A computer virus is generally defined as a program inputted into a computer that allows replication of the program installed. As it replicates, the program intentionally infects the computer, typically without the user knowing about the damage being done. A virus, unlike worms or Trojan horses, needs an aid to transfer them to computers. Viruses usually consume a large amount of computer memory, resulting in system crashes. Viruses are categorized into several parts based on its features.
Macro Viruses
A macro virus, often scripted into common application programs such as Word or Excel, is spread by infecting documents. Macro viruses are known to be platform independent since the virus itself is written in the application’s language and not the operating system. When the application is running, this allows the macro virus to spread amongst the operating systems. Thousands of macro viruses that exists, and each is considered a major threat. Examples of these viruses are: Melissa.A and Bablas. pc.
Network Viruses
Network viruses rapidly spread through a Local Network Area (LAN) and sometimes throughout the Internet. Generally, network viruses multiply through shared resources, i.e., shared drives and folders. When the virus infects a computer, it searches through the network to attack its new potential prey. When the virus finishes infecting that computer, it moves on to the next and the cycle repeats itself. The most dangerous network viruses are Nimda and SQLSlammer.
Logic Bombs
The logic bomb virus is a piece of code that is inputted into a software system. When a certain and specific condition is met, such as clicking on an Internet browser or opening a particular file, the logic bomb virus is set off. Many programmers set the malicious virus off during days such as April Fools Day or Friday the 13th. When the virus is activated, various activities will take place. For example, files are permanently deleted.
Companion Viruses
Companion viruses takes advantage of MS-DOS. This virus creates a new file with typically the .COM extensions, but sometimes the .EXD extension as well. When a user manually types in a program they desire without adding .EXE or any other specific extension, DOS will make the assumption that the user wants the file with the extension that comes first in alphabetical order, thus running the virus. The companion virus is rare among Windows XP computers as this particular operating system does not use the MS-DOS.
Boot Sector Viruses
Boot sector viruses generally hide in the boot sector, either in the bootable disk or the hard drive. Unlike most viruses, this virus does not harm the files in the hard disk, but harms the hard disk itself. Boot sector viruses are uncommon in this day and age because these viruses are spread rapidly via floppy disks, not CD-ROMs.
Multipartite Viruses
Multipartite viruses are spread through infected media and usually hides in the memory. Gradually, the virus moves to the hard drive’s boot sector and infects executable files on the hard drive and later across the computer system.
I have a doubt regarding the computer virus, i.e., trojan horse, root kit , botnet are types of malware or they are virus types. I will be grateful to whoever clarifies me.
“Malware” is the larger category, the other terms define specific types of malware.
Malware is a concatenation of “mal” (which means “bad” in Latin) and “ware” from “software.” Malware, therefore, is any type of bad software.
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