Computer worms and viruses have been around for decades, but understanding the differences between a computer worm vs. a computer virus remains unclear for many people to this day. Not only do some people use the terms viruses and worms synonymously, but some believe a computer worm is simply one type of computer virus. Consequently, viruses and worms are constantly changing. Technologies are advancing and finding new ways to infiltrate your computer. The number of viruses dropped with increased frequency in 2017, and malware has become a $2 billion industry for hackers.

Viruses and worms belong to a group of malicious entities called “malware.” Although they have many similarities, they also have several key differences that make them stand apart. (A worm is the most similar to a virus, but it has the distinction of being self-replicating). With all of the different malware out there, it can be hard to know what’s what. It is important to know the difference between a virus and a worm because they may need to be dealt with differently.

Virus vs Worm: Side to Side Comparison

VirusWorm
What it issmall software programs code injected into other programs or documentsstandalone programs that exist independently
Spreading speedSlowerFast
FunctionPropagates itself over the internet without any assistance whatsoever and transmit software packages as it moves along its pathspread from one computer to another by exploiting security vulnerabilities in operating systems and applications—and they replicate by sending copies of themselves over networks.
Self-replicationYesNo
SolutionWorms can be detected and removed by the Antivirus and firewall.         Antivirus software is used for protection against viruses.
Block accessNoNo
Initial appearance1970s1970s

Virus vs Worm: Seven Must-Know Facts

  • A computer virus and the idea of a worm came into creation around the same time. However, viruses are generally considered much more damaging because they replicate themselves erratically to “infect” as many systems as possible. On the other hand, Worms stay in one place and don’t attempt to change or infect other systems unless ordered to.
  • Worms are standalone self-replicating programs that can create more worms. Viruses require a host file such as a .jpg, .exe, or .doc to attach themselves to and replicate. A worm’s focus is retrieving a list of email addresses from infected computers and sending itself to them as attachments.
  • Worms and viruses can both cause serious security and privacy issues. A small malware infestation can cause problems with files, programs, and devices. On the other hand, more dangerous infections can take your sensitive personal data, perhaps leading to identity fraud and financial crime.
  • Since they first appeared, worms and viruses have evolved based on technological trends in different waves. Computer viruses have been a part of the collective human psyche for more than 60 years, but what began as cyber vandalism has quickly evolved into cybercrime. Worms, Trojan horses, and viruses are constantly changing. Hackers are driven and astute, always eager to test the limits of connection and code to design new infection tactics. More PoS (point of sale) attacks appear to be in the future of cybercrime, and the latest Moker remote access Trojan may be a good illustration of what’s to come. This recently found malware is tough to detect, delete, and avoids all existing safeguards. Nothing is certain, and both attack and defense thrive on change.
  • John Brunner, an American author, first suggested the concept of self-replicating and self-propagating computer software in the 1970s. During that year, Brunner released “The Shockwave Rider,” a fiction in which a self-replicating malevolent program was referred to as a “worm.”
  • The Morris worm is maybe the most well-known computer worm of all time. It was created in the late 1980s by Cornell University alumni Robert Morris and is thought to have infected one out of every ten internet-connected computers at the time. Thousands of other worms have subsequently appeared, but none have been able to match the Morris worm’s infectivity.
  • MyDoom, a virus that initially appeared in 2004, is thought to be the fastest spreading virus in history. MyDoom was still active in 2019, according to Unit 42’s cybersecurity researchers and consultants, causing an estimated $38 billion in losses. (We don’t have the most up-to-date information on its state as of 2022.)

What Is a Virus?

A virus is a piece of code that can attach to other programs and replicate itself. Viruses usually spread by attaching themselves to emails or files. A worm is different because it seeks out computers instead of attaching itself to other programs. Worms don’t need to attach themselves to anything to travel. They are self-reliant migrators.

A virus remains dormant in your system until you run it or perform other actions, such as enabling macros in an infected DOC file. Once activated, the virus copies itself, corrupts your files, degrades device performance, and spreads to other devices by inserting its code into other programs on your device.

How Do Viruses Work?

In more technical words, a computer virus is a malicious code or program that is developed to change the way a computer works and is designed to spread from one computer to another. But how do they work? A virus inserts or attaches itself to a legitimate program or document that supports macros to execute its code. Once a virus has successfully attached itself to software, file, or document, it will remain dormant until the computer or device is forced to run its code. For a virus to infect your computer, you must first run the infected program, which then executes the virus code.

A virus can have unexpected or harmful outcomes during this procedure, such as hurting system software by corrupting or destroying data. For example, let’s say you try to open a word processing program to create a letter, but it crashes and becomes infected with a virus before you can do so. Now all your word processing programs are infected, and you need to get rid of it if you want your computer back in working order (you do!). While some viruses are intended to be amusing, others can have far-reaching and destructive consequences. This can include wiping data or permanently damaging your hard drive. Worse still, some infections are created with monetary benefits in mind.

Types of Viruses

Computer viruses can be classified based on several factors, including how they spread and whether or not they self-replicate. Some of these classifications include:

  • Boot sector virus
  • Web scripting virus
  • Browser hijacker
  • File infector virus
  • Multipartite virus
  • Macro virus
  • Polymorphic virus
  • Direct action virus
  • Resident virus

What Is a Worm?

