QUESTION 1
With the aid of examples, discuss each of the five categories of computer viruses. (20 marks)
1. File Infector Viruses: This type of virus attaches itself to executable files, such as .exe or .com files, and spread when the infected file is executed. When the infected file is run, the virus activates and may replicate itself into other files on the system. Examples of file infector viruses include the Cascade Virus and the Jerusalem Virus.
2. Boot Sector Viruses: These viruses infect the master boot record of a hard drive or removable storage media, such as a USB drive, and spread when the infected device is booted up. They can cause the operating system to become unstable or prevent the computer from booting up properly. Examples of boot sector viruses include the Michelangelo Virus and the Stoned Virus.
3. Macro Viruses: Macro viruses infect documents or templates that use macros, such as Microsoft Word or Excel files. When the infected document is opened, the virus can spread to other documents on the system. Macro viruses can be particularly dangerous as they can execute malicious commands without the user's knowledge. An example of a macro virus is the Melissa Virus.
4. Polymorphic Viruses: These viruses are designed to change their appearance each time they infect a new file, making them difficult to detect with traditional antivirus software. Polymorphic viruses have the ability to constantly evolve and create new variants, making them more challenging to remove. Examples of polymorphic viruses include the Elk Cloner Virus and the Marburg Virus.
5. Resident Viruses: Resident viruses embed themselves into the memory of a computer and can remain active even when the infected program is no longer running. This type of virus can monitor and control system functions, making it difficult to detect and remove. Examples of resident viruses include the CMJ Virus and the Randex Virus.
Overall, each category of computer virus poses a unique threat to computer systems and can cause a range of symptoms, from minor inconveniences to catastrophic system failures. It is important for users to have up-to-date antivirus software and practice safe browsing habits to protect against these threats.