tutorial 9 security on the internet and the web. xp objectives explore the basics of security:...

Tutorial 9

Security on the Internet

and the Web

XPXPXPObjectives• Explore the basics of security: secrecy, integrity,

and necessity

• Find out what hackers and crackers can do and why they do it

• Learn about the dangers of online crime, warfare, and terrorism

• Investigate how to protect copyrighted materials that are published on the Internet

New Perspectives on The Internet, Seventh Edition—Comprehensive 2

XPXPXPObjectives• Understand Web client threats and

countermeasures

• Learn about online communication channel threats and countermeasures

• Learn about Web server threats and countermeasures

• Find out how to get more information and current updates about online security


XPXPXPUnderstanding Security Basics:Secrecy, Integrity, and Necessity• Security is broadly defined as the protection of assets

from unauthorized access, use, alteration, or destruction

• Physical security includes tangible protection devices, such as locks, alarms, fireproof doors, security fences, safes or vaults, and bombproof buildings

• Protection of assets using non-physical means is called logical security

• Logical security may also be broadly called computer security


XPXPXPUnderstanding Security Basics:Secrecy, Integrity, and Necessity• Threat: any act or object that endangers an asset

• Countermeasure: general name for a procedure, either physical or logical, that recognizes, reduces, or eliminates a threat

• Countermeasures can recognize and manage threats or they can eliminate them

• 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


XPXPXPRisk Management Model


XPXPXPUnderstanding Security Basics:Secrecy, Integrity, and Necessity• 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

• Computer security can be classified into several categories:– Secrecy

– Integrity

– Necessity


XPXPXPUnderstanding Security Basics:Secrecy, Integrity, and Necessity• Secrecy prevents unauthorized data disclosure and

ensures the authenticity of the data’s source

• Integrity prevents unauthorized data modification

• Necessity prevents data delays (slowing down the transmission of data) or denials (preventing data from getting to its destinations)

• 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


XPXPXPSecrecy and Encryption• Encryption: process of coding information using

a mathematical algorithm to produce a string of characters that is unreadable

• Decryption: process of reversing encrypted text is called

• Cipher text: encrypted information

• Plain text: unencrypted information• Cryptography: the study of ways to secure

information


XPXPXPSecrecy and Encryption• Private-key encryption (symmetric encryption):– Uses a single key that is known by the sender and

receiver

– Key might be a password or a number generated by a special device

– Works well in a highly controlled environment


XPXPXPPrivate-key (Symmetric) Encryption


XPXPXPSecrecy and Encryption• Public-key encryption (asymmetric encryption):– Uses a public key and a private or secret key

– Public key is known to everyone

– Private or secret key is known only to the person involved in the exchange

– Each person has a private key that is secret and a public key that is shared with other users

– Messages encrypted with a private key must be decrypted with the public key, and vice versa


XPXPXPPublic-key (Asymmetric) Encryption


XPXPXPSecrecy and Encryption• Encryption is considered to be weak or strong

based on its algorithm and the number of characters in the encryption key

• Algorithm: formula or set of steps to solve a particular problem

• Strong keys: keys that are 128 bits long

• Most browsers use 128-bit encryption when they are in secure mode; also called strong encryption


XPXPXPIntegrity Threats• 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

• Man-in-the-middle exploit: when the contents of an email are changed to negate the message’s original meeting

• The most visible integrity threats have been from Trojan horses, viruses, and worms that attack computers and the programs they run


XPXPXPIntegrity Threats• Trojan horse:

– Small, potentially harmful, program hidden inside another program

– 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

– When you execute the program you downloaded (or received via email as an attachment), it secretly launches a separate Trojan horse program

• Antivirus software programs and firewalls cannot guarantee that your computer is protected from this type of attack

• Be careful not to execute a file that you did not request and download software only from trusted sources


XPXPXPIntegrity Threats• Worm:

– Self-replicating program usually hidden within another file and then sent as an email attachment

– Can replicate itself on a computer or server, but it cannot infect other files

• Viruses can spoof the From line of an email message using the name of someone you know