A worm is a bundle of destructive programs left on a computer and runs automatically when the computer starts up. Worms can take over a computer, causing it to be inoperable and potentially leading to financial harm. A worm sends copies of itself to other computers on the internet or within its reach. Worn programs cannot be removed simply by rebooting the computer and removing it from the boot list.

A worm is far more dangerous than a virus because of its ability to propagate over the internet without any assistance whatsoever and transmit software packages as it moves along its path; hence, the term ‘worm.’ It spreads like a computer virus but faster and has way more destructive capabilities. The most famous example of a worm was ILOVEYOU which wreaked havoc in 2000 by infecting millions of systems around the world within hours of its release.

How Do Worms Work?

Computer worms are programs that can be disguised as files of any type (such as .exe, .doc, or .xls) and have been designed to automatically spread from computer to computer via a network connection or Bluetooth connection. They operate by taking advantage of vulnerabilities in other programs running on your computer, spreading even when you’re not actively doing anything on your machine and with no intervention from you.

They do so by exploiting security holes in applications like Adobe Reader, Microsoft Office, and Internet Explorer. In fact, it was a vulnerability found in Adobe Reader that led to one of the most infamous worms ever—the W32/Sobig worm—which infected more than one million computers worldwide within hours after its release in August 2003. Worms may also take advantage of weaknesses inherent to operating systems themselves; for example, some older versions of Windows were susceptible to an attack known as Ping of Death which could crash computers remotely if exploited correctly.

Types of Computer Worms

There are several types of computer worms, but each type essentially functions in a similar way—some even rely on many of the same vulnerabilities to spread and infect computers. For example, one type may take advantage of an old vulnerability that hasn’t been patched yet. Another might exploit an unpatched browser vulnerability or use social engineering tactics to trick users into clicking malicious links or opening infected attachments. The main difference between different types of worms is how they operate and what kind of damage they can cause once they’re inside your network. Here are some common types:

  • Email worms
  • File-sharing worms
  • Cryprtoworms
  • Instant messaging worms
  • Internet worms

Virus vs Worms: How Do They Spread?

Computer viruses and worms are spread by different mechanisms. A computer virus requires an initial carrier or vector, such as a floppy disk or email attachment, to transfer itself from one computer to another. With that said, a virus can replicate itself and spread copies of itself around the world. A worm doesn’t need a carrier to spread from one computer to another. Instead of replicating itself, it uses networking tools like security exploits and backdoors to burrow its way from one computer to another.

A worm spreads by copying itself onto removable media such as floppy disks and flash drives that are then shared with others via email or instant messaging programs such as MSN Messenger. Most worms also have self-replication capabilities built into their code. When someone accesses an infected file (such as a document), it automatically copies itself onto their system without their knowledge. Here are some of the ways how devices contact viruses and worms:

  • Email: It is the most common way for malware to spread since it might contain infected attachments and malicious links that contain viruses or worms.
  • P2P file-sharing: If you download music, movies, or programs from unknown sources, you may end up with more than you bargained for.
  • Security vulnerabilities: Developers may inadvertently leave security flaws in their code, which hackers can use to infect your system with malware. A worm can scan a network for vulnerable devices and then exploit them to obtain access.
  • Malvertising: Infected adverts in banners or pop-ups can be found on any website, including genuine ones. You may unintentionally download a virus or worm if you click on them. Some of these adverts can infect you through a drive-by download even if you don’t click.

It’s critical to use caution when surfing the web, downloading data, and opening links or attachments to avoid contact with a virus. To keep safe, avoid downloading random text or email attachments and files from websites you don’t trust.

Virus vs Worm: Summary

Many of us believe that worms and viruses are the same things. This is not true; although these two terms are often used interchangeably, they are different. These terms may be used synonymously with each other, but these terms have their meanings and differences from each other. Both can damage a computer, but they differ in many aspects, as described earlier.

The main difference between worms and viruses is that worms are independent programs while viruses depend on other programs to spread themselves. In addition, worms do not replicate by infecting other files as viruses do. Instead, worms travel through networks or removable media like floppy disks or USB drives. Another major difference between worms and viruses is that worms spread automatically without user intervention, whereas viruses need some action from users before spreading themselves over computers.

Virus vs Worm: Full Comparison FAQs (Frequently Asked Questions) 

How are viruses and worms spread?

Computer viruses and worms spread by taking advantage of flaws in programs, files, or networks. Computer viruses are often downloaded onto a computer when you click on an infected email attachment or receive an infected file via email.

Do viruses and worms need human activation?

Computer worms are programs or codes that spread through networks by themselves—no human interaction required. Computer viruses need humans to activate them—to open an email attachment or click on a link—but once activated, they replicate on their own

What damage can viruses and worms cause?

Identity theft and data loss: Viruses and worms can steal your personal information, resulting in identity theft and financial damage.

Corporate financial loss; brand damage: Viruses and worms can infect businesses, resulting in data theft, repair costs, and tarnished reputations.

Do both viruses and worms travel from computer to computer?

While there are many ways for malicious software to spread from one computer to another, it’s crucial to understand how different types of malicious software behave. In most cases, a worm will not travel from computer to computer—instead, it will replicate itself within a single device (whether a home computer or a laptop). On the other hand, Viruses spread from computer to computer relatively fast.

How do viruses and worms replicate?

P2P file sharing, infected websites, and email attachment downloads are all common ways for them to propagate. When a virus infects your system, it remains dormant until the infected host file or application is activated. At this point, the virus becomes active and can operate and proliferate on your system.

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