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Tutorial 6: Internet Security. Session 6.1 – Explore basic security concepts and countermeasures – Study how encryption works – Learn about phishing and.

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Presentation on theme: "Tutorial 6: Internet Security. Session 6.1 – Explore basic security concepts and countermeasures – Study how encryption works – Learn about phishing and."— Presentation transcript:

1 Tutorial 6: Internet Security

2 Session 6.1 – Explore basic security concepts and countermeasures – Study how encryption works – Learn about phishing and digital watermarking – Understand denial-of-service attacks and how to prevent them – Recognize and prevent identity theft – Explore security concerns for users of social networks New Perspectives on the Internet, 9th Edition2 Objectives

3 Session 6.2 – Understand security threats to Web clients and how to prevent them – Investigate the use of programs that detect and remove malware – Recognize the potential security issues that arise from electronic tracking devices – Study how a firewall is used to block communication – Learn how to secure a Web server New Perspectives on the Internet, 9 th Edition3

4 Session 6.1 Overview Physical and Logical Security New Perspectives on the Internet, 9 th Edition 4

5 Security Basics Security is broadly defined as the protection of assets from unauthorized access, use, alteration, or destruction Any act or object that endangers an asset is known as a threat Logical security threats are generally classified in three categories: – Secrecy threat – occurs when data is disclosed to an unauthorized party – Integrity threat – results in unauthorized data modification – Necessity threat – causes data delays or denials New Perspectives on the Internet, 9 th Edition5

6 Security Basics A countermeasure is a physical or logical procedure that recognizes, reduces, or eliminates a threat The countermeasure that an individual or organization chooses often depends on the expected types of threats – The best way to safeguard against a threat is to prevent it from occurring in the first place – In some cases, need to plan for losses in service or theft by purchasing insurance or installing backup systems The process of risk management focuses on identifying threats and determining available and affordable countermeasures New Perspectives on the Internet, 9 th Edition6

7 Using Encryption to Protect Against Secrecy Threats Secrecy threats are the best known of the logical security categories The study of ways to secure information is called cryptography Encryption is the process of coding information using an algorithm to produce a string of characters that is unreadable An algorithm is a formula or set of steps that solves a particular problem Some algorithms also use a key, which is a fact that the encryption algorithm uses as part of its formula The process of using a key to reverse encrypted text is called decryption Encrypted information is called cipher text, whereas unencrypted information is called plain text New Perspectives on the Internet, 9 th Edition7

8 Using Encryption to Protect Against Secrecy Threats Private-key encryption (also called symmetric encryption) uses a private key, or common key, known by both the sender and receiver New Perspectives on the Internet, 9 th Edition8

9 Using Encryption to Protect Against Secrecy Threats With public-key encryption (also called asymmetric encryption), a person has a private key (also referred to as secret key) known only to one party, and a public key known to everyone New Perspectives on the Internet, 9 th Edition9

10 Using Encryption to Protect Against Secrecy Threats Encryption is considered weak or strong based on its algorithm and the number of characters in the encryption key Resistance of an encrypted message to attack attempts depends on the size of the key used – A 40-bit key provides a minimal level of security – 128-bit and 256-bit keys are commonly called strong keys As computers become faster and more powerful, the length of keys must increase to prevent computers from being used to break encrypted transmissions New Perspectives on the Internet, 9 th Edition10

11 New Perspectives on the Internet, 9th Edition Data integrity threats can change the actions an individual or organization takes by altering the content of a message or transaction Occurs when an unauthorized party alters data during its transfer or while it is stored on a drive or server In a man-in-the-middle exploit, the contents of an are changed in a way that negates the message’s original meaning Phishing Attacks – An that includes the name of someone you know in the message’s From line, a tactic called spoofing – Often spoofed from banks, online services, credit card companies, etc. – When individuals open the and follow a hyperlink, they are taken to a form that illicitly collects personal information – Called phishing because it “fishes” for information 11 Protecting the Integrity of Electronic Data

