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What Is a Worm? | All You Need to Know About This Type of Malware and Its Removal

Has your computer system or have some tasks stopped operating? Is it possible that your computer is suffering from a worm infection?

Key Takeaways

  • A computer worm is a type of malware whose primary function is to self-replicate and infect other computers while remaining active on infected systems.
  • Today, USB drives are a common vector for computer worms, as are internet activities such as email, chat and web surfing.
  • Removing a computer worm can be difficult. In extreme cases, the system might need to be reformatted, requiring a user to reinstall all software.
  • Good cybersecurity hygiene is essential to protect systems from computer worms.

History of Computer Worms

The first computer worm was mentioned 1975 in when it was first used in the novel "The Shockwave Rider." In the novel, the protagonist came up with a worm that would collect data. In the early days, computer scientists would create computer worms to take advantage of system vulnerabilities by multiplying in the background but not damage the computer.

What Is a Computer Worm?

What is a worm? Is it different or related to malware, and what does malware do? A worm is also called malware or a virus, a program whose primary function is to infect other Windows computers and other devices like Chromebooks and Macs, but it remains active on the infected computer. The malware is self-replicating, without human intervention, and it duplicates to spread to uninfected computers. 

A worm doesn't require to attach itself to software or laptops/PCs OS to spread. They can also attach to parts of the system that are automatic and invisible to the user. It is possible for computer worms to hide for an extended period, and you'll only notice them when they attack most of the system. They can even slow down or even stop some operations.

computer worm

So, how do worms work?

How Do Computer Worms Spread In Operating System?

The computer worm spreads from one PC to another without human interaction. All that it requires is for the malicious software to become active in an infected machine.

Computer worm spreads initially when you attach storage media such as a floppy disk to an infected PC.

Today, USB drives are still a common avenue of spreading computer viruses. If your PC is also part of a network, it is also susceptible to worm attacks.

what is a computer worm?

How Do Computer Worms Work?

There are several ways through which computer worms can find their way into your PC. Even computer's operating systems that are renown for their safety, like Linux, suffer from these.

For instance, computer worms can get into your device as parts of the operating system, Instant Messages, or as spam email worms. When you open the malicious attachments or links from users who sent the email, it can automatically download the malicious software to your computer or open a link to malicious computer worms. Once the worm is active, it starts to work on your device without your knowledge.

When the computer worms get into your device, they can take advantage of networking protocols to propagate. The worm can delete files or modify them. The computer worms can also add more malicious program to your PC.

Also, the worm's sole purpose can be to deplete the system resources. As such, the worm will replicate itself repeatedly to deplete the systems in your computer, such as the hard drive, and overload the network.

Apart from depleting the system resources of your PC, the worm can also steal data from your computer. It can also create a backdoor that allows hackers to find their way into your PC and settings.

An email computer worm can work by sending outbound messages to your contact list. The message can include malicious code that will infect the recipient's PC when they open the message.

The computer worms can also disrupt networking by saturating the network links with malicious traffic. Nonetheless, as explained in our AVG payment packages review, the best antiviruses should keep you safe from this issue, providing you stay alert to threats. Unfortunately, as explained in our Lookout and AVG comparison, a basic antivirus payment package such as AVG Antivirus Free probably won't suffice.

Damage a Computer Worm Can Do

By overloading a network that is shared, computernworms can use up bandwidth or occupy space on a hard drive. Along with causing havoc and disrupting system processes, computer worms are also used to install backdoors, steal data, and enable threat operators to take control of a computer and its dedicated system settings

woman using apple laptop

Types of Computer Worms 

  • A bot worm is a type of computer worm that can infect computers and turn them into bots and zombies. The computers are then used in coordinated attacks through botnets
  • Email computer worms function through emails. The IM mails and Instant messaging worms will find exploit your contact lists. They will propagate through instant messaging. If you want to protect your PC, avoid opening email attachments and links on your spam, especially from unknown sources. Email worms will have extensions that will make the recipient think that they are media files. Such extensions include exe, mp4, and avi.
  • Internet worms are entirely independent malicious programs. You will search the internet using infected computers to look for software vulnerabilities. If it sees a vulnerable machine, the worm will infect it.
  • File sharing worms. Do you practice peer-to-peer file sharing? Peer-to-peer file sharing and data transfer are popular among users worldwide. When sharing the worms, you expose your PC to the threat of attack by file-sharing worms. File sharing worms can disguise themselves as double-ended media files

Computer Worm Examples

Some of the most notorious computer worms are:

  • The Morris worm. The Morris worm, named for its creator, Cornell University student Robert Tappan Morris, rapidly infected the limited (by today's standards) computers connected to the internet. An estimated 6,000 machines were rendered inoperable.
  • The ILOVEYOU worm. ILOVEYOU destroyed all kinds of files including photographs, audio files and documents. Affected users who didn't have backup copies lost them permanently. In March 1999, similar to ILOVEYOU, the Melissa virus also replicated itself by using Outlook address books.
  • Stuxnet. Stuxnet reportedly ruined almost one-fifth of Iran's nuclear centrifuges. Targeting industrial control systems, the worm infected over 200,000 computers and caused 1,000 machines to physically degrade.
  • WannaCry. WannaCry is a ransomware worm that spread rapidly through across a number of computer networks in May of 2017. After infecting a Windows computer, it encrypts files on the PC's hard drive, making them impossible for users to access, then demands a ransom payment in bitcoin in order to decrypt them.

Differences Between a Computer Worm and Viruses 

Worms are similar to viruses in several ways. For instance, just like viruses, worms can replicate and spread from one PC to another and over networks. However, they differ from viruses in many ways.

