The Different Types of Computer Viruses

types of computer viruses

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.

Macro Viruses

These viruses infect the files created using some applications or programs that contain macros such as doc, pps, xls and mdb. 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
  • bablas
  • Melissa.A
  • 097M/Y2K

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:

  • CMJ
  • meve
  • randex
  • mrklunky

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:

  • Trj.Reboot
  • way
  • trivial.88.D

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 AUTOEXEC.BAT. The viruses are generally found in the hard disk’s root directory, but they keep on changing location.

Direct Action Viruses Include:

  • Vienna virus

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

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.

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.

Multipartite Viruses Include:

  • flip
  • invader
  • tequila

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

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

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:

  • Marburg
  • tuareg
  • Satan bug
  • elkern


This program is very similar to a virus and has the ability to self-replicate leading to negative effects on your computer.

Worm Viruses Include:

  • lovgate.F
  • sobig.D
  • trile. C
  • PSWBugbear.B
  • Mapson


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.

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.

Browser Hijacker

This virus can spread in many different ways including a voluntary download. If infects certain browser functions especially in form of re-directing the user automatically to certain sites. A good example is

Browser Hijackers Include:

  • the cool web search

Boot Infectors

They include the boot sector plus master boot record types. All the viral codes can be separate location; however they infect the hard disks or the floppy.

Boot Infectors Include:

  • the brain virus -it is the very first wild virus to be created.

From what we have seen, the many types of computer viruses and their effects are very harmful and can completely damage your system. Always make sure your system is up to date. Also install antivirus software. The antivirus program protects your computer and the personal information in it.


  1. this is perfect site for students doing computer projects
    short and important informations are given in a good format
    i am satisfied by this site

  2. what are the examples ofweb scripting viruses.

  3. i am not sure which virus i have, but these are the symptons. my computer will at any time restart. i can only open with mozilla firefox. clicking google or internet explorer will restart my computer. also if i click my ‘cleaner’ program, or try to save any photos the computer will restart. any suggestions or solutions to correct this problem would be appreciated.

    • Andrew Palmeroy May 1, 2015 at 2:52 pm

      you have a ghost not a virus

    • i have a idea a you change your window so that last option to resolve your problem.
      thank you

    • I would suggest you get Kapersky Rescue Disk 10.
      This program is installed on a disk or usb, and inserted into the computer before you turn it on.
      The computer will boot from the Kapersky disk, preventing the virus from activating.
      Once on, use the tools to scan your computer for the virus, and then get rid of it.
      I hope this helps if it hasn’t been solved yet.

    • you buy an antivirus and remove the virus. If you can’t buy an antivirus, then activate the microsoft security essentials.

    • Your best bet is to immediately isolate that device. Disconnect all connections to the outside (or internal network), and then boot up in safe mode. You can limit connections w/o pulling plugs by disabling the devices in the Control Panel, but your best bet is to always disconnect the physical connection.

      What you would want to start with in Safe Mode is as other described. Utilize tools to detect the type of infection. IF no results come up (from a reputable scanner), then you would want to look into deeper issues like the worms or viruses that morph or jump around your system. The isolation will ensure you are able to corner the infection, while also ruling out that your machine could simply be taken over by a remote user. If that is the case, no virus scanner will help, as they can potentially already have your authentication info, and can log into your system as a valid user (or they could have reconfigured your device to query their device(s), in a Man-in-the-Middle attack). If either of the latter has occurred, you can detect the initial compromising virus, but you would need to check your router/modem settings (to ensure correct DNS and routing settings, not some unknown server addresses), and look for a good network monitor for intrusion detection.

      Most large brand scanner suites (McAfee, Norton 360, Kapersky, etc.) come with real-time scanning, network monitoring, vulnerability scanning/patching and many other useful tools in one program interface. So you might want to consider these options if you ever have the problem in the future. I am only posting to possibly give advice, and to help future readers with some tips.

      • **Also, you may want to check your BIOS options, in case you have the “Secure Boot” function on your system. This helps protect from viruses that attack between POST and the operating system startup. Another thing is that many virus scanning software choices include an option to isolate this pre-OS vulnerability.

        I forgot to mention this in my original post.

    • Guyz the best way to clean ur virus is to just nuke it down by reinstalling ur windows. Bt make urself sure to have a backup of it important files.

      • That guy from seinfeild July 5, 2016 at 6:27 pm

        Sorry, some of us prefer to actually fix a problem instead of going nucular as soon as they see a little bug. ;P

  4. that’s good explanation

  5. is comp virus create itself or we create it

    • A person must create a virus. Humans haven’t gone to that level of artificial intelligence where a virus can create itself.

      • i keep getting sites randomly opening. what type of virus is dis?

        • These pop-up ads are mainly adwares. They are secretly in advertisements and other advertising websites, but they may affect your computer when opened. I suggest to close this immediately, but search engines like Google can block these malicious pop-up ads.