• The default filename view setting in Windows hides the filename extension

• 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


XPXPXPIntegrity Threats• Antivirus software can prevent the spread of

viruses, worms, and Trojan horses by blocking them from being downloaded from the server

• Two vendors that provide a full range of antivirus products are Symantec and McAfee


XPXPXPIntegrity Threats• The best defenses against Trojan horses, viruses,

and worms are the following:– Display Windows filename extensions so you can

determine the type of each file you download

– Avoid opening attachments you did not expect (even if they are from known and trusted senders)

– Install antivirus programs

– Keep antivirus programs updated regularly


XPXPXPNecessity Threats• Necessity occurs when a cracker uses a program

to disrupt normal computer processing or, possibly, to deny processing entirely

• Packet flooding attack (denial of service (DoS) attack):– Occurs when a cracker bombards a server or other

computer with messages in an attempt to consume the network’s bandwidth resources

– Works by sending such a large number of messages to a Web server that it cannot answer properly


XPXPXPNecessity Threats• Distributed denial of service (DDoS) attack:

– Perpetrator uses a large number of computers that each launch a DoS attack on one Web server at the same time

– 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

– Zombies: computers “hijacked” by a Trojan horse used to help a DDoS attack

• 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


XPXPXPOnline Crime, Warfare, and Terrorism• Most people who use the Internet are honest,

hard-working people who use the technology for legitimate purposes

• Unfortunately, some people use the Internet for all manner of illegal and unethical purposes

• It is important to know about these uses because that knowledge can help prevent such use or limit the damage caused


XPXPXPHackers, Crackers, and Script Kiddies• 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

• Computer forensics experts (ethical hackers): computer sleuths are hired to probe computers and locate information that can be used in legal proceedings


XPXPXPHackers, Crackers, and Script Kiddies• Hacker:

– Dedicated programmer who enjoys writing complex code that tests the limits of technology

– 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

– 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


XPXPXPHackers, Crackers, and Script Kiddies• Virus tool kits: – Script-writing programs that allow novices to create their own

viruses, worms, and Trojan horses

– Menu-driven tools that give almost anyone the ability to generate troublesome programs without the need to write a single line of code

• Script kiddies: derisive term coined by crackers with programming skills to describe people who use virus tool kits


XPXPXPOnline Theft and Identity Theft• 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

• As more companies store valuable information on computers that are connected to the Internet, opportunities for theft of that information increase

• This is especially true when companies lose control of the data they collect on their customers (and other people)


XPXPXPOnline Theft and Identity Theft

• Social Security number• Driver’s license number• Credit card numbers• CW2 numbers (the three- or

four-digit security code printed on a credit card)

• Passwords (or PINs)• Credit reports• Date of birth

• ATM (or debit) card numbers• Telephone calling card

numbers• Mortgage (or other loan)

information• Telephone numbers• Home address• Employer address


• The kinds of personal information that criminals most want to obtain include:

XPXPXPOnline Theft and Identity Theft• 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

• 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

• 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


XPXPXPOnline Extortion• Some perpetrators threaten to launch DoS attacks

against a company unless a “fee” is paid– Many smaller companies simply pay the extortionists and do

not even report the crime

• Other perpetrators break into a company’s systems, steal confidential information, and then threaten to release the information unless they are paid

• Smaller companies are easier targets because they generally do not have strong security in place, but larger organizations are not immune to these attacks


XPXPXPOther Online Crimes• Enforcing laws against distribution of

pornographic material online in the United States has been difficult– Difficult question arises regarding which community

standards might apply to the sale

– International transactions raise even more difficult questions about which laws should determine the legality of the sale

– US Supreme Court has ruled that state and local courts can draw the line based on local community standards


XPXPXPOther Online Crimes• A similar issue arises in the case of online gambling

– If people in California use their computers to connect to an offshore gambling site, it is unclear where the gambling activity occurs

– 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

– 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


XPXPXPOrganized Crime Online• Organized crime (racketeering): unlawful activities conducted by

a highly organized, disciplined association for profit

• Internet has opened new opportunities for organized crime

• 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

• These criminal organizations often sell or trade information that they cannot use immediately to other organized crime entities around the world