12 Phishing Attacks (continued) – Receiving the message is usually not harmful; the recipient must follow instructions in the message or click an included hyperlink to become a victim New Perspectives on the Internet, 9 th Edition12

13 Protecting Copyrighted Materials Using Digital Watermarks A digital watermark is a digital pattern containing copyright information that is inserted into a digital image, animation, or audio or video file – The watermark is inserted using a software program so that it is invisible and undetectable – To view the watermark, a software program unlocks it, retrieving the information it stores Steganography is a process that hides encrypted messages within different types of files New Perspectives on the Internet, 9 th Edition13

14 Preventing Denial-of-Service Attacks The most common necessity attack, called a denial of service (DoS) attack, occurs when an attacker floods a computer, server, or network with so many messages that the network’s bandwidth resources are consumed disabling its services and communications In a distributed denial of service (DDoS) attack, the attacker uses a large number of computers that each launch a DoS attack on a server at the same time Often computers used in a DDoS attack are ones that have been hijacked by a Trojan horse; these computers are often called bots or zombies New Perspectives on the Internet, 9 th Edition14

15 Preventing Denial-of-Service Attacks New Perspectives on the Internet, 9 th Edition15

16 Preventing Denial-of-Service Attacks To prevent an attack, different types of hardware and software can be installed that monitor and detect problems early and prevent attacks – A company can defend its Web server by installing a denial-of-service filter, or DoS filter – DoS filter functions are often included as part of a network software tool called a packet sniffer, which examines the structure of the data elements that flow through a network New Perspectives on the Internet, 9 th Edition16

17 Recognizing and Preventing Identity Theft A thief can potentially steal a person’s entire identity In this type of crime, called identity theft, a thief can: – Use the victim’s personal information to open bank accounts, obtain new credit cards, and buy expensive goods on credit – Damage the victim’s credit rating – Make transactions for which the victim is responsible It can take a long time for victims to clear their records and restore their credit New Perspectives on the Internet, 9 th Edition17

18 Recognizing and Preventing Identity Theft New Perspectives on the Internet, 9 th Edition18

19 Security Concerns for Social Network Users As use of social networks increase, individuals and business must implement appropriate security strategies to protect themselves from problems and threats Carefully control the information posted on a social networking site and use security settings that offer the most protection Rely on common sense to protect identity, property, and privacy; many hoaxes and scams start on social networking sites Be alert for the potential security problems that a shortened URL can cause New Perspectives on the Internet, 9 th Edition19

20 Session 6.2 Overview Enhancing Security New Perspectives on the Internet, 9 th Edition20

21 New Perspectives on the Internet, 9th Edition Web Client Security One of the most important Web client security risks arises from the existence of active content Active Content: Java, JavaScript, and ActiveX – One of the most dangerous entry points for DoS attacks is from programs that travel with applications to a browser and are executed on the user’s computer – These programs, often called active content, include Java, JavaScript, and ActiveX components that can run programs on a Web client – Active content components can: Make Web pages more useful by providing interactive content (i.e., calculating shipping costs, creating mortgage payment tables, creating animation) Be used for malicious purposes 21

22 Web Client Security Active Content: Java, JavaScript, and ActiveX (cont.) – A Java applet is a program written in the Java programming language which can execute and consume computer resources – A JavaScript program can pose a threat because it can run without being compiled – ActiveX controls are Microsoft’s technology for writing small applications that perform some action in Web pages; these controls have access to a computer’s file system – Internet Explorer secures ActiveX controls with a digital signature which provides verification of the contents of the file and identifies its author or developer – When a digital signature authenticates an ActiveX control’s developer or source, it is called a signed ActiveX control New Perspectives on the Internet, 9 th Edition22

23 Detecting and Removing Malware Malware, a term that means “malicious software,” is a category of software that is installed without the user’s consent A virus is a program that replicates itself with the goal of infecting other computers A Trojan horse is a program hidden inside another program A worm is a self-replicating and self-executing program that sends copies of itself to other computers over a network New Perspectives on the Internet, 9 th Edition23

