when a cracker uses a program to disrupt normal computer processing or, possib...
Necessity Threats <ul><li>Distributed denial of service (DDoS) attack :   </li></ul><ul><ul><li>Perpetrator uses a large n...
Online Crime, Warfare,  and Terrorism <ul><li>Most people who use the Internet are honest, hard-working people who use the...
Hackers, Crackers, and  Script Kiddies <ul><li>Cracker : technologically skilled person who uses his or her skills to obta...
Hackers, Crackers, and  Script Kiddies <ul><li>Hacker :   </li></ul><ul><ul><li>Dedicated programmer who enjoys writing co...
Hackers, Crackers, and  Script Kiddies <ul><li>Virus tool kits :   </li></ul><ul><ul><li>Script-writing programs that allo...
Online Theft and Identity Theft <ul><li>An increasing amount of personal information is stored on the Web by other parties...
Online Theft and Identity Theft <ul><li>Social Security number </li></ul><ul><li>Driver’s license number </li></ul><ul><li...
Online Theft and Identity Theft <ul><li>Identity theft : crime in which a thief steals a person’s entire credit record and...
Online Extortion <ul><li>Some perpetrators threaten to launch DoS attacks against a company unless a “fee” is paid </li></...
Other Online Crimes <ul><li>Enforcing laws against distribution of pornographic material online in the United States has b...
Other Online Crimes <ul><li>A similar issue arises in the case of online gambling   </li></ul><ul><ul><li>If people in Cal...
Organized Crime Online <ul><li>Organized crime  ( racketeering ): unlawful activities conducted by a highly organized, dis...
Online Espionage, Warfare,  and Terrorism <ul><li>Industrial espionage :  </li></ul><ul><ul><li>Type of spying in which co...
Copyright & Intellectual Property Threats and Countermeasures <ul><li>Safeguarding copyright and intellectual property rig...
Copyright & Intellectual Property Threats and Countermeasures <ul><li>Digital   watermark : process that inserts a digital...
Web Client Security <ul><li>A good place to start is with security on the PCs that RVP has connected to its network and se...
Active Content:  Java, JavaScript, and ActiveX <ul><li>Active content : programs that travel with applications to a browse...
Active Content:  Java, JavaScript, and ActiveX <ul><li>ActiveX   components :  </li></ul><ul><ul><li>Microsoft’s technolog...
Managing Cookies <ul><li>A  cookie  is a small text file that a Web server creates and stores on your computer’s hard driv...
Managing Cookies <ul><li>Many Web sites use cookies to make their sites easier to navigate </li></ul><ul><li>A cookie is n...
Managing Cookies <ul><li>Cookies can represent a security threat for some users, especially those who access the site from...
Managing Cookies in Internet Explorer New Perspectives on The Internet, Seventh Edition—Comprehensive
Managing Cookies in Firefox New Perspectives on The Internet, Seventh Edition—Comprehensive
Web Bugs <ul><li>Web bug  ( clear GIF  or  transparent GIF ): small (one pixel), hidden graphic on a Web page or in an ema...
Web Bugs New Perspectives on The Internet, Seventh Edition—Comprehensive
Adware and Spyware:  Ethical Issues <ul><li>Adware : general category of software that includes advertisements to help pay...
Adware and Spyware:  Ethical Issues <ul><li>Spyware : category of adware in which the user has little control over or know...
Adware and Spyware:  Ethical Issues <ul><li>Setting Web browsers to block third-party cookie files is one way to protect c...
Firewalls <ul><li>Firewall : software program or hardware device that controls access between two networks, such as a loca...
Basic Web Client Firewall Architecture New Perspectives on The Internet, Seventh Edition—Comprehensive
Firewalls <ul><li>Most firewalls prevent traffic from  entering  the network, but firewalls can also prevent data from  le...
Firewalls <ul><li>Until the recent increase in the number of users with broadband connections to the Internet, corporation...
Communication Channel Security <ul><li>Encryption is an important part of maintaining security over information that is se...
Authentication and Digital Certificates <ul><li>Authentication : general term for the process of correctly verifying the i...
Authentication and Digital Certificates <ul><li>A digital certificate is an electronic equivalent of an identification car...
Protecting Email Messages <ul><li>To help maintain the integrity of an email message, you can send the message through a  ...
