WHAT ARE COMPUTER VIRUSES;- A computer virus is a malicious piece of computer code designed to spread from device to device. A subset of malware, these self-copying threats are usually designed to damage a device or steal data.


A computer virus is a type of malicious software, or malware, that spreads between computers and causes damage to data and software.



A computer virus is a program which can harm our device and files and infect them for no further use. When a virus program is executed, it replicates itself by modifying other computer programs and instead enters its own coding. This code infects a file or program and if it spreads massively, it may ultimately result in crashing of the device.

Computer viruses aim to disrupt systems, cause major operational issues, and result in data loss and leakage. A key thing to know about computer viruses is that they are designed to spread across programs and systems. Computer viruses typically attach to an executable host file, which results in their viral codes executing when a file is opened. The code then spreads from the document or software it is attached to via networks, drives, file-sharing programs, or infected email attachments.

Some computer viruses are programmed to harm your computer by damaging programs, deleting files, or reformatting the hard drive. Others simply replicate themselves or flood a network with traffic, making it impossible to perform any internet activity. Even less harmful computer viruses can significantly disrupt your system’s performance, sapping computer memory and causing frequent computer crashes.


Even if you’re careful, you can pick up computer viruses through normal Web activities like:

  • Sharing music, files, or photos with other users
  • Visiting an infected website
  • Opening spam email or an email attachment
  • Downloading free games, toolbars, media players and other system utilities
  • Installing mainstream software applications without thoroughly reading license agreements

How do computer viruses spread?

Viruses can be spread several ways, including via networks, discs, email attachments or external storage devices like USB sticks. Since connections between devices were once far more limited than today, early computer viruses were commonly spread through infected floppy disks.

Today, links between internet-enabled devices are for common, providing ample opportunities for viruses to spread. According to the U.S. Cybersecurity and Infrastructure Security Agency, infected email attachments are the most common means of circulating computer viruses. Most, but not all, computer viruses require a user to take some form of action, like enabling “macros” or clicking a link, to spread.


A computer virus will more than likely have an adverse effect on the device it resides on and may be discoverable through common signs of performance loss, including:

Speed of System

A computer system running slower than usual is one of the most common signs that the device has a virus. This includes the system itself running slowly, as well as applications and internet speed suffering. If a computer does not have powerful applications or programs installed and is running slowly, then it may be a sign it is infected with a virus.

Pop-up Windows

Unwanted pop-up windows appearing on a computer or in a web browser are a telltale sign of a computer virus. Unwanted pop-ups are a sign of malware, viruses, or spyware affecting a device.

Programs Self-executing

If computer programs unexpectedly close by themselves, then it is highly likely that the software has been infected with some form of virus or malware. Another indicator of a virus is when applications fail to load when selected from the Start menu or their desktop icon.

Accounts Being Logged Out

Some viruses are designed to affect specific applications, which will either cause them to crash or force the user to automatically log out of the service. Crashing of the Device

System crashes and the computer itself unexpectedly closing down are common indicators of a virus. Computer viruses cause computers to act in a variety of strange ways, which may include opening files by themselves, displaying unusual error messages, or clicking keys at random.

Mass Emails Being Sent from Your Email Account

Computer viruses are commonly spread via email. Hackers can use other people’s email accounts to spread malware and carry out wider cyberattacks. Therefore, if an email account has sent emails in the outbox that a user did not send, then this could be a sign of a computer virus.

Changes to Your Homepage

Any unexpected changes to a computer such as your system’s homepage being amended or any browser settings being updated are signs that a computer virus may be present on the device.

Crashing of the Device

In most cases, if the virus spreads in maximum files and programs, there are chances that the entire device may crash and stop working


Below are explanations of different types of computer viruses:

  1. Boot Sector Virus – It is a type of virus that infects the boot sector of floppy disks or the Master Boot Record (MBR) of hard disks. The Boot sector comprises all the files which are required to start the Operating system of the computer. The virus either overwrites the existing program or copies itself to another part of the disk.
  2. Direct Action Virus – When a virus attaches itself directly to a .exe or .com file and enters the device while its execution is called a Direct Action Virus. If it gets installed in the memory, it keeps itself hidden. It is also known as Non-Resident Virus.
  3. Resident Virus – A virus which saves itself in the memory of the computer and then infects other files and programs when its originating program is no longer working. This virus can easily infect other files because it is hidden in the memory and is hard to be removed from the system.
  4. Multipartite Virus – A virus which can attack both, the boot sector and the executable files of an already infected computer is called a multipartite virus. If a multipartite virus attacks your system, you are at risk of cyber threat.
  5. Overwrite Virus – One of the most harmful viruses, the overwrite virus can completely remove the existing program and replace it with the malicious code by overwriting it. Gradually it can completely replace the host’s programming code with the harmful code.
  6. Polymorphic Virus – Spread through spam and infected websites, the polymorphic virus are file infectors which are complex and are tough to detect. They create a modified or morphed version of the existing program and infect the system and retain the original code.
  7. File Infector Virus – As the name suggests, it first infects a single file and then later spreads itself to other executable files and programs. The main source of this virus are games and word processors.
  8. Space filler Virus – It is a rare type of virus which fills in the empty spaces of a file with viruses. It is known as cavity virus. It will neither affect the size of the file nor can be detected easily.
  9. Macro Virus – A virus written in the same macro language as used in the software program and infects the computer if a word processor file is opened. Mainly the source of such viruses is via emails.


