Common Types of Computer Virus and How to Avoid Them

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Ever found yourself puzzled by the terms “malware” and “computer virus,” wondering if they’re one and the same?

Don’t get confused.

While these terms are frequently used interchangeably, it’s crucial to differentiate between them. “Malware” serves as the umbrella term encompassing various forms of malicious software—a digital troublemaker, if you will. On the other hand, a “computer virus” is a specific subtype of malware. comparable to a mischievous infiltrator in the vast realm of digital landscapes.

From boot sector viruses to multipartite threats, a variety of viruses infiltrate computer networks, making it crucial to comprehend the inner workings of these digital adversaries when navigating the intricate realm of cybersecurity. In this complex landscape, where every click and download bears potential risks, understanding the nuances of diverse computer viruses becomes imperative. Join us as we delve into a voyage through the extensive taxonomy of computer viruses, deciphering their intricacies and equipping you with the knowledge to strengthen your digital defences.

What is a Computer Virus?

A computer virus is a type of malware or malicious computer program that is designed to infect a computer system and spread to other computers. Like a biological virus, a computer virus can replicate itself and attach its code to legitimate programs or documents, allowing it to spread and execute when the infected program or document is opened or run.

These digital troublemakers aren’t just there to be annoying; they have a mission. They might mess with your files, swipe your sensitive information, or worse, spread their virus vibes to other computers. It’s like the worst game of tag ever, but instead of tagging, they’re infecting.

As per the Australian Institute of Criminology, 2023 survey of 13,887 computer users, a whopping 22 per cent fell victim to various malware, including viruses, trojan horses, ransomware, and more, in the year leading up to the survey, that’s nearly a quarter of the digital population getting hit by these cyber troublemakers. It’s no wonder protecting our computers from these virtual vandals has become more crucial than ever.

So, how do the viruses spread?

Well, they’re not picky. Viruses pull off their infamous party-crashing stunts through:

  • Infected Email Attachments
  • Malicious Websites
  • Compromised Software
  • Removable Media
  • Network Vulnerabilities
  • Social Engineering
  • File Sharing

What are the different types of Computer Viruses?

types of computer viruses

File-Infecting Virus

File-infecting viruses are a type of malware that specifically targets executable files, such as those with .exe or .com extensions. These viruses have the ability to embed their malicious code within these files, effectively infecting them. When an infected file is executed, the virus activates and spreads its payload, potentially causing harm to the system or facilitating unauthorised access.

The Jerusalem virus, also known as the Friday the 13th virus, is an example of a virus discovered in 1987. It primarily corrupted executable files with .com and .exe extensions. The virus was named after the city of Jerusalem because it was programmed to activate and spread every Friday the 13th. Once executed, the Jerusalem virus would infect other executable files on the system, causing them to grow in size with each infection. This growth could eventually lead to system instability and decreased performance.

Also Read: How Can You Avoid Downloading Malicious Codes?

Boot Sector Virus

Boot sector viruses are a type of malware that infect the boot sector of storage devices, such as hard drives or floppy disks. The boot sector is a crucial part of the storage device that contains instructions for the system’s boot process. By infiltrating this sector, these viruses can gain control during the system startup, allowing them to execute their malicious code and potentially compromise the entire system.

An example of a boot sector virus is the Michelangelo Virus, which emerged in 1991. This virus was named after the famous Italian artist Michelangelo because it activated on his birthday, March 6th. The Michelangelo virus infected the boot sector of hard drives, remaining dormant until the designated activation date. Once activated, it overwrote specific sectors of the hard drive, rendering the system unbootable and potentially causing data loss.

Macro Virus

Macro viruses are a type of malicious software that infects the macro programming language in applications like Microsoft Word and Excel. Macros are sequences of commands that automate tasks within these applications. Macro viruses attach themselves to documents and spreadsheets, embedding malicious macros that execute when the file is opened. This type of virus has the capability of infecting multiple documents and spreading rapidly through shared files, exemplifying its proficiency in modifying other computer programs.

Emerged in 1999, the Melissa virus, one notable example of a macro virus, was spread via email and primarily targeted Microsoft Word documents. The Melissa virus arrived in the form of an email with an enticing subject line and an infected Word document attached. The Melissa virus infected Word files through email attachments. It replicated itself and sent infected documents to the first 50 contacts in the user’s Outlook address book, causing widespread disruption.

Polymorphic Virus

Polymorphic viruses are a type of malicious software that can change their code or appearance each time they infiltrate a new file or system. This ability to mutate makes it challenging for traditional antivirus programs to detect using static signature-based methods. Polymorphic viruses aim to evade detection by altering their characteristics while maintaining the same malicious functionality.