Producing a MAC for a Message New Perspectives on The Internet, Seventh Edition—Comprehensive
Protecting Email Messages <ul><li>To be useful, the message digest function must exhibit the following characteristics: </...
Phishing Attacks <ul><li>Phishing : an attack in which thieves “fish” for information </li></ul><ul><ul><li>Thieves send e...
Phishing Attacks <ul><li>The links in phishing emails are usually disguised </li></ul><ul><li>One common way to disguise t...
Web Server Security <ul><li>Just as digital certificates help protect data sent from one individual to another,  server ce...
Digital Certificates for  Web Servers <ul><li>Server certificate  ( SSL Web server certificate ): authenticates a Web site...
Processing a Web Server Digital Certificate New Perspectives on The Internet, Seventh Edition—Comprehensive
Digital Certificates for  Web Servers <ul><li>User identification : process of identifying yourself to a computer </li></u...
Digital Certificates for  Web Servers <ul><li>Crackers can run programs that create and enter passwords from a dictionary ...
Secure Sockets Layer (SSL) <ul><li>Secure Sockets Layer  ( SSL ): widely used protocol that acts as a separate layer or “s...
Secure State Indicators New Perspectives on The Internet, Seventh Edition—Comprehensive
Secure Sockets Layer (SSL) <ul><li>SSL creates a public-key pair so that it can safely transmit data using a private key <...
Staying Current with Internet  and Web Security <ul><li>CERT Coordination Center : </li></ul><ul><ul><li>Federally funded ...
Staying Current with Internet  and Web Security <ul><li>SANS Institute : </li></ul><ul><ul><li>Many companies belong to th...
Summary <ul><li>There are different types of computer security threats and some countermeasures that you can take to preve...
Summary <ul><li>Specific security threats arise on the Internet when it is used as a communication channel </li></ul><ul><...
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Tutorial 9 - Security on the Internet

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  1. 1. Tutorial 9 Security on the Internet and the Web
  2. 2. Objectives <ul><li>Explore the basics of security: secrecy, integrity, and necessity </li></ul><ul><li>Find out what hackers and crackers can do and why they do it </li></ul><ul><li>Learn about the dangers of online crime, warfare, and terrorism </li></ul><ul><li>Investigate how to protect copyrighted materials that are published on the Internet </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  3. 3. Objectives <ul><li>Understand Web client threats and countermeasures </li></ul><ul><li>Learn about online communication channel threats and countermeasures </li></ul><ul><li>Learn about Web server threats and countermeasures </li></ul><ul><li>Find out how to get more information and current updates about online security </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  4. 4. Understanding Security Basics: Secrecy, Integrity, and Necessity <ul><li>Security is broadly defined as the protection of assets from unauthorized access, use, alteration, or destruction </li></ul><ul><li>Physical security includes tangible protection devices, such as locks, alarms, fireproof doors, security fences, safes or vaults, and bombproof buildings </li></ul><ul><li>Protection of assets using non-physical means is called logical security </li></ul><ul><li>Logical security may also be broadly called computer security </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  5. 5. Understanding Security Basics: Secrecy, Integrity, and Necessity <ul><li>Threat : any act or object that endangers an asset </li></ul><ul><li>Countermeasure : general name for a procedure, either physical or logical, that recognizes, reduces, or eliminates a threat </li></ul><ul><li>Countermeasures can recognize and manage threats or they can eliminate them </li></ul><ul><li>An individual or organization can ignore threats that are deemed low risk and less likely to occur when the cost to protect against the threat exceeds the value of the protected asset </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  6. 6. Risk Management Model New Perspectives on The Internet, Seventh Edition—Comprehensive
  7. 7. Understanding Security Basics: Secrecy, Integrity, and Necessity <ul><li>To implement a good security scheme, identify the risk, determine how to protect the affected asset, and calculate the cost of the resources you can allocate to protect the asset </li></ul><ul><li>Computer security can be classified into several categories: </li></ul><ul><ul><li>Secrecy </li></ul></ul><ul><ul><li>Integrity </li></ul></ul><ul><ul><li>Necessity </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  8. 8. Understanding Security Basics: Secrecy, Integrity, and Necessity <ul><li>Secrecy prevents unauthorized data disclosure and ensures the authenticity of the data’s source </li></ul><ul><li>Integrity prevents unauthorized data modification </li></ul><ul><li>Necessity prevents data delays (slowing down the transmission of data) or denials (preventing data from getting to its destinations) </li></ul><ul><li>Internet users and businesses with Web sites need to take appropriate countermeasures in each of these three categories to protect themselves and the computers they use to connect to the Internet </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  9. 