        • Can some plz tell me which virus turn my computer screen to white

    • Many rumors say that it(virus) just made itself, but actually the answer is no. Hackers, are the most main source of these different viruses, which they secretly hide it in an app then when a user installed this on a computer, the virus then starts spreding.(depends on what type)This will continue spreading in external storages and even other computers.

  6. I am satisfied. But my system always read memory capacity during booting process. How can i fix the problem?

    • Well, research if the booting process of a computer includes the reading of memory capacity. If it doesnt include, it doesnt matter as long as there is no strong virus manipulating it. Try downloading Avast! Antivirus and then activate the feature “Scan during boot” in order to find out if there is a virus or not, or it affects your computer

  7. It worked

  8. Ur works are great please keep this up…..cos i personaly find this websit important and useful.

  9. I like how things are been defined with their examples attached to them.
    Go ahead and educate us for the best.

  10. I am facing a problem of sending any types file from my computer to any pendrive or mobile,when i am trying to sending,it is asking the administrative permission,though i am clicking on continue it is showing me the same window and i can’t transfer anything.please provide any suggestion or solution to eliminate the problem.

    • From over 22 million viruses,well,it might be a virus,or not. That happened to me one time on a computer in our, well,computer room. A quick solution to that problem is to send it the other way, like through an app or email. If the solution above still doesnt work, restart your PC and install an antivirus app on your computer than scan the whole pc. That might help.

    • And let me add. That problem may be caused by multiple clicking a button, which the one in your problem, the send button. That triggered the multiple windows. Or maybe your computer is old school and had outdated software or laggy one. Confer my first reply to fix it.

  11. Mikatakuzu Dragneel August 12, 2015 at 11:16 am

    Ways to remove a virus:
    1. Antivirus
    2. Manually
    3. Refresh your computer(This thing is useful against most types of viruses, Because it deletes all the programs you currently have installed and keeps the neccesary stuff needed to run the OS and certain programs that you would usually find on a newly-bought computer)

  12. Our class was making a power point about computer viruses, and we need to include a sound file on said power point. One kid decided to use the JOHN CENA theme song. lets just say our teacher didn’t like it, and we got yelled at. This site is 8 outta 8 m8, i r8.

  13. i have a virus myself and trying to figure out which it is… im using mcafee and norton to try to find it and so far nothing. its a passive one thats for sure.

    • Do these have unusual names and has a faded logo of a saved file of yours? Well, these are not viruses when these popular antivirus softwares like Norton scanned the file and detected no signs of viruses. Regularly check your antivirus program for some updates on virus definition and then scan again. If the scan didnt detect a virus, try deleting the “virus” file. If it doesnt delete automatically and still prevail, sometimes these delete someday. If still not, report it to a virus lab website so that they can study it furthere.

  14. I have personally benefit from this as computer student, but please I need ur help i have problem in my computer when ever I boot it, it can’t show any Light only screen, what should da problem be?

  15. i believe we all know how viruses spread apart from the following ways 1.networks files system 2.internet download 3.removable disks etc can you gays give us other ways of virus transmition

  16. I have a problem in my PC it’s Getting very slow when I m doing some project on my PC

    • There is a slight chance that you have a virus during your work. It is naturally caused by a slow computer, or because of multiple antivirus installed on your computer. Try to scan to figure out what virus is it.

  17. I sheerly appreciat this website for its efficient information. It has asisted me alot. Keep it up, and update it every time because technology changes every day. For Ngundaa, an IT learner its TOOODLES.

  18. are there any viruses that can be found in cell phone

  19. Aren’t we missing a few others?? *

  20. what example of macro virus

  21. wheres the Logic bomb virus? i did’nt see it

  22. I have to prepare a presentation on virus and antivirus .I have got article on that but yet I don’t got types of virus and antivirus clearly.please help me in this matter.

  23. Vijay varghese May 4, 2016 at 3:06 pm

    Really cool i like batch virus
    Gust a click to exicute

  24. Hello, thanks for the information. But how to recover my PC lost all my data because of a Virus that I can’t even explain. From Kampala-Uganda.

  25. Debajyoti Senapati May 17, 2016 at 4:20 am

    very useful for me, Thanks!!!

  26. Guys please can we have a Whats app group for computer (it world wide) & computer problem dealers.
    I’m impressed with above cor operation.

    it’s just suggestions.

  27. This is best way to provide a little bit knowledge of virus we generally heard about virus but don’t know what type of virus is it and download or buy the software anti virus.
    I also asked one question that is it really anti virus worked when we take from another computer through pen drive or download from net.
    As my opinion it doesn’t work but I need our suggestion . Please reply it.

  28. My name is Gift Imiefoh, I bought a computer system nd its about a year old nw..pls advice me on the types of anti virus to use on my windows 2007 system..

  29. You hav3 to download Ghostbusters movie and then problems will be solved…lol😂😂😂

  30. Ths was a very useful lecture for me, also fa people who don’t have a basic idea on’ what are computer viruses are’ then this will be very informative…

  31. I got a virus that a black screen appears while its running and only the mouse is visible. What type of virus is this?

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