The Storm Worm, active around 2007, is an example of a polymorphic virus. It spreads through malicious email attachments or links, often disguised as greeting cards or news alerts. The virus had the capability to change its code and appearance continually, making it difficult for antivirus software to identify and block its variants effectively. The Storm Worm was not only polymorphic but also part of a botnet, a network of infected computers controlled by a central server.

Metamorphic Virus

A metamorphic virus is a sophisticated type of malicious software that can entirely rewrite its own code while maintaining its original functionality. Unlike polymorphic viruses that alter their appearance while keeping the underlying code similar, metamorphic viruses undergo complete transformations, making them even more challenging to detect and analyse. The constant code changes make it difficult for traditional signature-based antivirus solutions to recognise the virus consistently.

The “Win32/Simile” virus is a well-known example of a metamorphic virus. It was discovered in the early 2000s and targeted Windows systems. The Win32/Simile virus was designed to infect executable files and spread across a network. When infiltrating a file, the Win32/Simile virus completely rewrites its code, changing its structure, instructions, and overall appearance. It would rearrange the order of instructions, modify register usage, and substitute certain code sequences with equivalent but differently structured instructions.

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Resident Virus

A resident virus is a type of malware that embeds itself into the computer’s memory (RAM), allowing it to stay active and execute malicious actions as long as the corrupted system is running. Unlike non-resident viruses that need a host file to be executed, memory-resident viruses load into memory during the system’s startup, enabling them to operate independently. These types of viruses often employ stealth techniques to avoid detection, such as intercepting system calls and modifying the results to hide their presence.

The CMJ virus demonstrates a trait of resident viruses by residing in the memory and executing its code discreetly. Discovered in the late 1980s, It primarily targeted MS-DOS systems. Once a system was infected, the CMJ virus embedded itself in the computer’s memory and could invade other executable files as they were accessed or executed.

Multipartite Virus

A multipartite virus is a unique type of virus that infects computer files by combining features from both file-infecting viruses and boot-sector viruses. This fusion allows the virus to target various file types along with the boot sector of a computer’s storage device. This dual capability makes them more complex and potentially more damaging than viruses that target only one of these components.

The Tequila virus is an example of a multipartite virus that was discovered in 1991. It primarily targeted MS-DOS systems. The Tequila virus infected both executable files and the boot sector of the hard drive, exhibiting characteristics of both file-infecting and boot-sector viruses. When an infected program was executed, the virus would load into memory and infiltrate other executable files. Tequila viruses can be particularly challenging to detect and remove because they invade multiple components of a system.

Direct Action Virus

One kind of computer virus known for its uncomplicated and direct mode of operation is the direct action virus. A direct-action virus acts instantly upon the execution of an infected file, in contrast to certain other virus kinds that might conceal themselves or go dormant for some time. Usually, it targets particular files or programs and launches its payload as soon as the compromised file is opened. The fact that these viruses typically don’t try to conceal or remain resident in the system’s memory is one of their distinguishing characteristics. Rather, they concentrate on corrupting files and producing noticeable, instantaneous impacts.

The Vienna virus is an example of a direct-action virus that appeared in the 1980s. It targeted executable files, and when a corrupted file was executed, the virus took direct action by infiltrating other executable files in the same directory. The Vienna virus did not attempt to hide its presence and immediately manifested its effects upon execution.

Overwrite Virus

Overwrite viruses are a type of malicious software that, as the name suggests, overwrites content in files or on storage media with malicious code. This virus modifies or replaces existing files or data with its own malicious code. When an overwrite virus infects a file, it completely overwrites the original content, rendering it unusable or destroying it, causing data loss, corruption, or corruption of critical system functions, depending on the files they target and the extent of their damage.

The “Way” virus is an example of an overwrite virus which primarily targets executable files. When an executable infected by the Way virus was executed, the virus would overwrite a portion of the file’s code with its own malicious code. It did not create new files but instead modified existing executable files.

Browser Hijacker

A browser hijacker is a type of malicious software that alters the settings of a web browser without the user’s consent or knowledge. It modifies the browser’s homepage, default search engine, and new tab page, redirecting the user to unwanted websites or search results. Browser hijackers often aim to generate advertising revenue or collect user browsing data for malicious purposes.

Conduit Search is an example of a browser hijacker that gained attention in the past. If a user unintentionally installs software linked to Conduit, it can manipulate browser settings on computers or mobile devices, such as modifying the default search engine and homepage. Consequently, instead of using the user’s preferred search engine, Conduit Search redirects searches through its own engine, potentially displaying manipulated search results infused with sponsored.