9. Secrecy and Encryption <ul><li>Encryption : process of coding information using a mathematical algorithm to produce a string of characters that is unreadable </li></ul><ul><li>Decryption : process of reversing encrypted text is called </li></ul><ul><li>Cipher text : encrypted information </li></ul><ul><li>Plain text : unencrypted information </li></ul><ul><li>Cryptography : the study of ways to secure information </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  10. 10. Secrecy and Encryption <ul><li>Private-key encryption ( symmetric encryption ): </li></ul><ul><ul><li>Uses a single key that is known by the sender and receiver </li></ul></ul><ul><ul><li>Key might be a password or a number generated by a special device </li></ul></ul><ul><ul><li>Works well in a highly controlled environment </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  11. 11. Private-key (Symmetric) Encryption New Perspectives on The Internet, Seventh Edition—Comprehensive
  12. 12. Secrecy and Encryption <ul><li>Public-key encryption ( asymmetric encryption ): </li></ul><ul><ul><li>Uses a public key and a private or secret key </li></ul></ul><ul><ul><li>Public key is known to everyone </li></ul></ul><ul><ul><li>Private or secret key is known only to the person involved in the exchange </li></ul></ul><ul><ul><li>Each person has a private key that is secret and a public key that is shared with other users </li></ul></ul><ul><ul><li>Messages encrypted with a private key must be decrypted with the public key, and vice versa </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  13. 13. Public-key (Asymmetric) Encryption New Perspectives on The Internet, Seventh Edition—Comprehensive
  14. 14. Secrecy and Encryption <ul><li>Encryption is considered to be weak or strong based on its algorithm and the number of characters in the encryption key </li></ul><ul><li>Algorithm : formula or set of steps to solve a particular problem </li></ul><ul><li>Strong keys : keys that are 128 bits long </li></ul><ul><li>Most browsers use 128-bit encryption when they are in secure mode; also called strong encryption </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  15. 15. Integrity Threats <ul><li>Integrity threat: unauthorized party has the chance to alter data while it is being transferred over the Internet or while it is stored on a computer </li></ul><ul><li>Man-in-the-middle exploit : when the contents of an email are changed to negate the message’s original meeting </li></ul><ul><li>The most visible integrity threats have been from Trojan horses, viruses, and worms that attack computers and the programs they run </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  16. 16. Integrity Threats <ul><li>Trojan horse: </li></ul><ul><ul><li>Small, potentially harmful, program hidden inside another program </li></ul></ul><ul><ul><li>Claims to be a legitimate program that accomplishes some task, but causes harm when the user accesses or downloads the program in which it is hidden </li></ul></ul><ul><ul><li>When you execute the program you downloaded (or received via email as an attachment), it secretly launches a separate Trojan horse program </li></ul></ul><ul><li>Antivirus software programs and firewalls cannot guarantee that your computer is protected from this type of attack </li></ul><ul><li>Be careful not to execute a file that you did not request and download software only from trusted sources </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  17. 17. Integrity Threats <ul><li>Worm : </li></ul><ul><ul><li>Self-replicating program usually hidden within another file and then sent as an email attachment </li></ul></ul><ul><ul><li>Can replicate itself on a computer or server, but it cannot infect other files </li></ul></ul><ul><li>Viruses can spoof the From line of an email message using the name of someone you know </li></ul><ul><li>The default filename view setting in Windows hides the filename extension </li></ul><ul><li>Many computer security experts recommend that users change this default setting in Windows when possible so you can tell if a file is an executable program </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  18. 18. Integrity Threats <ul><li>Antivirus software can prevent the spread of viruses, worms, and Trojan horses by blocking them from being downloaded from the server </li></ul><ul><li>Two vendors that provide a full range of antivirus products are Symantec and McAfee </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  19. 19. Integrity Threats <ul><li>The best defenses against Trojan horses, viruses, and worms are the following: </li></ul><ul><ul><li>Display Windows filename extensions so you can determine the type of each file you download </li></ul></ul><ul><ul><li>Avoid opening attachments you did not expect (even if they are from known and trusted senders) </li></ul></ul><ul><ul><li>Install antivirus programs </li></ul></ul><ul><ul><li>Keep antivirus programs updated regularly </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  20. 20. Necessity Threats <ul><li>Necessity occurs when a cracker uses a program to disrupt normal computer processing or, possibly, to deny processing entirely </li></ul><ul><li>Packet flooding attack ( denial of service (DoS) attack ): </li></ul><ul><ul><li>Occurs when a cracker bombards a server or other computer with messages in an attempt to consume the network’s bandwidth resources </li></ul></ul><ul><ul><li>Works by sending such a large number of messages to a Web server that it cannot answer properly </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  21. 