Antiviruses have made great progress in being able to identify and prevent the spread of computer viruses. When a device does become infected, though, installing an antivirus solution is still your best bet for removing it. Once installed, most software will conduct a “scan” for the malicious program. Once located, the antivirus will present options for its removal. If this is not something that can be done automatically, some security vendors offer a technician’s assistance in removing the virus free of charge.

Antivirus is a kind of software used to prevent, scan, detect and delete viruses from a computer. Once installed, most antivirus software runs automatically in the background to provide real-time protection against virus attacks. for example

  • Bitdefender Internet Security.
  • Norton Security.
  • Comodo Internet Security.
  • Kaspersky
  • AVAST Antivirus
  • AVG Antivirus
  • Avira Antivirus
  • Microsoft Security Essentials
  • Amiti Antivirus
  • Ad-Aware Antivirus


Computer viruses are almost always invisible. Without anti-virus protection, you may not know you have one. This is why it is vital to install anti-virus protection on all your devices.

If your PC has a virus, following these ten simple steps will help you to get rid of it:


Download a virus scanner or complete internet security solution. We recommend Kaspersky Internet Security.


When you are removing a virus from your PC, it is a good idea to disconnect from the internet to prevent further damage: some computer viruses use the internet connection to spread.


To protect your computer while you remove the virus, reboot it in ‘Safe Mode’.

Are you unsure of how to do this?

Here is a simple guide:

  • Turn your computer off and on again
  • When the screen lights, press F8 to bring up the ‘Advanced boot options’ menu
  • Click ‘Safe Mode with Networking’
  • Remain disconnected from the internet


Next, you need to delete any temporary files using ‘Disk Clean Up’.

Here’s how to do this:

  • Click the Windows logo on the right bottom
  • Type “Temporary Files”
  • Choose “Free up disk space by deleting unnecessary files”
  • Find and select “Temporary Internet Files” in the ‘Files to delete’ Disk Cleanup list and click OK
  • Confirm “Delete Files” selection

Some viruses are programmed to initiate when your computer boots up. Deleting temporary files may delete the virus. However, it is not safe to rely on this. To ensure you rid your computer of viruses, it is wise to complete the following steps.


Now it is time to run a virus scan using your chosen anti-virus or internet security software. If you are using Kaspersky Internet Security, select and run ‘Scan’.


If a virus is found, it may affect multiple files. Select ‘Delete’ or ‘Quarantine’ to remove the file(s) and get rid of the virus. Rescan your computer to check there’s no further threats. If threats are found, quarantine or delete the files.


Now that the virus is removed, you can reboot your computer. Simply turn it on as you would normally. It no longer needs to be in ‘Safe Mode’.


To protect your computer from further attack, change all your passwords in case they were compromised. This is only strictly necessary if you have reason to believe your passwords have been captured by malware, but it is better to be safe than sorry.

You can always check the virus’s functionality on your anti-virus vendor’s website or with their technical support team if unsure


Updating your software, browser and operating system will reduce the risk of flaws in old code being exploited by criminals to install malware on your computer.

Is a Trojan a virus?  Trojans can be viruses. A Trojan is a computer program pretending to be something it’s not for the purposes of sneaking onto your computer and delivering some sort of malware. To put it another way, if a virus disguises itself then it’s a Trojan. A Trojan could be a seemingly benign file downloaded off the web or a Word doc attached to an email. Think that movie you downloaded from your favorite P2P sharing site is safe? What about that

“important” tax document from your accountant? Think twice, because they could contain a virus.

Is a worm a virus? worms are not viruses, though the terms are sometimes used interchangeably. Even worse, the terms are sometimes used together in a strange and contradictory word salad; i.e., a “worm virus malware.” It’s either a worm or a virus, but it can’t be both, because worms and viruses refer to two similar but different threats. As mentioned earlier, a virus needs a host system to replicate and some sort of action from a user to spread from one system to the next. A worm, conversely, doesn’t need a host system and is capable of spreading across a network and any systems connected to the network without user action. Once on a system, worms are known to drop malware (often ransomware) or open a backdoor.

Is ransomware a virus? Ransomware can be a virus. Does the virus prevent victims from accessing their system or personal files and demands ransom payment in order to regain access à la ransomware? If so, then it’s a ransomware virus. In fact, the very first ransomware was a virus (more on that later). Nowadays, most ransomware comes as a result of computer worm, capable of spreading from one system to the next and across networks without user action (e.g., WannaCry).

Is a rootkit a virus? rootkits are not viruses. A rootkit is a software package designed to give attackers “root” access or admin access to a given system. Crucially, rootkits cannot self-replicate and don’t spread across systems.

Is a software bug a virus? Software bugs are not viruses. Even though we sometimes refer to a biological virus as a “bug” (e.g., “I caught a stomach bug”), software bugs and viruses are not the same thing. A software bug refers to a flaw or mistake in the computer code that a given software program is made up of. Software bugs can cause programs to behave in ways the software manufacturer never intended. The Y2K bug famously caused programs to display the wrong date, because the programs could only manage dates through the year 1999. After 1999 the year rolled over like the odometer on an old car to 1900. While the Y2K bug was relatively harmless, some software bugs can pose a serious threat to consumers. Cybercriminals can take advantage of bugs in order to gain unauthorized access to a system for the purposes of dropping malware, stealing private information, or opening up a backdoor. This is known as an exploit.