Key Points
- Computer viruses are a type of malware.
- Computer viruses spread by self-replicating into code and programs.
- Most types of computer viruses spread through malicious links and attachments.
What is a Computer Virus?
Computer viruses are a form of malware, but they act differently from most types of exploits. They are different because of the way they spread. Most computer viruses spread by moving from one device to another. They self-replicate into code and insert themselves into programs.
While viruses spread mainly through infected email attachments in the past, today’s computer viruses are a little more sneaky. They can duplicate themselves and infect shared links, images, videos, USB sticks, and shared documents. Computer viruses can even infect an entire internet network. However, the most common way computer viruses are spread is still through email.
While they spread in different ways, how computer viruses affect devices will vary on their type. Some can completely erase files, while others steal your personal information. Most viruses can have damaging, if not a permanent, effect on your system, often requiring a lot of work to undo.
How Will I Know If My Computer Has a Virus?
Unfortunately, you won’t always know if your computer has become infected with something malicious. You may notice that your default browser or homepage has changed. Or you may notice that suddenly, your files are taking up much more real estate than they used to. While not every virus acts the same, there are a few tell-tale signs of infection.
Common Effects of Computer Viruses
- Repeated crashing or restarting
- A large number of pop-up windows
- Emails sent from your address that you didn’t initiate
- Unexpected changes in your browser settings
- Slow operating speeds
- Programs opening or closing on their own
If you experience any of these effects, we suggest checking your computer or other devices for viruses.
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The 10 Most Common Types of Computer Viruses Today
There are many types of computer viruses today. They originate from all around the world and can infect any machine, be it a Mac or a PC.
We’ve created a list of the most common types of computer viruses you’ll find today. Most of these viruses can be spread easily from an infected device through links and email attachments.
Let’s break them down below.
Trojan Horse Virus
Aptly named, trojan horse viruses are disguised to work like regular programs, files, and software. However, once downloaded, it will share your personal data. Some personal data it will share includes your name, age, address, and bank account information. Unfortunately, this virus will continue to replicate and spread without your interference. For example, some computer viruses need you to click on a link to spread. The trojan doesn’t need you to take action.
Resident Virus
A resident virus will likely spread itself through malicious emails. Once someone opens up a spam email or clicks on a suspicious link, a resident virus will set itself up in computer RAM. Once the virus has made itself at home, it will mess with a computer system’s operations. Unfortunately, you will often be unaware of this.
Resident viruses will also automatically infect software and files, going so far as to attach themselves to antivirus software. If it does get attached to your antivirus software, it can spread every time you run an antivirus check.
Multipartite or Hybrid Virus
A multipartite virus attacks your computer files and the way your computer boots up. It will take up a lot of space in files, which may make it easier to spot. Most of the time, this type of computer virus will spread through infected .exe files. These .exe files are pretty common, often used to install computer software. Unfortunately, multipartite will affect your entire operating system, folders, and programs.
Browser Hijacker Virus
A browser hijacking virus will invade your browser, most likely forcing it to redirect to malicious websites. This type of virus is also often called a browser redirect virus. If a browser hijacker has infected your system, you will probably notice a plethora of annoying pop-ups. You may also notice that your browser homepage has suddenly changed.
Overwrite Virus
An overwrite virus does its dirty work by writing over the original file code. It will permanently erase files as well. Sadly, there is no hope of recovery of these files once you’ve accidentally downloaded the overwrite virus. Also, an overwrite virus often infects a computer via infected websites.
Network Virus
A new type of computer virus, called a network virus, spreads itself through an infected internet network. This virus will attack a trusted connection and move from one computer to another through their memory disguised as network packets. Once a network is infected, it will access and damage all files located on that network.
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Polymorphic Virus
A polymorphic virus will delete information while sharing files downloaded in dangerous emails and infected attachments. It can even attack a computer once someone opens an email without anyone needing to click on anything. Unfortunately, this virus works by constantly mutating itself as it moves, which can make it hard to detect. However, it does always perform the same action, keeping the same routine.
Macro Virus
Named after the code that it’s written in, a macro virus will work by spreading through Microsoft Office files. Macros infect everything from Excel to Word. Also, this virus will increase in size as it infects these files so it may be easier to spot. This computer virus doesn’t just attack Windows machines — it will also attack macOS and Linux.
Boot Sector Virus
People often use the word boot to refer to the action of starting or restarting a computer. So, it’s not a surprise that a boot virus will infect your device’s system startup so severely that a complete reformat of your machine will be necessary. Because the boot sector will spread itself throughout external devices such as a USB stick, it may be easier to avoid.
Web Scripting Virus
A web scripting virus will pose as an actual link on a trusted website. But clicking on the link allows the virus to steal personal information on your computer from computer cookies. It often disguises itself in images, videos, and site code. Web scripting viruses will often inundate users with spam.
How to Protect Yourself From Common Computer Viruses
You don’t have to have many technical skills to protect your computer and mobile devices from virus attacks. You just need to take a few steps to help stop viruses from infecting your system. While no method is full-proof, here are some ways you can protect your computer and other devices.
- Use an antivirus and antispyware software.
- Use a firewall.
- Keep your devices and software up to date.
- Choose strong passwords.
- Use two-factor authentication.
- Double-check links before clicking.
- Never open an attachment or click on a link in an email from an unknown sender.
- Shop online using only reputable sites and companies.
- Review your personal and financial information regularly.
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