Web Scripting Virus

A Web Scripting Virus adeptly exploits browser vulnerabilities, breaching security through client code scripts. This virus disguises itself as webpage ads and pop-ups, this insidious threat swiftly compromises device security, altering the registry, modifying browser pages, and stealthily stealing confidential data. Predominantly targeting popular social networking sites, this malicious virus spreads rapidly, causing performance issues, sending spam mail, victimising users, and risking data damage.

This virus empowers some dangerous attacks like DDoS attacks. There are two types of web scripting viruses: persistent and non-persistent. In a persistent virus attack, the attacker directly targets the browser’s cookies, seizing control of the user’s session. On the other hand, a non-persistent virus attack takes place without the user’s awareness, with all malicious activities unfolding in the background.

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Spacefiller Virus

A spacefiller virus, also referred to as a cavity virus or sparse infector, is a form of self-replicating computer virus that infiltrates files by embedding its malicious code into unutilised or vacant areas within the compromised file. In contrast to typical viruses that modify existing code, a rare type of virus, cavity virus leverages the empty spaces within a file to hide its code and replicate. The primary objective is to enhance the likelihood of remaining undetected by antivirus software and other security measures.

An example of such a virus is CIH, also known as Chernobyl, which emerged in 1998. CIH gained notoriety for its capability to incapacitate computers by overwriting crucial system files and, in severe instances, damaging the BIOS, rendering it challenging or impossible to boot the system.

How to Avoid Computer Virus Infection?

Protecting your computer from viruses and boosting your cybersecurity should be a top priority for everyone in this digital era. To ensure your system’s safety, strict adherence to these crucial measures is imperative:

  1. Employ Reliable Antivirus Software: Set up and maintain up-to-date trustworthy antivirus software. Make sure the software’s virus definitions are current and run regular virus scans on your computer.
  2. Constantly Update Your Software and Operating System: Turn on automatic updates for your web browser, operating system, and other programs. Security patches, which address weaknesses that viruses exploit, are frequently included in updates.
  3. Use Caution When Opening Email Attachments: When opening email attachments, use caution, particularly if the sender is unknown or the email looks dubious as it may include malware that could access your machine. Only open attachments if you are certain of their authenticity. Examine attachments with an antivirus program before you open them.
  4. Download files with caution. Download files from reliable sources only, including official websites or reliable download sites. Downloading files from peer-to-peer networks or untrusted sources should be done with caution as they can contain malware.
  5. Avoid Clicking on Dubious Links: Exercise caution when you click on links in social media, instant chat, or email correspondence. Before clicking, move your mouse over the link to view the full URL. Don’t click on anything that appears strange or unexpected.
  6. Make Regular Backups of Your Data: Make sure you frequently restore your critical files and data. With data backup and recovery solution, store your backups securely offsite, either on cloud storage platforms or alternative devices. Having these backups readily available allows for file restoration in the event of a virus infection or data loss.
  7. Employ Robust and Distinctive Passwords: Craft robust and distinct passwords for your virtual accounts. Employ a mix of numerals, symbols, and capital and lowercase letters. Steer clear of using the same password for several accounts or using one that is widely used. To safely generate and store passwords, think about utilising a password manager.
  8. Enable Two-Factor Authentication (2FA): Whenever your online accounts allow it, turn on 2FA. By requiring a second verification step in addition to your password—for example, a unique code texted to your mobile device—this increases security.
  9. Be Wary of Social Engineering Techniques: Cybercriminals employ social engineering techniques to trick and manipulate people into disclosing personal information. Avert answering opportunistic calls, emails, or messages that want private or financial information.
  10. Alert Yourself: Keep up with the most recent cybersecurity dangers with vulnerability scanner and recommended procedures. Enrol in advanced cyber security training to identify the common strategies employed by phishing scammers and hackers.

In a world where each passing day sees the relentless evolution of malware threats, the need for a robust defence against viruses and malware takes centre stage. Whether confronting the stealth of file-infecting viruses or grappling with the dynamic nature of polymorphic and metamorphic viruses, staying ahead of the curve is not just a necessity but a strategic imperative. 


At Binary IT, our commitment goes beyond mere protection; we offer proactive solutions, including dark web scans and extensive cyber training, empowering you to build an unassailable digital fortress. Don’t wait until a virus breaches your systems—seize control now. Reach out to us, where advance solutions meet unparalleled expertise, and let’s turn the challenges of cybersecurity into a catalyst for a safer and more resilient digital future.

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