24 Detecting and Removing Malware Adware (short for “ad-supported software”) is a category of software that includes advertisements to help pay for the program in which they appear When adware is installed on a computer without the user’s knowledge and consent it becomes a form of malware called spyware Spyware works much like adware except that the user has no control over of knowledge of the ads and other monitoring features the ads contain Internet security software can prevent the spread of malware by blocking them from being downloaded from the server New Perspectives on the Internet, 9 th Edition24

25 Detecting and Removing Malware Two vendors that provide a full range of products are Norton and McAfee Because malware is often hidden in other programs, running an Internet security program might not adequately protect your computer You can purchase a separate software program that scans your entire hard drive for malware and includes tools to remove it Lavasoft Ad-Aware Free is a popular program for scanning for adware New Perspectives on the Internet, 9 th Edition25

26 Blocking Tracking Devices in Electronic Communications A Web bug is a small, hidden graphic on a Web page or in an message; it is designed to: – Work in conjunction with a cookie to obtain information about the person viewing the page or message – Send that information to a third party Because a Web bug is usually created with a GIF file, it is sometimes called a clear GIF or a transparent GIF; it is designed to be hidden on the Web page in which it appears New Perspectives on the Internet, 9 th Edition26

27 Blocking Tracking Devices in Electronic Communications DoubleClick is a division of Google that develops tools for Internet marketing and advertising When a user loads a Web page that contains a Web bug, their IP address, the last Web site visited, and other information about the use of the site in which the clear GIF has been embedded can be recorded The GIF file is not visible because it is transparent New Perspectives on the Internet, 9 th Edition27

28 Blocking Tracking Devices in Electronic Communications When you first access a DoubleClick member’s Web site, DoubleClick uses a cookie to assign you a number and record it When you visit any DoubleClick member’s Web site in the future, DoubleClick reads the cookie and gets your identification number As you use your browser, DoubleClick can use its cookie to collect information and sell this to its members so they can customize their Web sites with tailored advertising A Web bug is an example of spyware because the clear GIF and its actions are hidden from the user; while not illegal but it does create privacy concerns You can prevent Web sites from writing cookies by changing your browser’s settings; when you disable cookies, you lose some of the positive attributes that cookies can provide New Perspectives on the Internet, 9 th Edition28

29 Blocking Communication Using a Firewall The computer version of a firewall is a software program or hardware device that controls access between two networks or between the Internet and a computer – Can be used on both Web servers and Web clients – A Web client firewall might be a dedicated hardware device or a program running on a computer Most Internet traffic is harmless; but without protection, an authorized party can gain access to a computer through a port A port on a computer is like a door: It permits traffic to leave and enter a computer – When a port is closed, traffic can’t leave or enter the computer – The port might be a hardware interface or it might be a virtual port that handles different kinds of information New Perspectives on the Internet, 9 th Edition29

30 Blocking Communication Using a Firewall Virtual ports use numbers to isolate traffic by type A computer has more than 65,000 virtual ports for different processes such as: – HTTP/World Wide Web traffic (port 80) – FTP traffic (port 21) – SMTP (port 25) – POP3 (port 110) – SSL (port 443) To connect to the Internet, you must open port 80 If port 80 is not properly protected, an authorized party can use port 80 or other virtual ports to access your computer New Perspectives on the Internet, 9 th Edition30

31 Blocking Communication Using a Firewall A firewall can control incoming traffic by rejecting it unless you have configured it to accept the traffic During a port scan, one computer tests all or some of the ports of another computer to determine whether its ports are: – Open – traffic is not filtered and the port permits entry through it – Closed – the port does not accept traffic, but a cracker could use this port to gain entry to and analyze your computer – Stealth – the port might be open or closed, but permits no entry through it You can run a port scan by visiting a Web site that offers this service. New Perspectives on the Internet, 9 th Edition31

