5 Most Dangerous Computer Viruses & How Computer Viruses Work?

Last updated on June 6th, 2023 at 06:47 am

What is Computer Virus?

        A smart set of computer instructions that can disturb the computer’s working method, this malicious code collection is called a computer virus. It can automatically make multiple copies of itself and can make a computer completely inoperable. Computer viruses are quite similar to biological viruses, they can spread and infect similarly. Computer viruses can perform many operations as they can steal confidential data such as usernames, passwords, security questions, etc., and can damage or encrypt the targeted devices’ data. In short, we can define a computer virus as A type of malicious program that can replicate itself, damage the device, and can infect other computers as well is said to be a computer virus.

How does a Computer Virus Works?

        Usually, most computer viruses are found hidden behind other computer files to evade the security mechanism of a computer. There are many ways the computer virus spreads such as through emails, portable devices like flash drives, SD cards, and many malicious or compromised websites that embed viruses behind the files made available for public access, these often contain pirated versions of paid and expensive application software. Files found with abnormal performance are likely to be infected with a virus. Sometimes virus vendors try to spread the virus through their social engineering techniques, and sometimes they manipulate the system vulnerabilities to let their project meet success. By clicking or executing these infected files many unwanted popups appear, and the operating system becomes slower than usual. Drivers’ software stops working and more worst is that the system fails to reboot.  

How computer Virus makes its multiple copies

        The majority of computer viruses target the Microsoft Windows operating system because Windows OS is the most used operating system on the planet, whereas other Open-Source operating systems are considered more secure than Windows. After all developers all around the globe are contributing to making these open-source operating systems more secure against viruses and other types of hacking.

History of Computer Viruses

        In 1949, American computer scientist and mathematician John von Neumann delivered lectures on  “Theory and Organization of Complicated Automata” which was about, how a computer program can self replicate. His model was considered the first computer virus program and He is called the Father of Computer Virology. Many thesis and articles were published until the 1970s, The first self-replicating program The Creeper was written for experimental purposes and it was spread through ARPANET and infected the PDP-2 devices. Later a program called Reaper was used to remove The Creeper.

        The term Computer Virus was coined for the self-replicating programs in 1984, by Fred Cohen after he published his studies “The Computer Viruses – Theory and Experiments”. His studies further described that all computer viruses can’t be detected perfectly by any algorithm. He described his studies with a theoretical example: Compression Virus that was far away from malicious usage.

        1986 was the year when the first PC virus was created by two brothers Amjad Farooq, and Basit Farooq Alvi from Lahore Pakistan. They created a boot sector virus named The Brain Virus for IBM PCs to prevent piracy issues against their written software. This virus was stored in the floppy drive’s boot sector and avoided the user to copy its data.

        In 1992, the first virus for Windows OS was created named WinVir, in 1996, An Australian originated Boza Virus appeared for the lastly released Windows 95, than-after many computer viruses like Laroux and Staog in 1996, The CIH virus in 1998, ILOVEYOU virus in 2000, Starbucks virus in 2006, and this list never stops. Many tech companies made anti-malware and anti-virus software to tackle these computer viruses.

Types of Computer Viruses

1. Resident Virus: The resident virus is programmed to persistently store and hide inside the computer storage or memory and perform its actions when it is instructed by the writer.

2. Macros Virus: The files with extension .doc, .docx, .xlxs, and other office files contain (not always) this virus and this virus spreads through these office file types.

3.  Boot Sector Virus: A boot sector virus is a strong virus type that can affect the entire operating system and can make a computer unbootable, it can corrupt the operating system as well as the data inside the storage.

4. Browser Hijacker Virus: A Browser Hijacker virus can steal the login details, autofill data, browsing history, cookies and cache, and other useful information by hijacking the browser.

5. Web Scripting Virus: A web scripting virus manipulates an outdated browser’s security flaws and vulnerabilities and redirects the user to the malicious website. The new browsers have many types of security measures to detect and prevent web scripting viruses.

6. Multipartite Virus: This type of virus spread & expands through networks and corrupts the computer’s important files and essential resources. such as operating system, and other basic files responsible for computer operations.

7. File Infector Virus: Such malicious file which hides behind the system files of a computer, and can infect other files as well is called a file infector virus. It can be so annoying for owners of computers to operate a system that is infected by an infector virus.

8. The Polymorphic Virus (Stealth Virus): A polymorphic virus is also known as the stealth virus because this type of virus is designed smartly to evade the antivirus software and bypass the firewalls.

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5 Most Dangerous Computer Viruses

1. ILOVEYOU Virus: In May 2000, many computers across the globe were found infected with the ILOVEYOU virus, also known as a “Love Bug” spread through an email with the subject “Love Letter for You”. The email contained an executable .vbs file named “Love-Letter-For-You.txt” (the .txt extension was used to trick the victim). This virus infected approximately 50 to 55 million computers worldwide and caused damages worth approximately $8 billion as a whole.

2. MyDoom Virus: This computer virus is also known as Novarg, Shimgapi, it used to spread rapidly through emails and was first found on January 24, 2004. MyDoom broke the record of the ILOVEYOU virus and spread over half a billion computers all over the world. MyDoom had great algorithms to evade the antiviruses, it contained various types of payloads and backdoors to infect the computers running the Microsoft Windows Operating system. MyDoom caused damage estimated at $38 billion (inflation excluded).

3. Code Red Virus: In July 2001, Microsoft IIS servers were observed under attack by a virus named Code Red Virus. A buffer overflow vulnerability was manipulated to develop the virus. The code red virus spread instantly and approximately 2 million servers were affected by this Virus, and it is accounted for damage worth $2.6 billion.

4. The Melissa Virus: This virus appeared in March 1999, targeting devices with Microsoft Word and outlook. Melissa virus used the mass mailing services to spread around. All infected devices were found with the same email context “Here’s the document you asked for, don’t tell anyone”. And the attached document was infected with the virus and instructed to send this email copy to the first 50 contacts on the victims’ devices. It infected thousands of computers and caused damage worth $1.2 billion.

5. Conflicker: This is the most destructive virus that destructed about $9 billion and was found in November 2008, and infected around 15 million computers worldwide. It was an advanced computer virus that affected many Police and Military computers as well. Conflicker virus manipulated the Windows security flaws and had many evading techniques. Many militaries and higher authorities across the globe were impacted by this virus. 

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