Types of computer virues

   A computer virus is a program designed to harm or cause harm on an infected computer. Its spreads through e-mail attachments, portable devices, websites containing malicious scripts and file downloads. A computer virus attaches itself to the host files and always activate whenever you open the infected files. The virus can replicate itself and then infect the other files on your computer causing more damage. Below is a list of different types of computer viruses and what they do.

1. Macro viruses

                       These viruses infect the files created using some applications or programs that contain macros such as doc, PPS, x ls and M db. They automatically infect the files with macros and also templates and documents that are contained in the file. They hide in documents shared through e-mail and networks.

Macro viruses include:

•     Relax

•     blabs

•     Melissa.A

•     097M/Y2K

2. Memory Resident Viruses

                   They usually fix themselves inside the computer memory. They get activated every time the OS runs and end up infecting other opened files. They hide in RAM.

Memory Resident Viruses Include:

•     CM J

•     meve

•     rand ex

•     mrklunky

3.Overwrite Viruses

            These types of viruses delete any information in a file they infect, leaving them partially or completely useless once they are infected. Once in the computer, they replaces all the file content but the file size doesn’t change.

Overwrite Viruses Include:

•     Tr j.Reboot

•     way

•     trivial.88.D

4. Direct Action Viruses

           These viruses mainly replicate or take action once they are executed. When a certain condition is met, the viruses will act by infecting the files in the directory or the folder specified in the AUTO EXEC.BAT. The viruses are generally found in the hard disk’s root directory, but they keep on changing location.

5.Directory Virus

          Also known as cluster virus or file system virus. They infect the computer’s directory by changing the path indicating file location. They are usually located in the disk but affect the entire directory.

Directory Viruses Include:

•     dir-2 virus

 6.Web Scripting Virus

          Most web pages include some complex codes in order to create an interactive and interesting content. Such a code is often exploited to cause certain undesirable actions. They mostly originate from the infected web pages or browsers.

Web Scripting Viruses Include:

•     JS.Fortnight – a virus that spreads via malicious emails.

7.Multipartite Virus

           These type of viruses spread in many different ways. Their actions vary depending on the OS installed and presence of certain files. They tend to hide in the computer’s memory but do not infect the hard disk.

Multiparty Viruses Include:

•     flip

•     invader

•     tequila

8. FAT Viruses

         These lardy viruses attack the file allocation table (FAT) which is the disc part used to store every information about the available space, location of files, unusable space etc.

FAT Viruses Include:

•     the link virus

9. Companion Viruses

        These types of viruses infect files just like the direct action and the resident types. Once inside the computer, they ‘accompany’ other existing files.

Companion Viruses Include:

•     Asimov.1539

•     stator and terrax.1069

10.Polymorphic Virus

           They encode or encrypt themselves in a different way every time they infect your computer. They use different encryption and algorithms. This makes it difficult for the antivirus software to locate them using signature or string searches (since they are very different in each encryption).

Polymorphic Viruses Include:

•     Mar burg

•     Tuareg

•     Satan bug

•     elkern

11. Trojans

Trojans can illegally trace important login details of users online. For example E-Banking is very common among users, therefore, vulnerability of tracing your login details whenever your PC is working without any strong powerful antivirus installed.

12.Email Virus

          This is a virus spread via an email. Such a virus will hide in an email and when the recipient opens the mail.