What Are Computer Viruses and How do You Protect Your Computer From Them


One of the most destructive forms of malware is the computer virus. This kind of malware can destroy your data, infect your files, and severely damage your computer. Viruses also have the ability to spread on their own and infect other computers. Here’s everything you need to know about computer viruses and what you can do to prevent them.

What is a Computer Virus?

Computervirus LaptopA computer virus is a type of malware with the ability to self-replicate. This means that viruses can spread to other files and programs without the user’s consent.

Computer viruses can spread in a variety of ways. They can hide in email attachments, infected websites, executable files, or pop-up ads. In addition, USB drives and other removable storage devices can contain viruses and spread them to your computer. Some viruses begin replicating as soon as they get onto your device, and other require a trigger for the virus code to activate. Although antivirus software can protect your computer from viruses, its effectiveness is limited. There are now many viruses that can evade antivirus software, which makes detecting the malware more challenging.

Common Types of Viruses

  • Boot Sector Virus: A virus that infects a computer’s master boot record and often spreads through removable storage devices and media. It is usually difficult to remove and often requires the entire hard drive to be reformatted.
  • Overwrite Virus: A virus that infects your files and destroys them. The only way to remove it is to delete all the infected files, which results in the loss of data contained in them. Overwrite viruses most commonly spread through emails.
  • Resident Virus: This kind of virus embeds in the computer’s memory. If the original virus is deleted, a copy of it can remain in the computer’s memory. It can then be activated when your operating system performs certain functions. Since these viruses hide in your RAM, they often go undetected by antivirus software.
  • File-Infecting Virus: A virus that overwrites or inserts infected code into executable files. When the infected file is opened, the virus overwrites or destroys it. File-infecting viruses can also spread to a computer’s operating system or even reformat your hard drive.
  • Macro Virus: A virus written in the same macro language as software programs like Microsoft Office. They embed malicious code in these documents and data files, which begin to run when the files are opened. The virus may then infect all of the user’s documents, altering them or making them unreadable. The virus spreads if the user shares an infected document.

How Common are Viruses?

Viruses are an extremely prevalent form of malware affecting household computers. The Microsoft Security Intelligence Report and Consumer Reports found that in the United States, over 16 million households experienced a computer virus in the past two years. It also estimated that nearly 40% of American households contain devices infected by viruses. In fact, the report stated that 57% of all malware affecting Americans were computer viruses.

In recent years, viruses and other forms of malware have been increasingly targeting governments, healthcare organizations, and businesses. About 75% of American healthcare organizations and 63% of American companies experienced some form of malware attack in 2016.

How Do Viruses Infect Your Computer?

There are many different ways that viruses can infect your computer. Here are some of the most common ways:

Spam Emails And Attachments

Computer viruses often spread by email. This can happen by opening an email attachment, or in some cases by simply viewing the email. Some viruses are also delivered in the HTML body of the email. As a result, many email services disable HTML until you confirm you know the sender.

Instant Messaging

Instant messaging services such as Skype and Facebook Messenger can be used to spread viruses. The most common method is by sending an infected link in a chat message. People are more likely to click on a link from someone they know, and virus developers are well aware of this.

File Sharing Services

Dropbox, SharePoint, and other file-sharing services are another means to spread viruses. If a user uploads an infected file to a file-sharing account, the virus will spread to anyone else with access to that account. Although Google Drive and some other services do scan files for viruses, they only scan files smaller than 25MB.

Fake Antivirus Downloads

Sometimes cybercriminals resort to sending pop-up ads to trick users into thinking their PC has a virus. They insist the user download their antivirus program to remove the virus. However, the antivirus download is a fake one, and it actually infects the user’s computer with a virus.

Unpatched Software

The term unpatched software refers to software that isn’t up-to-date. Developers often release security updates to patch up vulnerabilities in the software, and it is essential to actually install these updates. Cybercriminals often take advantage of these vulnerabilities to infect computers with viruses and other malware.

What Are Some Symptoms of a Computer Virus?

There are certain warning signs that indicate your computer might have a virus. If your computer’s processing speed slows down, or your computer freezes or crashes frequently, it’s a good idea to investigate further. Other possible virus symptoms include pop-up messages about missing files, the appearance of extra files or loss of files, and emails showing up in your sent folder that you didn’t send. You may suddenly experience problems with your hardware or accessories, or see your computer executing commands on its own. These are some common signs that your computer may have a virus.

