Hello friends, Today I will share top 20 most common types of computer viruses. These computer viruses/worms are easily found on the internet. They can harm your computer directly delete files or corrupt your Hard Disk. I will share several names of computer viruses.
What is Computer Virus and its types
In a digital world, viruses are miniature software programs designed to malfunction the operation system of computers while spreading from one device to another. A virus can corrupt files, use your email or social networking account to spread, and even erase all the data from your hard disk automatically. There are several types of computer viruses present these days.
The computer virus is usually spread through email attachments, instant messages, or direct connection with infected hard drives. They can be hidden in attachments of greeting cards, funny images, or latest software files. Computer viruses also infect through cloaked downloads from the Internet. Instead of sharing actual files many websites just upload virus programs describing them as free software installation files. Remember virus can be any form. I would suggest you to read this complete guide on types of computer viruses.
Types of Computer Viruses
These viruses are very dangerous and can harm instantly your PC/Laptops. I have shared all the important names of computer viruses. All these are different types of computer viruses which have the capacity to harm or even destroy your computer. Read the virus description and identify infected files/folders on your PC/Laptops. After your find the file/folder, instantly delete them from your PC. 
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Overwrite Virus
Overwrite virus is characterized by the aspect that it deletes all the data. The only way to get rid of overwrite virus is to delete the infected files immediately and permanently. By which you also lose the data or information contained in those files.
Common examples of overwrite virus are Trj.Reboot, Way, and Trivial.88.D.
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Resident Virus
Resident Virus is one that perpetually lives in the RAM of computers. From there it is capable of overriding and interrupting all the operations executed by the physical memory. Most common signs of the resident virus include corruption of data, random opening and closing of different files, and copying or renaming of files.
Common examples of a resident virus are MrKlunky, Meve, Randex, and CMJ.
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Multipartite Virus
Multipartite viruses are usually spread through media files and hide in the physical memory of computers. Gradually it moves to boot system of the hard disk and infects the files in it and later the whole processing unit in the desktop. A multipartite virus is also known as hybrid virus and requires a complete reset of the system for it to be eradicated.
Common examples of a multipartite virus are GhostBall, Flip, and Invader.
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Directory Virus
Directory or Cluster virus changes the address which indicates the location of any file. Sometimes by opening a file with .com or .exe extensions. You are actually executing a virus file while the original file has been moved by the directory virus. Once infected it is impossible to locate the infected files.
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Direct Action Virus
The primary purpose of direct action viruses is to copy and take action when a program is executed. When the specific condition of this virus is met it infects the files in the directory in which it is located. Direct action virus is mostly located in root directories of the hard drive and carries out its operation when the computer is started.
Common examples of direct action virus are Randex, CMJ, and Meve.
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Non-resident Virus
Non-resident viruses are a bit similar to resident viruses in using replication of program modules. In addition to that, it also works as a finder module that can infect files when it finds one.
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Boot Virus
These types of viruses affect the boot system of hard drives. It is a vital part in which all the information on the disk is stored with a program that is used to boot the computer from the disk. The best way to avoid boot virus is to make sure no unknown storage device is connected while starting the computer. Using write-protected hard disks can also help evade boot virus attacks.
Common examples of boot virus are AntiEXE and Polyboot.B.
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FAT Virus
FAT (File Allocation Table) viruses are a part of disk used in transmitting data and play a crucial role in normal functioning of computers. These virus attacks can prevent you from accessing certain parts of the drive where important files might have been stored. The damage caused by a FAT virus is permanent and non-reversible.
Read more: Top 10 Best Free Antivirus for Windows 7 – Download Free Antivirus of 2017
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Polymorphic Virus
Polymorphic viruses use algorithms and encryption keys to encode themselves differently each time they infect a new system. This makes it almost impossible for anti-virus programs to find them using signature or string searches. Polymorphic Virus also enables them to generate innumerable copies of themselves and spread faster.
Common examples of polymorphic viruses include Tuareg, Marburg, Elkern, and Satan Bug.
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Macro Virus
Macro viruses attack and corrupt files which are created using programs or applications containing macros. These mini-programs actually help the user by carrying out a series of operations as a single one. This saves the users from having to perform them one by one.