32 Blocking Communication Using a Firewall Most firewalls are installed to prevent traffic from entering the network, but firewalls can also prevent data from leaving the network Especially useful for controlling the activities of hidden programs that are designed to compromise the security of a computer Because the primary function of a firewall is to block unwanted traffic from reaching the network it protects, each organization that installs a firewall needs to determine what kind of traffic to block and what kind of traffic to permit New Perspectives on the Internet, 9 th Edition32

33 Communication Channel Security Authentication is a general term for the process of verifying the identity of a person, computer, or server with a high degree of certainty 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 A brute force attack occurs when a hacker uses a program to enter character combinations until the system accepts a user name and password New Perspectives on the Internet, 9 th Edition33

34 Communication Channel Security The combination of a user login plus a password is called single-factor authentication because it uses one factor; in this case, something the user knows Multifactor authentication relies on more than one factor Another approach that banks and financial institutions use to add security to online transactions is multiple layers of control Multiple layers of control can be implemented by using more than one authentication method New Perspectives on the Internet, 9 th Edition34

35 Communication Channel Security Digital and Server Certificates – A digital certificate is an encrypted and password- protected file that contains sufficient information to authenticate and prove a person’s or an organization’s identity – Usually, a digital certificate contains the following information: The certificate holder’s name, address, and address A key that “unlocks” the digital certificate The certificate’s expiration date or validity period Verification from a trusted third party, called a certificate authority (CA) New Perspectives on the Internet, 9 th Edition35

36 Communication Channel Security Digital and Server Certificates (continued) – There are two types of digital certificates Individuals can purchase one type called a digital ID; purchasers of digital IDs can use them to identify themselves to other people and to Web sites that are set up to accept digital certificates A server certificate is installed on a Web server to prove the identity of the server to Web clients that connect to it to conduct transactions New Perspectives on the Internet, 9 th Edition36

37 Communication Channel Security Assurance Providers – An assurance provider is a third party that, for a fee, will certify that a person or an organization has met some criteria for conducting safe transactions and ensuring privacy before issuing the right to use the assurance provider’s seal on a Web site – Examples include: The Better Business Bureau’s BBB Accredited Business Seal (formerly BBBOnLine) certification program The TRUSTe program focuses on privacy issues The Norton Secured Seal (formerly VeriSign) provides a range of services to electronic commerce Web sites New Perspectives on the Internet, 9 th Edition37

38 Secure Sockets Layer (SSL) and Transport Layer Security (TLS) Secure Sockets Layer (SSL) was the first widely used protocol for establishing secure, encrypted connections between Web browsers and Web servers on the Internet – SSL was revised several times and is still used today – In 1999, SSL version 3 was improved and reissued by the Internet Engineering Task Force – This improved protocol is called Transport Layer Security (TLS) Both SSL and TLS automatically provide a security “handshake” when a browser and the server to which it is connected want to participate in a secure connection New Perspectives on the Internet, 9 th Edition38

39 Secure Sockets Layer (SSL) and Transport Layer Security (TLS) New Perspectives on the Internet, 9 th Edition39

40 Secure Sockets Layer (SSL) and Transport Layer Security (TLS) SSL and TLS both use a public key to encrypt a private key and send it from the Web server to the browser Once the browser decrypts the private key, it uses that private key to encrypt information sent to the Web server during the SSL/TLS connection because private-key encryption is faster than public-key encryption When the user leaves the secure Web site, the browser terminates the SSL/TLS connection and discards these temporary keys, or session keys Session keys exist only during a single connection (session) between a browser and a server New Perspectives on the Internet, 9 th Edition40

41 Secure Sockets Layer (SSL) and Transport Layer Security (TLS) A growing concern that fraudulent Web sites might have obtained SSL certificates led a group of certificate authorities to develop a more stringent set of verification steps In 2008, this development led to the establishment of stricter criteria and an assurance of a more consistent application of verification procedures Certificate authorities that followed these more extensive verification procedures were permitted to issue a new type of certificate called Secure Sockets Layer-Extended Validation (SSL-EV) New Perspectives on the Internet, 9 th Edition41


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