What Can I Do If My Computer Has a Virus?

There are several steps you should take if your computer has a virus. The steps will differ depending on whether you have a PC or a Mac.

How To Remove A Virus From A PC

  1. Enter Safe Mode: Turn your computer off and then on again and keep pressing the F8 button as it boots up. An Advanced Boot Options menu will appear, and you should select the option Safe Mode with Networking.
  2. Use Your Disk Cleanup Tool: Using this tool will allow you to delete all of your temporary files. To find it, begin by clicking on your Start menu, followed by Programs, Accessories, System Tools, and finally, Disk Cleanup. Select Temporary Files from the File to Delete list, and go ahead and delete them.
  3. Download a Virus Scanner: For extra protection, download a real-time virus scanner such as AVG Antivirus FREE, and an on-demand scanner like Microsoft Safety Scanner.
  4. Run the Scans: Begin by running your on-demand scanner, and then run your real-time scanner. Most likely, one of these programs will be able to detect the virus and remove it. If the scans fail to remove the virus, then you need to remove it manually. You can do this yourself using Windows Registry, but it’s often safer to recruit an IT expert to assist you.

How To Remove a Virus From a Mac

  1. Launch Your Activity Monitor: Use your Activity Monitor to find the compromised app, and search for malware like MacDefender or MacSecurity. When you find the malware, click on Quit Process and exit the Activity Monitor.
  2. Move the Malware into Trash: After closing the Activity Monitor, open your Applications folder. Move the malware into Trash and empty it.
  3. Check For Updates: Check to see if your software and apps are up to date. If there are any OS fixes or Apple Updates, install them immediately.

How Can I Protect My Computer From Viruses?

There are many different steps you can take to protect your computer and devices from viruses and other kinds of malware.

  • Install Antivirus Software: Make sure you install antivirus software from a reputable company and keep it updated. A few Antivirus software include:
      1. McAfee Antivirus
      2. Kaspersky Antivirus
      3. Avira Antivirus
      4. Bitdefender Antivirus
  • Keep Your Computer and Software Updated: Always install computer and software updates when they are available. These updates often fix security vulnerabilities in your operating system and software.
  • Don’t Open Suspicious Emails or Attachments: Delete or mark suspicious emails as spam and don’t open them. You should also select an email provider that scans all attachments before opening them.
  • Install Anti-Malware Apps: In addition to antivirus software, consider using an anti-malware program app. These apps regularly scan your computer for viruses, spyware, and other malware.
  • Install a Firewall: A firewall screens internet and network traffic and can help block potential threats.
  • Turn on Your Browser’s Privacy Settings: Make sure to turn your browser’s privacy settings on, and use a pop-up blocker. You should also clear your cache and browsing history regularly.

Final Thoughts

In recent years, cybercriminals have increasingly been using viruses to target businesses, healthcare organizations, and governments. These viruses can breach data, damage the organizations’ operations, and destroy essential information.

Despite this trend, computer viruses still remain a major cybersecurity threat to personal computer users. They can be extremely destructive and often destroy data or seriously damage computers. For these reasons, computer users need to be aware of this malware threat and take action to protect their devices from viruses.

Tech journalist
Tove has been working for VPNoverview since 2017 as a journalist covering cybersecurity and privacy developments. She has broad experience developing rigorous VPN testing procedures and protocols for our VPN review section and has tested dozens of VPNs over the years.
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  1. I’m sure you won’t get this message, but I’ve been hacked for 3 years or more. I have spent my savings. I’ve bought phone after phone, used different companies and they still find me. I have even got phones not in my name with different Google accounts, but they control my phone settings, steal my data and my home wifi. I’m at my wit’s end. I went months without a phone, because the stress caused heart problems. I had to take my kids phones because of this.

    • We’re sorry to hear you’ve been having these issues for such a long time. In a normal case, we would advise you to set up new and unique passwords for all accounts you’re using, as you can read about here. A full return to factory settings on your devices could help as well, although without knowing how exactly the attacker keeps getting access to your devices this is a mere guess. We would advise you to seek help from someone in your surroundings who is tech-savvy and who can figure out what’s going on without you having to share too much personal information online. Perhaps the articles in the cybercrime and malware sections of our website could give you some further ideas. All the best of luck!

  2. This webpage was by far one of the most interesting and informative sites I have been on in a long time!!! Thanks guys for all the information and links. Happy surfing


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