Worms

The term 'worm' here does not mean the creature that is big and can be seen by our eyes like earthworm, tapeworm, etc. but these mean the computer programs that do not destroy data. So if a virus does not destroy data then why to be afraid of worms?


The work of worms is to slow down the operation of the computer. It also slows down the memory of the computer and also slows the operation of the programs whatever being done.

System infectors

The system infector infects application program. These viruses may attach themselves to any executable file, with the extension .BIN, .COM, .EXE, .DRV (driver) and .SYS (device driver). These viruses take control after the initial use of the infected programs. Once the infected program is executed, the virus remains there in the RAM (Random Access Memory), even if the file is closed. When you execute another new file the virus attaches itself from the main memory in the new file. In this way all the files get infected. These types of viruses modify the content of the executable files or they may also overwrite, so it disturbs the file from executing. Some examples of system infectors are .Acid rain, Alien.298, Crazy A, etc.

Multipartite virus

Multipartite viruses have combination features of both boot sector virus and system infectors; they can infect both the application programs and the boot sector of a disk. They infect program files, and when the infected program is executed, these viruses also infect the boot record. When you boot the computer next time, the viruses load in the memory from the boot record and then start infecting other files or programs in the hard drive and the computer. The examples of multipartite viruses are Invader, Flip, Tequila, etc.

Message carrying virus

It does not infect the program and files but sometimes it produces unnecessary messages or pictures on the screen which disturb the computer. It also brings all types of unwanted data in the computer's memory. The message carrying virus is not considered the most powerful virus and thus it is one of the weak viruses known to the technological world. In one sense, this virus is a type of comedy virus.

Boot sector virus

It is developed to destroy or infect the boot sector of the disk where, Master Boot Record (MBR) is stored. MBR is a small program, which is responsible for booting the computer system. This boot sector virus's work is to modify the MBR that prevents anyone from being able to boot or 'start up' the computer from the system disk. By using the infected disk or CD during the booting, such type of viruses transmits automatically in the computer system. The examples of boot sector virus are Danish Boot, Devel 941, Disk Killer, etc.