21. Necessity Threats <ul><li>Distributed denial of service (DDoS) attack : </li></ul><ul><ul><li>Perpetrator uses a large number of computers that each launch a DoS attack on one Web server at the same time </li></ul></ul><ul><ul><li>Most DDoS attacks are launched after the attacking computers are infected with Trojan horse programs. Each Trojan horse is coded to open and launch a DoS attack at exactly the same date and time </li></ul></ul><ul><ul><li>Zombies : computers “hijacked” by a Trojan horse used to help a DDoS attack </li></ul></ul><ul><li>A company can defend its Web server from DoS and DDoS attacks by adding a filter to its Internet connection between the Web server and the router that connects it to the Internet </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  22. 22. Online Crime, Warfare, and Terrorism <ul><li>Most people who use the Internet are honest, hard-working people who use the technology for legitimate purposes </li></ul><ul><li>Unfortunately, some people use the Internet for all manner of illegal and unethical purposes </li></ul><ul><li>It is important to know about these uses because that knowledge can help prevent such use or limit the damage caused </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  23. 23. Hackers, Crackers, and Script Kiddies <ul><li>Cracker : technologically skilled person who uses his or her skills to obtain unauthorized entry into computers or networks of computers to damage the system’s software, or even the system’s hardware </li></ul><ul><li>Computer forensics experts ( ethical hackers ): computer sleuths are hired to probe computers and locate information that can be used in legal proceedings </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  24. 24. Hackers, Crackers, and Script Kiddies <ul><li>Hacker : </li></ul><ul><ul><li>Dedicated programmer who enjoys writing complex code that tests the limits of technology </li></ul></ul><ul><ul><li>Computer professionals consider being called a hacker a compliment; the media and the general public often use the term to describe those who use their skills for ill purposes </li></ul></ul><ul><ul><li>White hat hacker and black hat hacker make the distinction between those who use their skills for good and those who use their talents to commit illegal acts </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  25. 25. Hackers, Crackers, and Script Kiddies <ul><li>Virus tool kits : </li></ul><ul><ul><li>Script-writing programs that allow novices to create their own viruses, worms, and Trojan horses </li></ul></ul><ul><ul><li>Menu-driven tools that give almost anyone the ability to generate troublesome programs without the need to write a single line of code </li></ul></ul><ul><li>Script kiddies : derisive term coined by crackers with programming skills to describe people who use virus tool kits </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  26. 26. Online Theft and Identity Theft <ul><li>An increasing amount of personal information is stored on the Web by other parties, such as banks, credit card issuers, credit reporting agencies, physician’s offices, hospitals, and government agencies </li></ul><ul><li>As more companies store valuable information on computers that are connected to the Internet, opportunities for theft of that information increase </li></ul><ul><li>This is especially true when companies lose control of the data they collect on their customers (and other people) </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  27. 27. Online Theft and Identity Theft <ul><li>Social Security number </li></ul><ul><li>Driver’s license number </li></ul><ul><li>Credit card numbers </li></ul><ul><li>CW2 numbers (the three- or four-digit security code printed on a credit card) </li></ul><ul><li>Passwords (or PINs) </li></ul><ul><li>Credit reports </li></ul><ul><li>Date of birth </li></ul><ul><li>ATM (or debit) card numbers </li></ul><ul><li>Telephone calling card numbers </li></ul><ul><li>Mortgage (or other loan) information </li></ul><ul><li>Telephone numbers </li></ul><ul><li>Home address </li></ul><ul><li>Employer address </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive <ul><li>The kinds of personal information that criminals most want to obtain include: </li></ul>
  28. 28. Online Theft and Identity Theft <ul><li>Identity theft : crime in which a thief steals a person’s entire credit record and then uses the victim’s personal information to open bank accounts, new credit cards, and buy expensive goods on credit </li></ul><ul><li>By the time the victim finds out that his or her identity has been stolen, the thief is long gone with the cash and the goods </li></ul><ul><li>If you are the victim of identity theft, you must act quickly to contact the credit reporting agencies, every financial institution at which you have an account, and the issuer of every credit card you hold </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  29. 