Common examples of macro viruses include Melissa.A, O97M/Y2K, and Relax.
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Email Virus
Email viruses are sort of macro virus only. It usually infects computers when it is opened by the recipients. For example, the user might be asked to download a gift voucher attached to the mail. And the rest doesn’t need to be said. The “gift vouchers” always turn out to email viruses sent to infect your computer.
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Companion Virus
Companion viruses are a type of file infector viruses like resident and direct action virus types. These are called “companion viruses” because once they infiltrate the computer system they start “accompanying” files that already exist in the system. To make it simple, we can say that in order to carry out their functions, companion viruses wait in the physical memory for a program to be run and then latches onto it.
Some examples of companion virus are Stator, Terrax.1069, and Asimov.1539.
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File Infectors
Like directory virus, file infectors also attack programs files with .exe and .com extensions. When one of these types of programs is run by the user, file infectors get activated and cause the damage they are programmed to do. Most of the virus usually detected in home networks are of this nature and can be further classified on the basis of function they are encoded to carry out.
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Encrypted Virus
Encrypted viruses are the type of virus that contains malicious codes for decrypting modules. They use encrypted codes that make basic anti-virus software programs impossible to detect them. Even advanced antivirus software can detect them only when they decrypt to spread to other computers.
Common examples of encrypted viruses are Cascade 1701, W95/Silcer, and W95/Resur10.
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Stealth Virus
Stealth virus is a special type of virus that tries to trick antivirus software programs by diverting its requests and messages from the user. It also has the capacity to conceal itself from basic anti-virus applications.
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Network Virus
Network viruses use internet and LAN (Local Area Networks) to spread its infectivity. They usually multiply through shared network connections like shared folders and drives. When a network virus infects one computer, it searches for network connection to find new potential preys. Once the virus finishes corrupting the data in a computer. It moves on to the next one and repeats the cycle.
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Sparse Infectors
A virus must avoid detection at early stages in order to spread effectively. To minimize the chances of its detection by antivirus programs a virus can use numerous methods. For example, it might only affect every 10th time a file is executed. Or only affect files being executed for a specific period of time or files with names beginning with a certain letter of the alphabet. This is what sparse infectors do. Often attached with deadly viruses, sparse infectors help them avoid being discovered at early stages.
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Logic Bombs
Logic bombs are not really considered as a virus because they don’t spread by multiplying. In fact, they aren’t even separate programs but rather disguise themselves with fragments of other programs. Their purpose is to corrupt and delete data on the computer when certain circumstances are met. These bombs stay undetected until launched so the results can be extremely destructive.
Read more: How To Remove Shortcut Virus From Pendrive Permanently – Easy Method
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Cavity Virus
Unlike most virus programs that go easy when infecting files, cavity virus takes the clever way. Many application and program files have vacant spaces in them. It vacant spaces can be used to hide viruses. A cavity virus installs itself in the spaces while not affecting the program itself. The basic point of this kind of virus is that it doesn’t increase the size of programs and can avoid detection from anti-virus software.
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Worms
A worm is not precisely a virus, though it has the ability to spread by self-replicating itself and can cause adverse effects on your system.
Common examples of worms are Mapson, Trile.C, and PSWBugbear.B.
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Trojan Horses
Trojan Horses or Trojans are also not actually a virus but are capable of corrupting files and data. Though, unlike worms, they do not spread by multiplying or infecting through drives.
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Web Scripting Virus
Many websites include composite codes to create appealing and interactive content. These codes are often used to spread undesirable programs into the computers. Their main source is infested browsers and web pages.
A common example of web scripting virus is JS.Fortnight.
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Browser Hijacker
Browser hijackers can cause entering any particular internet URL bounce the user to multiple websites. These hijackers can attach themselves to toolbars of browsers and free download options. A good way to avoid them is to stay away from appealing free downloads and extensions. Reliable antivirus programs can also detect them quite easily.
Conclusion
These viruses are very dangerous and can harm instantly your PC/Laptops. I have shared all the types of computer viruses. You can check the virus description and later remove that from your PC/computer. Do share this article and help your friends understand types of computer viruses and delete all infected files.
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