Types of computer viruses

 

There are a lot of types of computer viruses such as Memory Resident Virus , Direct Action Viruses , Overwrite Viruses , Boot Sector Virus , Macro Virus , Directory Virus , Polymorphic Virus , Companion Viruses , FAT Virus , Multipartite Virus , Web Scripting Virus , Worms and Trojans .I will discuss some of them :

1 - Memory Resident Virus :

 

This type of virus fixes itself in the computer memory and gets activated whenever the operation system runs and infects the files that are then opened. These viruses hide in the RAM and stay there even after the malignant code is executed. " They get control over the system memory and allocate memory block through which it runs its own code, and executes the code when any function is executed ". (JayashreePakhare,2012 ).

2- Direct Action Viruses:

The purpose of these viruses is to take action and replicate when they are executed. When a specific condition is met, the viruses will go into action and infect files in the directory or folders that are specified in the AUTOEXEC.BAT file path. These batch files are often located in the hard disk's root directory and carries out certain operations when the computer is booted. Find First or Find Next technique is used where the code selects a few files as its victims. It also infects the external devices like pen drives or hard disks by copying itself on them. The viruses keep changing their location into new files whenever the code is executed, but are generally found in the root directory of hard disk. (JayashreePakhare,2012 ).

                                                                                                                                          

3 -Boot sector viruses :

A boot sector virus infects the boot record on floppy disks , hard disks, and also on CD’s and DVD’s. Boot sector viruses do not need to be able to successfully boot the victims' computers to infect them . As a result , even non-bootable media can spread  boot sector viruses. When the infected computers do successfully boot, the boot sector viruses stay in memory and infect floppies and other media when they are written by the infected computer. A boot sector virus has become less common as floppy disks have become rarer. (tech-faq.com, n.d).

 

4 - Multi-partite viruses :

" Multi-partite virus shares the characteristics of more than one virus type. For example, a multi-partite computer viruses might infect both the boot record and program file " . (tech-faq.com, n.d).

 

5 – Worms:

Worms are  programs that make and facilitate the distribution of copies of themselves; for example, from one disk drive to another, or by copying themselves using email or another transport mechanism. " The worms may do damage and compromise the security of the computers . They may arrive by exploitation of a system vulnerability or by clicking on an infected e-mail ". (topchoicereviews.com, n.d ).