What Are Computer Worms And How To Prevent Them

By   Adeola Adegunwa
Writer , Informationsecuritybuzz | Apr 16, 2023 10:41 pm PST

Have you ever heard of computer worms? These malicious programs can cause havoc on your computer system and compromise your data. In the world of cybersecurity, computer worms are a serious threat. They are malware that spreads through networks, infecting computers and causing damage to files and software. The first computer worm was created in the early 1980s, and since then, they have evolved to become more sophisticated and challenging to detect.

The word “worm” can evoke various thoughts, such as chewy candies, invertebrate animals, or malware in computing. Computer worms lack a backbone and rely on deceptive tactics to infect hosts. They exhibit a destructive nature and warrant further examination. Despite the advancements in cybersecurity technology, computer worms remain a significant problem for individuals and businesses.

In this article, we will dig deep into computer worms, how they work, their types, examples, and what you can do to protect yourself from these dangerous programs.

History Of Computer Worms

The Worm also referred to as the Morris Worm, had a real-world impact in 1988. Created by Robert Morris, it exploited email protocol vulnerabilities. The goal was to raise awareness and highlight network weaknesses.

The Morris worm spread faster than expected and infected 6,000 out of 60,000 internet-connected computers in 24 hours. A programming mistake caused the program to replicate and render infected computers unusable.

While the worm achieved its goal of exposing network weaknesses and gaining media attention, it caused significant financial damage. The U.S. Government Accountability Office estimates the damage up to $10 million.

What Are Computer Worms

Malware that can spread between computers without human activation is known as computer worms. It often spreads through a network connection. It is related to Trojan horse malware but requires different methods of propagation.

Trojans utilize deception and social engineering tactics to persuade individuals to execute them. One common approach involves masquerading as legitimate software. Worms are considered a type of Trojan as they often depend on social engineering methods to infiltrate systems.

Features Of Computer Worms

Computer worms are a form of harmful software that can self-replicate and distribute through networks without user input. The following are typical characteristics of computer worms:

  • Computer worms can replicate themselves and spread to other computers automatically without user intervention.
  • Worms can spread through computer networks by taking advantage of network software weaknesses or utilizing social engineering methods to deceive users into downloading and running the worm.
  • Worms have the potential to consume substantial system resources, including memory and bandwidth, which may lead to system slowdowns or crashes.
  • Worms can execute harmful actions, including data theft, file deletion, and launching DDoS attacks.
  • Certain worms can conceal themselves within an infected system, making it difficult for security measures and anti-virus software to detect.
  • Worms may try to remain on the infected system to maintain their malicious activities even after the initial infection has been resolved.

Examples Of Computer Worms

Throughout history, certain worms have had a significant impact, resulting in billions of dollars in damages. The following is a concise list of some of the most notorious ones.

  • The Morris Worm also called the Internet Worm, gained media attention as one of the earliest computer worms to spread through the Internet.
  • Bagle, a mass-mailing worm, was known by names such as Beagle, Mitglieder, and Lodeight and had numerous variations.
  • Blaster, a worm also referred to as MSBlast, Lovesan, and Lovsan, targeted computers operating on Windows XP and Windows 2000.
  • The worm known as Conficker or Downup, Downadup, and Kido utilized Windows vulnerabilities to spread and infect millions of computers in over one hundred countries.
  • The ILOVEYOU worm caused significant damage to computer systems worldwide, infecting millions of devices and resulting in billions of dollars in losses.
  • Mydoom was recorded as the email worm with the highest rate of spread in 2004, disrupting email communication by transmitting unwanted messages among computer systems.
  • Ryuk is a type of ransomware that has worm-like features despite not always having been so.
  • The SQL Slammer worm caused denial-of-service attacks on some Internet hosts, slowing Internet traffic and gaining notoriety.
  • The Storm Worm used social engineering tactics by spreading false reports of a severe storm to infect compromised computers with botnets.
  • Experts speculate that the Stuxnet worm was developed over several years to carry out a cyberattack.

Do Computer Worms Spread?

Fraudulent emails, known as phishing, can contain corrupt attachments or links that may infect users with worms. It is important to be cautious of these emails, as they may appear authentic.