For instance, a Trojan virus requires a host file before it can attack a PC. On the other hand, worms exist as separate entities and don't require a host to infect your hardware. The malicious program doesn't require human activation or activation. 

woman behind the monitor

How to Detect If your Machine has a Computer Worm 

It is not an easy task trying to detect a computer worm on your PC. However, detecting is the first step towards removing the computer worm.

The best way to detect a worm is by recognizing the symptoms of a worm in your PC.

If you suspect a worm infection on your machine, it will help if you run a computer virus scan using your anti malware software. Besides identifying viruses, most antivirus software will also identify different sorts of malware and threats on your gadget.

Apart from running an antivirus scan, you can also lookout for the following symptoms that will indicate the presence of a worm in your PC:

  • Checkout for missing or new files on your PC. If you have a computer worm, it can delete files and replace them on your gadget
  • Check your hard drive space. Computer worms are known for replicating themselves over and over. As such, a worm in your PC can deplete your disk space even when you don't have a lot of files in your storage. Thus, if you notice your disk space being used up, it could be a sign of a computer worm infection
  • A significant change in performance and speed. Are programs in your PC running improperly, or are they crashing unexpectedly? Or has the gadget become sluggish in executing commands and other functions? These could be red flags that your PC is infected with worms
  • Unusual behavior on your PC can also be a sign that your PC is infected with malware. You can start noticing programs that will start or close without your interaction, unusual images, sounds, or messages. Other unusual behaviors can include emails sent to your contact list without your knowledge, warning signs from your antivirus software (see AVG and Bitdefender, or AVG and Kaspersky full review) or operating system, and unfamiliar icons on your PC.
grey laptop and a hand

How to Protect Your Device From Computer Worms Infection

A computer worm infection can be disastrous on your PC. It can lead to the loss of sensitive data and files and make you vulnerable to hackers. As such, you need to ensure optimum antivirus for your device to protect it from worm infection.

So, how do you prevent worms from infecting your devices?

  • Keep the operating system and each antivirus software up to date. The updates reduce the risk of worm infection due to new software vulnerabilities that are discovered. Updates come with new features that enhance internet security, and also they seal loopholes that make you susceptible to infections
  • You should install a dependable anti-virus on your PC (see also how to resolve antivirus uninstall issues). The software will help you in detecting all types of malware and also prevent it from running
  • It will help a lot if you encrypt your files to protect the sensitive data that you have on your PC, mobile devices, and servers
  • Use firewalls to prevent malicious software from accessing your gadget
  • You should take care not to click on malicious links or other email attachments on your email or other messaging apps

How to Remove Computer Worms From Your Devices 

Removing a computer worm from your device may not be the most straightforward task. In extreme cases, you may have to format your PC.

If you identify the computer worm, you can look through tools and instructions to remove the infection.

As mentioned earlier, keeping your operating system and software updated effectively prevents your device from computer worm infection. If you want to install updates on an infected PC, you can download the updates on a separate machine. Save the programs on an external storage device and then reinstall them on the infected machine.

Before you can remove the computer worm, disconnect the PC from any network, wired or wireless, or the internet. If you have any storage devices, remove them, and scan them separately for any computer worm.

After disconnecting from the internet and other networks, carry out the following steps:

  • Update all the anti-virus signatures on your PC
  • Use the up-to-date antivirus software to scan your PC for any computer viruses
  • Use the antivirus software to remove any malware that it finds on your machine, including computer viruses. The anti-virus will also help in cleaning the infected files
  • Lastly, ensure that the operating system and all the program installed in the machine are up to date and patched
two men fixing the pc


Worm computer virus can be disastrous when it gets to your PC. It can steal data and open a backdoor for hackers to access your computer and steal your data. The computer worm will also duplicate itself several times to deplete your PC resources. Thus, it will take up space on your hard drive and also overload your networks. Unlike viruses, worms can exist as separate entities that duplicate and, thus, worms spread to other computers without human interaction.


1. Is a computer worm A virus?

Worms are a type of self-replicating malware (and a type of virus) that infiltrate networks via exploiting vulnerabilities and rapidly spread from PC to PC. As a result, worms are capable of self-propagation and rapid spread – not just locally, but with the potential to disrupt global systems.

2. How do I get rid of worm virus?

If your PC is infected with a virus, the following simple steps will assist you in eliminating it:

  1. Download and install a virus scanner as the first step.
  2. Disconnect from the internet.
  3. Force your PC to restart in safe mode.
  4. Delete any temporary files that have been created.
  5. Scan your PC for viruses using the security software or anti-virus.
  6. Delete or quarantine the virus.

3. Is Trojan Horse A computer virus?

Often disguised as a legitimate program, a Trojan horse or Trojan is a type of malware. Trojans are frequently used by cybercriminals and hackers to gain access to users' computers. Typically, users are duped into downloading and executing Trojans via some form of social engineering.

4. Can antivirus remove worms?

Antivirus software will be unable to remove active worms that have infected the computer. However, the app will inform you of the type of worm that has infected your PC. Make a note of the name of the internet worm that was discovered by your antivirus software during a scan of your PC.

5. How will you protect your computer from viruses?

Eight Tips for Securing Your PC Against Viruses and Malware.

- Maintain an up-to-date version of your app.
- Avoid clicking on links contained within emails.
- Utilize complimentary antivirus program.
- Make a backup of your PC.
- Utilize a secure password.
- Employ a firewall.
- Reduce the number of downloads.
- Utilize a pop-up preventer.

About Dusan Stanar

I'm the founder of VSS Monitoring. I have been both writing and working in technology in a number of roles for dozens of years and wanted to bring my experience online to make it publicly available. Visit https://www.vssmonitoring.com/about-us/ to read more about myself and the rest of the team.

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