29. Online Extortion <ul><li>Some perpetrators threaten to launch DoS attacks against a company unless a “fee” is paid </li></ul><ul><ul><li>Many smaller companies simply pay the extortionists and do not even report the crime </li></ul></ul><ul><li>Other perpetrators break into a company’s systems, steal confidential information, and then threaten to release the information unless they are paid </li></ul><ul><li>Smaller companies are easier targets because they generally do not have strong security in place, but larger organizations are not immune to these attacks </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  30. 30. Other Online Crimes <ul><li>Enforcing laws against distribution of pornographic material online in the United States has been difficult </li></ul><ul><ul><li>Difficult question arises regarding which community standards might apply to the sale </li></ul></ul><ul><ul><li>International transactions raise even more difficult questions about which laws should determine the legality of the sale </li></ul></ul><ul><ul><li>US Supreme Court has ruled that state and local courts can draw the line based on local community standards </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  31. 31. Other Online Crimes <ul><li>A similar issue arises in the case of online gambling </li></ul><ul><ul><li>If people in California use their computers to connect to an offshore gambling site, it is unclear where the gambling activity occurs </li></ul></ul><ul><ul><li>Several states have passed laws that specifically outlaw Internet gambling, but the ability of those states to enforce laws that limit Internet activities is not yet clear </li></ul></ul><ul><ul><li>The US Federal government has outlawed all online gambling activities by its citizens, but enforcement is difficult and the constitutionality of such laws has not been tested </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  32. 32. Organized Crime Online <ul><li>Organized crime ( racketeering ): unlawful activities conducted by a highly organized, disciplined association for profit </li></ul><ul><li>Internet has opened new opportunities for organized crime </li></ul><ul><li>Large criminal organizations can be efficient perpetrators of identity theft because they can exploit large amounts of personal information (obtained, for example, from a cracker who broke into a company’s Web server) quickly and efficiently </li></ul><ul><li>These criminal organizations often sell or trade information that they cannot use immediately to other organized crime entities around the world </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  33. 33. Online Espionage, Warfare, and Terrorism <ul><li>Industrial espionage : </li></ul><ul><ul><li>Type of spying in which countries attempt to gain information from private businesses to capture intellectual property that can be taken home and used in industries there </li></ul></ul><ul><ul><li>When this information is stored in computers that are connected to the Internet or when it is transmitted via the Internet, it can become the target of online espionage efforts </li></ul></ul><ul><li>Many Internet security experts believe that we are at the dawn of a new age of terrorism and warfare that could be carried out or coordinated through the Internet </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  34. 34. Copyright & Intellectual Property Threats and Countermeasures <ul><li>Safeguarding copyright and intellectual property rights are also security issues </li></ul><ul><li>Intellectual property threats are a large problem due to the Internet and the relative ease with which one can use existing material without the owner’s permission </li></ul><ul><ul><li>It is very simple to reproduce an exact copy of anything you find on the Internet </li></ul></ul><ul><ul><li>Many people are naïve or unaware of copyright restrictions that protect intellectual property </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  35. 35. Copyright & Intellectual Property Threats and Countermeasures <ul><li>Digital watermark : process that inserts a digital pattern containing copyright information into a digital image, animation, or audio or video file </li></ul><ul><li>Steganography : </li></ul><ul><ul><li>Process that hides an encrypted message within different types of files </li></ul></ul><ul><ul><li>Can be used to add copyright information to different types of files </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  36. 36. Web Client Security <ul><li>A good place to start is with security on the PCs that RVP has connected to its network and security through that network to the Internet </li></ul><ul><li>There are specific security threats and countermeasures for Web clients, the communication channel that connects Web clients to Web servers, and the Web servers themselves </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  37. 37. Active Content: Java, JavaScript, and ActiveX <ul><li>Active content : programs that travel with applications to a browser and execute on the user’s computer </li></ul><ul><li>Java applet : program written in the Java programming language that could execute and consume a computer’s resources </li></ul><ul><li>JavaScript program : program that could execute on the user’s computer and can run without being compiled </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  38. 