What Is A Computer Worm, And How Does It Infect A Computer?

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We're fortunate to have the rest of the world at our fingertips as a modern-day society. We can indulge in our favourite television shows with online streaming. We can catch up with the latest goings-on globally thanks to platforms like Twitter and Facebook. Some have even created a full-time career with just a laptop and an internet connection.

However, the growing number of users online has led to increased cyber-attacks and cybercriminals finding weak spots that exploit the users out of their confidential information.

A computer worm is one of the many nasties that computer users face, and therefore knowing what they are, what types of worms exist and how to avoid them is crucial. In this expert guide, you'll get all the information you need to help protect your computer with antivirus software from the dreaded computer worms.

To Understand How Computer Worms Work, We Need to Look at What a Computer Worm Is

What is a computer worm? Well, it's not like the earthworms you see in the park, that's for sure!

The worm virus definition includes any virus transmitted through software with a vulnerability. However, they can also appear as attachments in spam emails or instant messaging services. You can also find some come in the form of worms in network security breaches.

Once these files have been opened or the software has been compromised, a computer worm can usually find its way into your computer. This is typically a result of a link being clicked to a malicious website, or you've triggered an automatic download of the computer worm virus.

The computer worm will work its way through your computer without the user's knowledge. It can destroy files, steal data and cause a worm infestation by repeatedly copying itself.

Ultimately, it's a headache that no user wants to face.

What are the types of Computer Worms?

It's worth knowing about the different types of worm malware out there. The growth of technology and the improved methods of cyber attacks have led to the creation of more worms.

Email worms that infect via email links

With approximately 306 billion emails sent and received every day worldwide in 2020, email is an attractive channel to take advantage of.

An email virus will typically consist of malicious code that's usually in the form of a link within the body of the email to a file attached to it.

It's straightforward for this type of cyberattack to garner success, especially when the user isn't aware these types of viruses exist.

Worms in file-sharing

File-sharing worms are often disguised as media files, and for the most part, some users will click them out of curiosity.

Worms in file-sharing have been used to target industrial plants, water supply services, and sewage plants in the past.

Computer worms in cryptocurrency (Cryptoworms)

These are a newer type of computer worm due to the growth of cryptocurrency. Cryptoworms have been coined as the future of ransomware. Repurposing ransomware is happening more frequently and will likely continue being used for these computer worms.

General internet worms found on sites

Internet worms generally target popular websites that don't necessarily have the best security. These worms can replicate onto any computer used to access the website. You've got a fast-spreading virus across multiple computers across the internet and local area network connections.

Instant messaging worms

An instant messaging worm is another one that self-replicates malicious code through the instant messaging network. This type of worm will spread through the networks due to any loopholes it finds.

How a Computer Worm Infects a Computer

So how does a worm infect a computer? If you're curious to know how these nasty worms infiltrate your computer systems, then read on!

System entry

A worm will typically spread across a network through your local area network or internet connection. Once these viruses enter your computer's operating system, it's only time before the damage is inflicted.

Computer worms spread via replication

The computer worms spread by replicating themselves and making them a somewhat unstoppable computer virus. By replicating, it can do more damage in a short space of time and result in multiple infected computers.

Worms hide on your PC

These sneaky worms can hide on your PC without any knowledge of them being there. However, there are some signs that your PC has a computer worm. This could be a slow system that keeps crashing, new temporary files or files that are now corrupted.

Infection grows with each replication

As the worm spreads, the infection grows with every replication it makes. From infected files to deleting files completely, every replicated worm will do further damage.

The infection will vary depending on what the computer worm was designed to do

When it comes to your infected computer, the type of worm will depend on what level of infection you get. The Morris worm, for example, infected 10% of the internet and is notably one of the most notorious computer worms to have made such a wide-scale impact.

Preventing Computer Worms on Your PC

Preventing malicious software like computer worms from getting onto your PC is possible with the right protection and due diligence.

Antivirus software

Antivirus software can help eliminate computer worms and keep your PC protected. Antivirus software is affordable and can be purchased to cover multiple devices. So whether that's your desktop PC to your, laptop or mobile phone, using this software is critical.

Routine virus checks

To prevent computer worms, it's a good idea to conduct routine virus checks. This will help avoid this type of malware threat and others from sneaking onto your devices without your knowledge.

Only browse safe websites

When browsing sites, make sure you're aware of the site’s legitimacy. Some will be suspicious immediately, and some not so much. Be sure to check for encrypted services when you're shopping online. Any simple grammatical errors or spelling mistakes will be worth being wary of.

Avoid clicking on suspicious links of any form

Any links that aren't expected or that you're not aware of asking for are to be avoided. This is one of the most common ways a victim can be caught unawares. What might seem relatively harmless is something that is probably just worth ignoring.

How to Recognise Computer Worms & an Example of the Virus

As well as spotting the tell-tale signs of an infected device, some previous computer worm examples are helpful to know. That way, you can spot a worm computer virus before it does severe damage.

ILOVEYOU/Love Letter worm

Devastating worms like the ILOVEYOU worm spread through emails in 2000 and posed as a love letter attachment. As a result, it infected over 10 million computers.

Jerusalem/Blackbox worm

This worm nibbled away at computer resources. Not only does this damage your files, but it's triggered to delete any programs run on Friday the 13th of any year. Ultimately, the files become infected to the point that they grow too large for the computer to handle.


Nimda was one of the first worms to modify existing websites to deliver malicious downloads. These were spread by sending out mass emails and then attacking through local area networks.

There are many similar network worm viruses out there that are worth knowing about. Keeping up to date with the latest methods of malware is helpful for your safety and security online. 

How to Help Protect Against Computer Worms?

As well as the preventative measures that you can take to prevent file sharing worms and other malicious software, there are some additional measures you can take.

Stay up to date with malware methods of attack

Be sure to stay up to date with any malware methods of attack. Some malware methods will evolve and become more refined in their ability to attack the user. Remind yourself how to remove malware from Mac and a PC.

Keep all your software updated

Keeping your programs and software updated will help keep your devices protected. Why? Every program has security patches and updates that help protect the software and your computer from harm.

Use a firewall when browsing online

Finally, where you're able to, install a firewall that you can activate when browsing online. This will help alert you to potentially dangerous sites that you should avoid clicking on.

Final Thoughts

To protect your operating system from these worms and other malware. Whilst these are harder to spot, they are often presented in a way that can be identified and avoided.

With lots of malware threats growing in numbers, it's essential to keep an eye on your devices and protect them as best as possible. That way, you'll avoid becoming another victim!