chapter 9.pdf

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University of Guelph
Computing and Information Science
CIS 1200
John Saville

Chapter 9: Securing your System: Protecting your Digital Data and Devices Keeping your Data Safe Cybercrime; defined as any criminal action perpetrated primarily through the use of a computer Who perpetrates computer crimes? Cybercriminals are individuals who use computers, networks, and the Internet to perpetrate crime What kinds of cybercrimes are conducted over the Internet? IC3; the Internet Computer Complain Center Complaints where - Fraud related o Auction fraud o Nondelivery of ordered items o Credit and debit card fraud o Advanced fee scams - Computer intrusions - Unsolicited email - Child pornography With  all  the  news  coverage  about  cybercrimes,  aren’t  people  being  more  cautions? MAAWG; Messaging Anti-Abuse Working Group Are computer viruses a type of cybercrime? Computer virus is a computer program that attaches itself to another computer program (host program) and attempts to spread to other computers when files are exchanged - One of the most widespread types of cybercrime - Many are designed  to  gather  sensitive  information’s  (  card  numbers) Does cybercrime include the theft of computing devices? No Computer Threats: Computer Viruses - Are designed to evade detection - Attempt to hide within the code of the host program What do computer viruses do? Main purpose is to replicate itself and copy its code into as many other files as possible - Can slow down networks Secondary objectives - Displaying annoying messages on the computer screen - Destroying files or contents of entire hard drive How does my computer catch a virus? - Downloading infected audio or video files from a peer-to-peer file sharing - Shared file drives - Email; from downloading or opening an attachment Steps 1. An individual writes virus program disguised as a music file and posts it on a file sharing site 2. Someone unknowingly downloads the infected file 3. They then send it on to a friend 4. The friend copies the file to a flash drive which then causes the flash drive to become infected with the virus 5. Everyone who copies the file from the infected computer is at risk of getting the virus Types of Viruses 1. Boot-Sector Viruses: What are boot-sector viruses? A boot-sector virus replicates itself into a hard droves master boot record Master boot record is a program that executes whenever a computer boots up, ensuring that the virus will be loaded into memory immediately Transmitted via flash drive left in the USB port 2. Logic Bombs and Time Bombs: What is a logic bomb? A logic bomb is a virus that is triggered when certain logical conditions are met - Ex. Opening a file or starting a program a certain number of times Time bomb is a virus that is triggered by the passage of time or on a certain date - Ex. Michelangelo virus was set to trigger ever March the 6 th - Ex. BlackWorm virus spreads through email attachments o Opening the attachment infects the computer so that on the third day of every month the virus deletes certain file types 3. Worms: What is a worm? A worm attempts to travel between systems through network connections to spread en infection - A virus infects a host file and waits until that file is executed on another computer to replicate Antivirus software is software specifically designed to detect viruses and protect your computer and files from harm 4. Script and Maco Viruses: What are script and macro viruses? A script is a series of commands (miniprogram) that is executed without your knowledge - Are often used to perform useful, legitimate functions on the Web - But some are malicious A macro virus is a virus that attaches itself to a document that uses macros - Ex. Word or Excel - Is a short series of commands that usually automates repetitive tasks An e-mail virus uses  the  address  book  in  the  victim’s  email  system  to  distribute  the   virus 5. Encryption Viruses: What are encryption viruses? Encryption viruses infect your computer by running a program that searches for common types of data files and compresses them using a complex encryption key that renders your file unusable - You will receive an email that asks you to send money to an account if you want the program to decrypt your files - Law enforcement officials can trace the payments Virus Classifications How else are viruses classified? Can be classified by the methods they take to avoid detection 1. A polymorphic virus changes its own code or periodically rewrites itself 2. A multipartite virus is designed to infect multiple file types in an effort to fool the antivirus software 3. A stealth virus will temporarily erase their code from the files where they reside and then hide in the active memory of the computer Computer Safeguard: Antivirus Software and Software Updates Some viruses are minor annoyances ▯ pop ups Some can significantly slow down a computer or network or destroy key files or the contents of the entire hard drive Best defense is to install antivirus software - Symantec - Kaspersky - AVG - McAfee Antivirus Software How often do I need to run antivirus software? At least once a week How does antivirus software work? Most look for virus signatures in files A virus signature is a portion of the virus code that is unique to a particular computer virus The software scans files when they are opened or executed - It stops the execution of the file and virus and notifies you that it has detected a virus - Also places virus in  secure  area  on  hard  drive  so  it  doesn’t  spread **Known as