Computer Viruses: Everything You Need to Know

When brothers Basit and Amjad Farooq Alvi realized that their heart-monitoring software was being pirated, they created ‘Brain’ as a virus designed to affect the illegally copied versions of their software. The brothers quickly became overwhelmed with the calls as computers around the world became infected. Brain was the catalyst that led IBM to create the first anti-virus software for consumers in 1987.

In all, Brain was a harmless virus because all it did was display a message for anyone with a pirated floppy disk. In contrast, Loveletter was a worm virus that took over tens of thousands of Windows computers as it spread via email in an attachment. In the decades since hackers and malicious coders have continued to find new and sneaky ways to access online information.

When you use your computer, you are undoubtedly aware of the potential online threats that exist. This blog will explore what a computer virus is, the many forms of viruses, and how anti-virus can help.

Definition of Computer Virus

At its simplest, a computer virus is a piece of malicious software that is installed on a computer to do something terrible. It got its name because it does more than infect your computer; it replicates and tries to spread to other computers via network connections and the internet. Essentially, a computer virus spreads in the same way medical viruses spread.

Types of Viruses

  • The Resident Virus: This virus only lives to watch the world burn. It infects your computer memory and works to corrupt files and programs. They make your computer run slow. 

  • Direct Action Virus: This virus is a targeted virus that looks to infect a specific .exe file. Another Virus that lives to watch the world burn. They make your computer run slow. 

  • Keylogger Virus: A virus that watches everything you type on your computer and then sends that information to some criminal to sift through. This virus lives to steal your information, such as passwords, usernames, account numbers, and other personal information. 

  • Ransomware: Not considered a virus, ransomware’s goal is to lock and encrypt a computer and require payment to regain access. 

  • Overwrite Virus: The name gives this one away. This virus overwrites everything on your hard drive, including your files, pictures, and programs. 

  • Web Scripting Virus: This virus used to be very common (if you remember a time where browser bars were huge), and pop-ups were viruses directing you to specific sites and collecting your web browsing activities. 


Why do viruses exist?

The first computer virus showed up in 1971 and an experimental piece of software (yes, it started in a lab). The virus was named ‘Creeper System’. It was programmed to see if it could replicate, spread, and fill up a computer's hard drive so it could no longer work. Spoiler alert: It worked, and the computer virus was born.
As viruses evolved, they were simply written to give people a headache by making their computers crash, fail, slow down, and other frustrating behaviors. 
Then along the way, some programmer got the idea that a virus could be used to attack a specific system, say a bank, to overwrite all transactions and balances. These viruses were created to serve a singular purpose, wreak havoc on a particular target. With more evolution and malicious intent, someone got the evil idea that they could potentially spread a virus instead of merely targeting one person.
Today viruses exist because cyber-criminals use viruses as a revenue-generating system. 

How do Viruses infect my computer? 

Viruses are spread from computer to computer via the internet, network connections, and riding along on USB flash drives. Most of the time, viruses come in the form of an executable program that has to be opened by computer users. Recently though, viruses can use many office programs' macros functions to launch once the document is opened. Therefore, we never recommend opening an email attachment sent to you by someone you don't know. Or putting USB drives in your computer if you do not know where it originated.

How does anti-virus software work? 

Anti-virus software exists in a cat-and-mouse environment and uses a blacklist approach to viruses. This method is a very reactive approach because the only way to blacklist a virus is for someone, somewhere, to be infected with the new virus, and it must be reported to the anti-virus software company. Luckily, many legitimate anti-virus software companies spend a lot of time researching to find these new viruses before users are impacted. 

When the anti-virus software developer identifies a new virus, it adds the executable and other key characteristics to the black-list and updates the anti-virus software on your computer. Your computer will then be on the look-out for that executable program and keep it from infecting your computer. This method is both an active scanning approach, which means the software is constantly looking for that virus, and a deep scanning approach, where the software will scan every single file on your PC for anything on its blacklist. 

Preventing viruses

The best approach to prevent a virus is to use a good anti-virus software in conjunction with an alert mind. Ensure your anti-virus software is updated regularly and has scheduled weekly deep scans. You can also up your defense by using an Advanced Threat Protection service from Microsoft 365. And as always keep your files and computer safe by updating your anti-virus software never opening attachments from unknown origins.  
If you are not sure which anti-virus to use or are concerned about your network security, contact our friendly Managed IT Services team. We are here to help!

  Get Help With Your Anti-Virus

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Jason Monroe, Associate Director, Solution Development
Jason M. Monroe

Associate Director, Solution Development

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