  • Targeted phishing attempts, known as spear-phishing, can potentially carry harmful malware such as ransomware crypto worms.
  • Worms are capable of self-replicating across networks through shared access.
  • Certain types of worms can enter a system by exploiting weaknesses in the software.
  • P2P file networks have the potential to transmit malware, such as worms.
  • Specific types of worms have impacted social networks, such as MySpace.
  • Malware, including worms, can be transmitted through text messages and instant messaging platforms like Internet Relay Chat (IRC).
  • External storage devices are susceptible to worm infections, including USB sticks and external hard drives.

What Are The Functions Of Computer Worms?

After a computer worm infiltrates a computer’s defenses, it has the capability to execute various harmful actions.

  • Avoid installing additional malicious software such as spyware or ransomware.
  • Consume bandwidth.
  • Delete files.
  • Overload networks.
  • Steal data.
  • Open a backdoor.
  • Deplete hard drive space.

Computer Worms vs. Viruses

Malware is harmful software that can harm computers and networks. Computer worms and viruses are two types of malware. Computer worms are self-replicating programs that spread automatically through networks and the internet. They can install a backdoor, which gives attackers access to a victim’s system without their knowledge.

Computer viruses replicate themselves but require user action to spread to other programs or systems. They rely on users clicking on infected emails, downloads, files, and websites. Unlike worms, viruses must be executed manually by a user before spreading. Once active, malicious software operates in the background, causing slow network performance and potential outcomes like data corruption or identity theft.

Types Of Computer Worms

There exist various types of computer worms that are malicious.

Email worms

Email worms spread by sending messages containing a harmful executable file that infects the recipient’s system upon opening and are sent out indiscriminately from a user’s contact list. In order to succeed, email worms frequently employ phishing and social engineering techniques to trick people into opening the attached file.

File-sharing worms

File-sharing worms have the ability to duplicate themselves in shared folders and propagate through peer-to-peer file-sharing networks. It is not uncommon for worm creators to conceal these harmful programs as media files.

The Stuxnet computer worm is comprised of two components. One is a worm that spreads malware through infected USB devices. To succeed, email worms frequently employ phishing and social engineering techniques to trick people into opening the attached file. It is expected to be one of history’s most notorious computer worms.

File-sharing worms have been known to specifically target industrial environments such as power utilities, water supply services, and sewage plants.


Cryptoworms function by encrypting data on the victim’s system, and can be utilized by perpetrators in ransomware attacks, where they demand payment from the victim in exchange for a decryption key to recover the files.

Internet worms

Certain computer worms have a tendency to aim at widely used websites with insufficient security measures. In the event of successfully infecting the site, they are able to infect any computer that accesses it. Internet worms can spread to other devices connected to the infected computer through internet and private network connections.

Instant messaging worms

Instant messaging worms are similar to email worms in that they spread through attachments or links and infect the user’s contact list, but they arrive via instant message on a chat service instead of email.

If the worm has not yet had the opportunity to duplicate itself onto the device, the user may consider altering the password on the chat service account as a preventative measure against further propagation.

Preventing Computer Worms

When receiving email attachments or links, be cautious. Avoid opening them if they are from an unknown sender. They may be phishing scams or contain malware. To ensure its legitimacy, scan the email or file using your antivirus before opening.

  • It is advised not to click on pop-up ads while browsing, as they may contain adware that can infect legitimate websites and devices. An example of common adware is an advertisement claiming a prize or virus on the computer or device.
  • When downloading files through peer-to-peer platforms, it is recommended to exercise caution and avoid downloading from unknown sources. However, if it is necessary to use torrenting, it is advisable to use a VPN.
  • It is recommended to regularly update software to eliminate potential vulnerabilities. Enabling automatic updates, if available, is also advised.
  • It is recommended to update passwords and avoid using default credentials, especially for router configuration, to prevent infection from worms. A password strength test and guide are available for creating stronger passwords.
  • It is recommended to encrypt essential files to safeguard sensitive data on devices and prevent loss in the event of malware infections.


Computer worms are one of the more intriguing types of harmful software (or malware), partly because they don’t harm machines. Worms are categorized as malware, nevertheless, because any incursion into a computer can potentially harm it someday. Worms are distinguishable from computer viruses, the most well-known type of malware, because they replicate themselves. In other words, they can be transmitted to someone else without needing to be physically disseminated by a person. A worm’s only purpose is to spread to as many computers as possible without affecting their functionality, unlike a virus’s desire to harm all systems it comes into contact with.

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