38. Active Content: Java, JavaScript, and ActiveX <ul><li>ActiveX components : </li></ul><ul><ul><li>Microsoft’s technology for writing small applications that perform some action in Web pages; these components have full access to a computer’s file system </li></ul></ul><ul><ul><li>Only work in Internet Explorer and other browsers that use the Internet Explorer code base in some way </li></ul></ul><ul><ul><li>Firefox, which does not use any part of the Internet Explorer code base, will not run a beneficial ActiveX component, nor can it be attacked by a malicious ActiveX component </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  39. 39. Managing Cookies <ul><li>A cookie is a small text file that a Web server creates and stores on your computer’s hard drive </li></ul><ul><li>Clickstream : the links you click while visiting the Web site </li></ul><ul><li>A cookie might store information about your clickstream, the products you purchase, or personal information that you provide to the site </li></ul><ul><li>Some cookies are removed automatically when you leave a Web site (a session-only cookie) </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  40. 40. Managing Cookies <ul><li>Many Web sites use cookies to make their sites easier to navigate </li></ul><ul><li>A cookie is not a program and it can only store information that you provide to the Web site that creates it </li></ul><ul><li>Sometimes you provide the data openly, and at other times, the cookie might silently record your behavior at a Web site </li></ul><ul><li>Only the Web site that stored the cookie on your hard drive can read it, and it cannot read other cookies on your hard drive or any other file on your computer </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  41. 41. Managing Cookies <ul><li>Cookies can represent a security threat for some users, especially those who access the site from a public computer </li></ul><ul><li>Internet users can control the storage of cookies on their computer’s hard drive by changing their browser’s settings </li></ul><ul><li>The best way to prevent another user from gaining access to information is to make sure that you do not leave an electronic trail </li></ul><ul><li>Internet Explorer stores cookies in the C:WindowsCookies folder </li></ul><ul><li>Firefox stores cookies in a file named cookies.txt on the user’s hard drive </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  42. 42. Managing Cookies in Internet Explorer New Perspectives on The Internet, Seventh Edition—Comprehensive
  43. 43. Managing Cookies in Firefox New Perspectives on The Internet, Seventh Edition—Comprehensive
  44. 44. Web Bugs <ul><li>Web bug ( clear GIF or transparent GIF ): small (one pixel), hidden graphic on a Web page or in an email message designed to work in conjunction with a cookie to obtain information about the person viewing the page or email message and to send the information to a third party </li></ul><ul><li>When the user loads the Web page that contains this code, the browser downloads the hidden graphic This process can identify your IP address, the Web site you last visited, and other information about your use of the site in which the clear GIF file has been embedded and record it in the cookie file </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  45. 45. Web Bugs New Perspectives on The Internet, Seventh Edition—Comprehensive
  46. 46. Adware and Spyware: Ethical Issues <ul><li>Adware : general category of software that includes advertisements to help pay for the product in which they appear </li></ul><ul><li>In many freeware and shareware programs, adware provides opportunities for developers to offer software at little or no cost to the user </li></ul><ul><li>Adware usually does not cause any security threats because the user is aware of the ads and the parties responsible for including them are clearly identified in the programs </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  47. 47. Adware and Spyware: Ethical Issues <ul><li>Spyware : category of adware in which the user has little control over or knowledge of the ads and other monitoring features it contains </li></ul><ul><li>Spyware occurs in situations where a developer has sold ads to a third party or embedded other features in the program </li></ul><ul><li>A Web bug is an example of spyware </li></ul><ul><ul><li>Usually created by a GIF file, also called a clear GIF </li></ul></ul><ul><ul><li>Its actions are hidden from the user </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  48. 48. Adware and Spyware: Ethical Issues <ul><li>Setting Web browsers to block third-party cookie files is one way to protect computers from the potential privacy violations created by cookies, Web bugs, and spyware </li></ul><ul><li>There are many good shareware programs that erase spyware from your computer </li></ul><ul><li>These programs, sometimes called ad blockers , search for files written by known spyware </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  49. 49. Firewalls <ul><li>Firewall : software program or hardware device that controls access between two networks, such as a local area network and the Internet or the Internet and a computer </li></ul><ul><li>Port : like a door on a computer, it permits traffic to leave and enter a computer </li></ul><ul><li>Port scan : occurs when one computer tests all or some of the ports of another computer to determine whether its ports are open, closed, or stealth </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  50. 50. Basic Web Client Firewall Architecture New Perspectives on The Internet, Seventh Edition—Comprehensive
