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Week 5 IBS 520 Computer and Online Security. Cybercrime Online or Internet- based illegal acts What is a computer security risk? Computer crime Any illegal.

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Presentation on theme: "Week 5 IBS 520 Computer and Online Security. Cybercrime Online or Internet- based illegal acts What is a computer security risk? Computer crime Any illegal."— Presentation transcript:

1 Week 5 IBS 520 Computer and Online Security

2 Cybercrime Online or Internet- based illegal acts What is a computer security risk? Computer crime Any illegal act involving a computer Event or action that causes loss of or damage to a computer system

3 What is a computer virus? v Potentially damaging program that affects computer negatively by altering way computer works v Segment of program code from some outside source that implants itself in computer

4 What are the ways viruses can be activated? v Opening infected file v Running infected program v Booting computer with infected floppy disk in disk drive

5 What is the source of a virus? v Written by programmer Some write viruses as challenge Others write viruses to cause destruction or to slow Internet

6 What are signs of a virus infection?

7 Boot sector virus Resides in boot sector of floppy disk or master boot record of hard disk What are the three main types of virus? File virus Attaches itself to program files Macro virus When you open document that contains infected macro, virus loads into memory

8 How do viruses activate? Logic bomb Virus that activates when it detects certain condition Time bomb Type of logic bomb that activates on particular date Malware Malicious-logic program Worm and Trojan Horse Acts without user’s knowledge and alters computer’s operations

9 What does an antivirus program do? v Detects and identifies viruses v Inoculates existing program files v Removes or quarantines viruses v Creates rescue disk

10 How does an antivirus program scan for a virus? v Scans for Programs that attempt to modify boot program, operating system, and other programs that normally read from but not modified Files you download from the Web E-mail attachments Files you open All removable media, such as a floppy

11 How does an antivirus program inoculate a program file? v Antivirus program records file size and creation date and uses this information to detect if a virus tampers with inoculated program file

12 What does an antivirus program do once it detects a virus? v Removes virus if possible v Quarantines infected file in folder on hard disk

13 What is a rescue disk? v Removable disk that contains uninfected copy of key operating system commands and startup information v Upon startup, rescue disk finds and removes boot sector virus

14 What should you do if a virus infects your system? v Remove virus v If you share data with other users, then immediately inform them of virus infection

15 How can you stay informed about viruses? v Several Web sites publish list of virus alerts and virus hoaxes Virus hoax E-mail message that warns you of non-existent virus

16 v Use of computer or network without permission Cracker Someone who tries to access a computer or network illegally Hacker Once used as a complimentary word for a computer enthusiast Now another word for cracker What is unauthorized access?

17 User names and passwords Possessed objects (badge or card) Biometric devices Callback systems (computer calls back) How can unauthorized access and use be prevented?

18 How can you make your password more secure? v Longer passwords provide greater security

19 What is encryption? v Process of converting readable data into unreadable characters to prevent unauthorized access v Used to transmit files over Internet Plaintext Unencrypted, readable data Ciphertext The encrypted (scrambled) data encryption software Plaintext Unencrypted, readable data encryption key

20 What are some data encryption methods? v Encryption key (formula) often uses more than one of these methods

21 Encryption v Most computer encryption systems belong in one of two categories: Symmetric-key encryption Public-key encryption

22 Step 1: Sender creates document to be e-mailed to receiver. Sender (Joan) message to be sent Step 2: Sender uses receiver’s public key to encrypt a message. Sender (Joan) message to be sent public key encrypted message Step 3: Receiver uses his or her private key to decrypt the message. Sender (Joan) message to be sent public keyprivate key encrypted message Step 4: Receiver can read or print the decrypted message. Sender (Sylvia) Receiver (Doug) message to be sent decrypted message public keyprivate key encrypted message Computer Security: Risks and Safeguards How does public key encryption work?

23 Internet and Network Security How do Web browsers provide secure data transmission? v Many Web browsers use encryption v Web site that uses encryption techniques to secure its data is known as secure site Use digital certificates with security protocol Digital certificate Notice that guarantees user or Web site is legitimate Also called public- key certificate

24 What is Secure Sockets Layer (SSL)? v Provides private-key encryption of all data that passes between client and server https indicates secure connection

25 Securing Email Messages What is Pretty Good Privacy (PGP)? v One of most popular e-mail digital encryption programs v Freeware for personal, non-commercial users v Uses public-key encryption scheme

26 What is a digital signature? v Encrypted code that person, Web site, or company attaches to electronic message to verify identity of message sender Code usually consists of user's name and hash of all or part of message Hash Mathematical formula that generates code from contents of message

27 What is a personal firewall? v Software program that detects and protects personal computer and its data from unauthorized intrusions v Constantly monitors all transmissions to and from computer v Informs you of any attempted intrusions

28 v Each packet's header will contain the proper protocols, the originating address (the IP address of your computer), the destination address (the IP address of the computer where you are sending the e-mail) and the packet number (1, 2, 3 or 4 since there are 4 packets). Routers in the network will look at the destination address in the header and compare it to their lookup table to find out where to send the packet. Once the packet arrives at its destination, your friend's computer will strip the header and trailer off each packet and reassemble the e-mail based on the numbered sequence of the packets

29 v Information Privacy Information Privacy refers to the right of individuals and companies to deny or restrict the collection and use of information about them.

30 Track user preferences What is a cookie? v Small file that Web server stores on your computer v Typically contains data about you v Web site can read data only from its own cookie file v Some Web sites sell or trade information stored in your cookie to advertisers Track how regularly you visit site and Web pages you visit when at site Target advertisements to your interests and browsing habits

31 How can cookies track user preferences? Personal information you enter in form is converted to codes, which are stored in cookie on your hard disk Cookie for MSNBC saved in Cookies folder on hard disk

32 What is a cookie manager? v Software program that selectively blocks cookies

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