How computer viruses spread and how to avoid them

With so many people in the world using more than one device, both for personal and work purposes, it has never been more likely that people will encounter some kind of computer virus. These can impact a machine in many ways, but we seem to associate them most with taking over screens and displaying annoying popups.

However you're alerted to the presence of a virus, you need to remove it as soon as possible. The longer you leave it the more damage it can do. After that, you may then want to ask how it got there in the first place.

Computer viruses are similar to biological viruses, in that they can spread from one computer to another relatively quickly. Having an understanding of how they spread is one of the first steps to preventing you from having an infected device.

What are computer viruses?

Computer viruses are, unfortunately, a man-made problem. They're a type of malicious code specifically designed to alter how a computer works. The capability to spread from one machine to another is also a fundamental part of their design, where a virus attaches itself to a host program and executes the new code through the host.

The malevolent use cases for viruses are only limited to people's imaginations and often the underlying code of a virus can be tweaked and used for many different purposes. A virus can cause significant damage to the computer’s software, destroy data or even encrypt data. Hackers use them to gain access into wider systems, cause network disruption and also for financial gains.

Three common ways computer viruses spread

Computer viruses aren’t random. You can’t just turn on your computer and suddenly have a virus for no reason. Somehow, it had to be installed on your machine, and there are three primary ways this happens.

Infected email attachments

Computer viruses can’t infect your computer through a text-only email. However, if an email includes an attachment or clickable link, those could be vehicles for a virus. If you open an attachment or click a link, your computer downloads that information. If that attachment or link includes a virus, your computer is now infected.

Hackers can sometimes mask malicious links as other things, like images or text, that bait you into clicking or are so large you click them inadvertently.

Removable Media

When you attach a memory card, USB flash drive, external hard drive or any other kind of removable media to your system, you face the potential of importing a virus. If a hacker attached a virus to a program or file on the drive, you’ll also install the virus when you plug in the media.

Internet Downloads

When you download anything off of the internet, you’re installing new files and code on your computer. Many viruses are attached to freebie downloads, including free software trials or, ironically, free virus protection.

Anything downloaded illegally, like music, movies or games, is an easy target for hackers because you’ll probably be getting that file in a peer-to-peer format. Even your antivirus program may not be able to stop it.

How to protect yourself from computer viruses

Viruses are a fact of life when operating a computer. Like it or not, you must be on guard against them at all times.

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While there may not be a single foolproof way to safeguard your machine against all possible viruses, there are a few things you can do to keep the odds in your favor.

• Always have antivirus protection on your computer. Always keep your antivirus on and make sure you’re getting updates regularly so you’ll be defended against the latest known viruses. With a little research, you can find the best antivirus software.
• Never click on any link or attachment you receive in an email unless you’re absolutely certain it’s from someone you know and trust.
• If your bank or another company you do business with sends you an email asking for personal information, don’t click the link. Instead, open a new window and log in to your account with that company. There’s a good chance it’s a fake email that could steal your information or give your system a virus.
• Scan any removable media before opening any files or programs on it. Your antivirus software can scan and remove viruses from removable media the same way it can your computer.
• Keep your email safety features on.
• Stay up to date with your computer system’s critical updates. Those updates continually plug security holes to protect your system. Set your computer up to update automatically so you don’t have to even think about it.
• Enable your firewall protection. Both Mac and PCs have it, but that doesn’t mean it’s operating. Verify your firewall is active and protecting your computer.
• Back up your computer. If the unthinkable happens, a backup of your computer on an external hard drive or in the cloud allows you to recover what you need if a virus obliterates your machine.