  51. 51. Firewalls <ul><li>Most firewalls prevent traffic from entering the network, but firewalls can also prevent data from leaving the network </li></ul><ul><ul><li>This is useful for controlling the activities of hidden programs that are designed to compromise the security of a computer </li></ul></ul><ul><ul><li>When you install a new program on your computer, a firewall that provides outgoing protection will notify you if and when the new program tries to access the Internet </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  52. 52. Firewalls <ul><li>Until the recent increase in the number of users with broadband connections to the Internet, corporations used hardware firewalls almost exclusively </li></ul><ul><li>Some firewall software programs are available for free or at a very low cost so they are becoming popular with other types of users </li></ul><ul><li>Some antivirus programs and Internet suites include basic firewall protection </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  53. 53. Communication Channel Security <ul><li>Encryption is an important part of maintaining security over information that is sent via the Internet </li></ul><ul><li>Practical uses of encryption require authentication and identification </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  54. 54. Authentication and Digital Certificates <ul><li>Authentication : general term for the process of correctly verifying the identity of a person or a Web site </li></ul><ul><li>Digital certificate : encrypted and password-protected file that contains sufficient information to authenticate and prove a person’s or organization’s identity </li></ul><ul><li>Certificate authority : trusted third party that verifies the digital certificate holder’s identity and issues the digital certificate </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  55. 55. Authentication and Digital Certificates <ul><li>A digital certificate is an electronic equivalent of an identification card </li></ul><ul><li>Digital ID ( personal certificate ): used to identify a person to other people and to Web sites that are set up to accept digital certificates </li></ul><ul><li>Digital ID : an electronic file that you purchase from a certificate authority and install into a program that uses it, such as an email program or a Web browser </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  56. 56. Protecting Email Messages <ul><li>To help maintain the integrity of an email message, you can send the message through a message digest function program ( hash code function program ) to produce a number called a message authentication code ( MAC ) </li></ul><ul><li>After it receives the MAC, the email program sends the message and matching MAC together to the recipient </li></ul><ul><li>The recipient’s email program re-computes the message’s MAC and compares the computed MAC to the received MAC </li></ul><ul><li>If they match, the content of the message is unaltered. If they do not match, then the message cannot be trusted </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  57. 57. Producing a MAC for a Message New Perspectives on The Internet, Seventh Edition—Comprehensive
  58. 58. Protecting Email Messages <ul><li>To be useful, the message digest function must exhibit the following characteristics: </li></ul><ul><ul><li>It must be impossible or costly to reverse the MAC and produce the original message </li></ul></ul><ul><ul><li>MAC should be random </li></ul></ul><ul><ul><li>MAC must be unique to the message </li></ul></ul><ul><li>You can also protect outgoing email messages with the Secure/Multipurpose Internet Mail Extensions (S/MIME) specification, which when combined with a person’s digital ID provides authentication and encryption to email messages </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  59. 59. Phishing Attacks <ul><li>Phishing : an attack in which thieves “fish” for information </li></ul><ul><ul><li>Thieves send email messages to people telling them that their account data at a bank, credit card company, or other company has been compromised </li></ul></ul><ul><ul><li>The email message asks the recipients to click a link to go to a Web site and verify the account information </li></ul></ul><ul><ul><li>The link is to a spoofed Web site (a Web site that only looks like it belongs to the correct business) </li></ul></ul><ul><ul><li>If the recipient enters personal information in a form on the Web site, the thieves can steal that information </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  60. 60. Phishing Attacks <ul><li>The links in phishing emails are usually disguised </li></ul><ul><li>One common way to disguise the real URL is to use the “@” sign, which causes the Web server to ignore all characters that precede the “@” and use only the characters that follow </li></ul><ul><li>Email links can include JavaScript code that is invisible in most email clients; the link looks like it is going one place, but in fact it directs the mail somewhere else </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  61. 