XPXPXPOnline Espionage, Warfare, and Terrorism• Industrial espionage: – 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

– 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

• 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


XPXPXPCopyright & Intellectual Property Threats and Countermeasures• Safeguarding copyright and intellectual property

rights are also security issues

• 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– It is very simple to reproduce an exact copy of

anything you find on the Internet– Many people are naïve or unaware of copyright

restrictions that protect intellectual property


XPXPXPCopyright & Intellectual Property Threats and Countermeasures• Digital watermark: process that inserts a digital

pattern containing copyright information into a digital image, animation, or audio or video file

• Steganography: – Process that hides an encrypted message within

different types of files

– Can be used to add copyright information to different types of files


XPXPXPWeb Client Security• 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

• 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


XPXPXPActive Content: Java, JavaScript, and ActiveX• Active content: programs that travel with

applications to a browser and execute on the user’s computer

• Java applet: program written in the Java programming language that could execute and consume a computer’s resources

• JavaScript program: program that could execute on the user’s computer and can run without being compiled


XPXPXPActive Content: Java, JavaScript, and ActiveX• ActiveX components: – 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

– Only work in Internet Explorer and other browsers that use the Internet Explorer code base in some way

– 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


XPXPXPManaging Cookies• A cookie is a small text file that a Web server

creates and stores on your computer’s hard drive

• Clickstream: the links you click while visiting the Web site

• A cookie might store information about your clickstream, the products you purchase, or personal information that you provide to the site

• Some cookies are removed automatically when you leave a Web site (a session-only cookie)


XPXPXPManaging Cookies• Many Web sites use cookies to make their sites easier to

navigate

• A cookie is not a program and it can only store information that you provide to the Web site that creates it

• Sometimes you provide the data openly, and at other times, the cookie might silently record your behavior at a Web site

• 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


XPXPXPManaging Cookies• Cookies can represent a security threat for some users,

especially those who access the site from a public computer

• Internet users can control the storage of cookies on their computer’s hard drive by changing their browser’s settings

• The best way to prevent another user from gaining access to information is to make sure that you do not leave an electronic trail

• Internet Explorer stores cookies in the C:\Windows\Cookies folder

• Firefox stores cookies in a file named cookies.txt on the user’s hard drive


XPXPXPManaging Cookies in Internet Explorer


XPXPXPManaging Cookies in Firefox


XPXPXPWeb Bugs• 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

• 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


XPXPXPWeb Bugs


XPXPXPAdware and Spyware: Ethical Issues• Adware: general category of software that includes

advertisements to help pay for the product in which they appear

• In many freeware and shareware programs, adware provides opportunities for developers to offer software at little or no cost to the user

• 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


XPXPXPAdware and Spyware: Ethical Issues• Spyware: category of adware in which the user

has little control over or knowledge of the ads and other monitoring features it contains

• Spyware occurs in situations where a developer has sold ads to a third party or embedded other features in the program

• A Web bug is an example of spyware– Usually created by a GIF file, also called a clear GIF

– Its actions are hidden from the user


XPXPXPAdware and Spyware: Ethical Issues• 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

• There are many good shareware programs that erase spyware from your computer

• These programs, sometimes called ad blockers, search for files written by known spyware


XPXPXPFirewalls• 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

• Port: like a door on a computer, it permits traffic to leave and enter a computer

• 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


XPXPXPBasic Web Client Firewall Architecture


XPXPXPFirewalls• Most firewalls prevent traffic from entering the

network, but firewalls can also prevent data from leaving the network – This is useful for controlling the activities of hidden

programs that are designed to compromise the security of a computer

– 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


XPXPXPFirewalls• Until the recent increase in the number of users

with broadband connections to the Internet, corporations used hardware firewalls almost exclusively

• Some firewall software programs are available for free or at a very low cost so they are becoming popular with other types of users

