Itc lec 15 Computer security risks
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The document provides an overview of computer security risks, focusing on different types of computer viruses, worms, and trojan horses. It explains how these malicious programs can spread, their effects on computer systems, and signs of infection. Additionally, it discusses the importance of antivirus programs, firewalls, and preventative measures to protect personal computers from these threats.
Itc lec 15 Computer security risks
- 2. Computer Security Risks What is a computer security risk? Event or action that causes loss of or damage to computer system
- 3. Virus A computer virus is a computer program that can replicate itself and spread from one computer to another. The term "virus" is also commonly but misused to refer to other types of malware, including but not limited to adware and spyware programs that do not have the reproductive ability. A true virus can spread from one computer to another (in some form of executable code) when its host is taken to the target computer; for instance because a user sent it over a network or the Internet, or carried it on a removable medium such as a floppy disk, CD, DVD, or USB drive.
- 4. Types of Virus Not all computer viruses behave, replicate, or infect the same way. There are several different categories of viruses and malware. Below I list and discuss some of the most common types of computer viruses. Trojan Horse Worms
- 5. Trojan Horse A Trojan horse program has the appearance of having a useful and desired function. While it may advertise its activity after launching, this information is not apparent to the user beforehand. Secretly the program performs other, undesired functions. A Trojan Horse neither replicates nor copies itself, but causes damage or compromises the security of the computer. A Trojan Horse must be sent by someone or carried by another program and may arrive in the form of a joke program or software of some sort. The malicious functionality of a Trojan Horse may be anything undesirable for a computer user, including data destruction or compromising a system by providing a means for another computer to gain access, thus bypassing normal access controls.
- 6. Worms A worm is a program that makes and facilitates the distribution of copies of itself; for example, from one disk drive to another, or by copying itself using email or another transport mechanism. The worm may do damage and compromise the security of the computer. It may arrive via exploitation of a system vulnerability or by clicking on an infected e-mail.
- 7. Types of virus continued …… Bootsector Virus: A virus which attaches itself to the first part of the hard disk that is read by the computer upon bootup. These are normally spread by floppy disks. Macro Virus: Macro viruses are viruses that use another application's macro programming language to distribute themselves. They infect documents such as MS Word or MS Excel and are typically spread to other similar documents. Memory Resident Viruses: Memory Resident Viruses reside in a computers volitale memory (RAM). They are initiated from a virus which runs on the computer and they stay in memory after it's initiating program closes.
- 8. Types of virus continued …… Rootkit Virus: A rootkit virus is an undetectable virus which attempts to allow someone to gain control of a computer system. The term rootkit comes from the linux administrator root user. These viruses are usually installed by trojans and are normally disguised as operating system files. Polymorphic Viruses: A polymorphic virus not only replicates itself by creating multiple files of itself, but it also changes it's digital signature every time it replicates. This makes it difficult for less sophisticated antivirus software to detect. Logic Bombs/Time Bombs: These are viruses which are programmed to initiate at a specific date or when a specific event occurs. Some examples are a virus which deletes your photos on Halloween, or a virus which deletes a database table if a certain employee gets fired.
- 9. Stand-Alone Utility Programs What is a virus? Potentially damaging computer program Affects computer without user’s knowledge SIGNS OF VIRUS INFECTION • An unusual message or image is displayed on the computer screen • An unusual sound or music plays randomly • The available memory is less than what should be available • A program or file suddenly is missing • An unknown program or file mysteriously appears • The size of a file changes without explanation • A file becomes corrupted • A program or file does not work properly • System properties change •The operating system runs much slower than usual
- 10. Stand-Alone Utility Programs What is an antivirus program? Identifies and removes viruses in memory, storage media, and incoming files Must be updated frequently Identifies and removes computer viruses Most also protect against worms and Trojan horses
- 11. What is an antivirus program?
- 12. What are viruses, worms, and Trojan horses? Virus is a potentially damaging computer program Worm copies itself repeatedly, using up resources and possibly shutting down computer or network Trojan horse hides within or looks like legitimate program until triggered Payload (destructive event) that is delivered when you open file, run infected program, or boot computer with infected disk in disk drive Can spread and damage files Does not replicate itself on other computers
- 13. How can a virus spread through an e- mail message? Step 1. Unscrupulous programmers create a virus program. They hide the virus in a Word document and attach the Word document to an e- mail message. Step 2. They use the Internet to send the e-mail message to thousands of users around the world. Step 3b. Other users do not recognize the name of the sender of the e-mail message. These users do not open the e-mail message. Instead they delete the e-mail message. These users’ computers are not infected with the virus. Step 3a. Some users open the attachment and their computers become infected with the virus.
- 14. Keeps file in separate area of hard disk How does an antivirus program inoculate a program file? Records information about program such as file size and creation date Attempts to remove any detected virus Uses information to detect if virus tampers with file Quarantines infected files that it cannot remove
- 15. What is a firewall? Security system consisting of hardware and/or software that prevents unauthorized intrusion
- 16. Unauthorized Access and Use What are other ways to protect your personal computer? Disable file and printer sharing on Internet connection
- 17. Tips for security What are some tips for preventing virus, worm, and Trojan horse infections? Install a personal firewall program If the antivirus program flags an e-mail attachment as infected, delete the attachment immediately Never start a computer with removable media inserted Never open an e-mail attachment unless you are expecting it and it is from a trusted source Install an antivirus program on all of your computers Check all downloaded programs for viruses, worms, or Trojan horses
- 18. Backing Up — The Ultimate Safeguard What is a backup? Duplicate of file, program, or disk Full backup all files in computer Selective backup select which files to back up Three-generation backup preserves three copies of important files In case of system failure or corrupted files, restore files by copying to original location
- 19. Information Privacy What are spyware, adware, and spam? Spyware is program placed on computer without user’s knowledge Adware is a program that displays online advertisements Spam is bogus e-mail message sent to many recipients
- 20. Information Privacy How can you control spam? Collects spam in central location that you can view any time Service that blocks e-mail messages from designated sources E-mail filtering Sometimes removes valid e-mail messages Attempts to remove spam Anti-spam program
- 21. Questions??