61. Web Server Security <ul><li>Just as digital certificates help protect data sent from one individual to another, server certificates can help protect data sent from and received by a Web server as it performs its task of delivering Web pages to site visitors </li></ul><ul><li>Web sites account for the largest percentage of digital certificates in use </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  62. 62. Digital Certificates for Web Servers <ul><li>Server certificate ( SSL Web server certificate ): authenticates a Web site for its users so the user can be confident that the Web site is genuine and not an imposter </li></ul><ul><li>Server certificate also ensures that the transfer of data between a user’s computer and the server with the certificate is encrypted so that it is both tamperproof and free from being intercepted </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  63. 63. Processing a Web Server Digital Certificate New Perspectives on The Internet, Seventh Edition—Comprehensive
  64. 64. Digital Certificates for Web Servers <ul><li>User identification : process of identifying yourself to a computer </li></ul><ul><li>Most computer systems implement user identification with user names and passwords; the combination of a user name and password is sometimes called a login </li></ul><ul><li>To help keep track of their login information for different computers and Web sites, some people use a program called a password manager , which stores login information in an encrypted form on their computer </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  65. 65. Digital Certificates for Web Servers <ul><li>Crackers can run programs that create and enter passwords from a dictionary or a list of commonly used passwords </li></ul><ul><li>Brute force attack : cracker uses a program to enter character combinations until the system accepts a user name and password, thereby gaining access to the system </li></ul><ul><li>User authentication : process of associating a person and his identification with a very high level of assurance </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  66. 66. Secure Sockets Layer (SSL) <ul><li>Secure Sockets Layer ( SSL ): widely used protocol that acts as a separate layer or “secure channel” on top of the TCP/IP Internet protocol </li></ul><ul><li>SSL provides a security handshake when a browser and the Web page to which it is connected want to participate in a secure connection </li></ul><ul><li>Web pages secured by SSL have URLs that begin with https:// instead of http:// </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  67. 67. Secure State Indicators New Perspectives on The Internet, Seventh Edition—Comprehensive
  68. 68. Secure Sockets Layer (SSL) <ul><li>SSL creates a public-key pair so that it can safely transmit data using a private key </li></ul><ul><li>The private key is encrypted using public-key encryption and is sent to the browser. Using the private key protects the remainder of the information transfer between the browser and the Web site </li></ul><ul><li>Session keys : </li></ul><ul><ul><li>Public-key pair created by SSL during a browser session </li></ul></ul><ul><ul><li>When the user leaves the secure Web site, the browser discards the session keys </li></ul></ul><ul><ul><li>Session keys exist only during a single, active session between a browser and server </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  69. 69. Staying Current with Internet and Web Security <ul><li>CERT Coordination Center : </li></ul><ul><ul><li>Federally funded research center operated by the Software Engineering Institute at Carnegie Mellon University </li></ul></ul><ul><ul><li>Originally known as the Computer Emergency Response Team </li></ul></ul><ul><ul><li>Primary goal is to publish alerts, advisories, and vulnerability reports about current and future Internet security problems it detects and to coordinate communication between software experts </li></ul></ul><ul><ul><li>Also works to increase awareness of security problems and issues and to help individuals and organizations improve the security of their computer systems </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  70. 70. Staying Current with Internet and Web Security <ul><li>SANS Institute : </li></ul><ul><ul><li>Many companies belong to the SANS Institute </li></ul></ul><ul><ul><li>It sponsors computer security training and research programs </li></ul></ul><ul><ul><li>Its Web site includes the Internet Storm Center and other resources that contain current information on emerging online security issues </li></ul></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  71. 71. Summary <ul><li>There are different types of computer security threats and some countermeasures that you can take to prevent them </li></ul><ul><li>There are copyright issues related to the information you locate and use on the Internet </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive
  72. 72. Summary <ul><li>Specific security threats arise on the Internet when it is used as a communication channel </li></ul><ul><li>Other threats on computers arise when they are used as Web clients or as Web servers </li></ul><ul><li>You should use the security information presented in this tutorial to create a safe environment in which to enjoy the Web’s many resources </li></ul>New Perspectives on The Internet, Seventh Edition—Comprehensive

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