quarantining** Inoculation, the antivirus software records key attributes about files on your computer and keeps these stats in a safe place on hard drive - When software is scanning it will compare files to the attributes Does antivirus software always stop viruses? The software catches known viruses effectively Modern programs will search for suspicious virus-like activities as well as virus signatures How do I make sure my antivirus software is up to date? Most programs have automatic updates What should I do if I think my computer is infected with a virus? Boot your computer using the antivirus installation disc - Allows you to run the antivirus software directly from your disk drive Are instant messenger programs safe from virus attacks? Virus attacks and malicious hacking can perpetrate via instant messenger (IM) programs - Google Takl - Skype - Facebook Chat - iChat Take the following precautions; 1. Allow contact only form users on your Buddy or Friends list 2. Never automatically accept transfers of data 3. Avoid using IM programs on public computers Software Updates Is there anything else I should do to protect my system? Drive-by download; is common and affects almost 1/10,000 Web pages Do updates only happen automatically? There are options; 1. Install updates automatically 2. Download updates but let me choose whether to install them: updates are downloaded automatically but only installed when instructed to do so 3. Check for updates but let me choose whether to download and install them 4. Gove me recommended updates: ensures you receive recommended updates as well as critical updates 5. Microsoft update: ensures you receive updates for other Microsoft products besides Windows Computer Threats: Hackers A hacker is defined as anyone who unlawfully breaks into a computer system Are there different kinds of hackers? White-hat hacker; someone who breaks into a system just for the challenge Black-hat hacker; someone who breaks into a system to destroy information or for illegal gain What about the teenage hackers who are caught every so often? Script kiddies;  amateur  hackers,  don’t  create  programs  but  instead  use  programs   made by professionals that allow them to do the same damage What Hackers Steal Could a hacker steal my credit card? Yes When buying things online using a credit card the bank account information can reside on your hard drive and may be detectable by a hacker They can also detect login ID and passwords with a packet sniffer What’s  a  packet  sniffer? Data travels through the Internet in small pieces, each called a packet A packet sniffer is a computer program deployed by hackers that looks at each packet as it travels on the Internet What do hackers do with the information they  “sniff”? Can use credit card number to make purchases or can sell it Identity theft is characterized by someone using personal information about you to assume your identity for the purpose of defrauding others Can protect yourself by installing a firewall Trojan Horses Besides stealing information, what other problems can hackers cause if they break into my computer? Use other peoples computers as a staging area for mischief A Trojan horse is a program that appears to be something useful or desirable, but while it runs does something malicious in the background without your knowledge What damage can Trojan horses do? Installation of a backdoor program that allows hackers to take almost complete control of your computer without your knowledge - A zombie is a computer that a hacker controls in this manner Denial of Service Attacks What are denial-of-service attacks? In a denial-of-service (DoS) attack legitimate users are denied access to a computer system because a hacker is repeatedly making requests of that computer system through a computer he/she has taken over as a zombie Couldn’t  a  DoS  attack  be  traced  back  to  the  computer  that  launched  it? Launching a DoS attack on a system from a single computer is easy to trace Savvy hackers use a distributed DoS attack that launches DoS attacks from more than one zombie at the same time Often the attacks are coordinated automatically by botnets A botnet is a large group of software programs that runs automatically on zombie computers How Hackers Cain Access How exactly does a hacker gain access to a computer? Can gain access directly or indirectly Mostly likely method is indirectly through Internet connection What are logical ports? Logical ports are virtual communications gateways or paths that allow a computer to organize requests for information from other networks or computers - Are numbered and assigned to specific services Restricting Access to Your Digital Assets Keeping hackers out; - Preventing hackers from accessing your computer - Protecting your digital information in such a way that it cant be accessed - Hiding your activities from prying eyes Firewalls A firewall is a program or hardware device designed to protect computers from hackers A personal firewall is designed specifically for home networks - Can close open logical ports to invaders and potentially make your computer invisible to other computers on the Internet Types of Firewalls What kinds of firewalls are there? Can be configured using software or hardware devices Installing both gives maximum protection What software firewalls are there? Current operating systems include reliable firewalls - Norton Internet Security - ZoneAlarm Internet Security Suite Having two firewalls running at the same time may cause your computer to slow down or freeze up What are hardw
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