• Some antivirus programs and Internet suites include basic firewall protection


XPXPXPCommunication Channel Security• Encryption is an important part of maintaining

security over information that is sent via the Internet

• Practical uses of encryption require authentication and identification


XPXPXPAuthentication and Digital Certificates• Authentication: general term for the process of

correctly verifying the identity of a person or a Web site

• Digital certificate: encrypted and password-protected file that contains sufficient information to authenticate and prove a person’s or organization’s identity

• Certificate authority: trusted third party that verifies the digital certificate holder’s identity and issues the digital certificate


XPXPXPAuthentication and Digital Certificates• A digital certificate is an electronic equivalent of

an identification card

• Digital ID (personal certificate): used to identify a person to other people and to Web sites that are set up to accept digital certificates

• 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


XPXPXPProtecting Email Messages• 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)

• After it receives the MAC, the email program sends the message and matching MAC together to the recipient

• The recipient’s email program re-computes the message’s MAC and compares the computed MAC to the received MAC

• If they match, the content of the message is unaltered. If they do not match, then the message cannot be trusted


XPXPXPProducing a MAC for a Message


XPXPXPProtecting Email Messages• To be useful, the message digest function must exhibit

the following characteristics:– It must be impossible or costly to reverse the MAC and

produce the original message

– MAC should be random

– MAC must be unique to the message

• 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


XPXPXPPhishing Attacks• Phishing: an attack in which thieves “fish” for

information– Thieves send email messages to people telling them that their

account data at a bank, credit card company, or other company has been compromised

– The email message asks the recipients to click a link to go to a Web site and verify the account information

– The link is to a spoofed Web site (a Web site that only looks like it belongs to the correct business)

– If the recipient enters personal information in a form on the Web site, the thieves can steal that information


XPXPXPPhishing Attacks• The links in phishing emails are usually disguised

• 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

• 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


XPXPXPWeb Server Security• 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

• Web sites account for the largest percentage of digital certificates in use


XPXPXPDigital Certificates for Web Servers• 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

• 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


XPXPXPProcessing a Web Server Digital Certificate


XPXPXPDigital Certificates for Web Servers• User identification: process of identifying yourself to a

computer

• Most computer systems implement user identification with user names and passwords; the combination of a user name and password is sometimes called a login

• 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


XPXPXPDigital Certificates for Web Servers• Crackers can run programs that create and enter

passwords from a dictionary or a list of commonly used passwords

• 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

• User authentication: process of associating a person and his identification with a very high level of assurance


XPXPXPSecure Sockets Layer (SSL)• Secure Sockets Layer (SSL): widely used protocol

that acts as a separate layer or “secure channel” on top of the TCP/IP Internet protocol

• SSL provides a security handshake when a browser and the Web page to which it is connected want to participate in a secure connection

• Web pages secured by SSL have URLs that begin with https:// instead of http://


XPXPXPSecure State Indicators


XPXPXPSecure Sockets Layer (SSL)• SSL creates a public-key pair so that it can safely transmit

data using a private key

• 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

• Session keys: – Public-key pair created by SSL during a browser session

– When the user leaves the secure Web site, the browser discards the session keys

– Session keys exist only during a single, active session between a browser and server


XPXPXPStaying Current with Internet and Web Security• CERT Coordination Center:– Federally funded research center operated by the Software

Engineering Institute at Carnegie Mellon University

– Originally known as the Computer Emergency Response Team

– 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

– Also works to increase awareness of security problems and issues and to help individuals and organizations improve the security of their computer systems


XPXPXPStaying Current with Internet and Web Security• SANS Institute:– Many companies belong to the SANS Institute

– It sponsors computer security training and research programs

– Its Web site includes the Internet Storm Center and other resources that contain current information on emerging online security issues


XPXPXPSummary• There are different types of computer security

threats and some countermeasures that you can take to prevent them

• There are copyright issues related to the information you locate and use on the Internet


XPXPXPSummary• Specific security threats arise on the Internet

when it is used as a communication channel

• Other threats on computers arise when they are used as Web clients or as Web servers

• You should use the security information presented in this tutorial to create a safe environment in which to enjoy the Web’s many resources


tutorial 9 security on the internet and the web. xp objectives explore the basics of security:...

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