What is a Computer Virus? | Types of Computer Virus & Definition

What is a Computer Virus? | Types of Computer Virus & Definition 

A computer virus is an illegal, harmful, or malicious program that can change the way your computer runs and behaves. A computer virus is a sort of malware that attaches itself to another program and can replicate and propagate once it has been installed on a user’s computer. When a computer changes the way in which it should work normally, it is said to be infected by a virus. This virus may spread from one computer to another if you receive an email with a harmful attachment, when open the file, and the computer virus then infects your machine. Or in other words, a harmful software application that is installed without the user’s consent on their computer and then performs some malicious acts is known as a virus. Computer viruses are harmful but the majority of them engage in malicious activity, such as data destruction.

 

History of Computer Virus

 first computer virus

The “Creeper system” is the first computer virus, was an experimental self-Multiplying virus launched in 1971. Then, the Rabbit virus came in the mid-1970s and was extremely active and it self-replicated very fast & wrecked the functionality at the same speed. The first PC virus was known as “Elk Cloner” and was built in 1982, by Rich Skrenta. It spread by a floppy disc with a game on it and hooked itself to the Apple II operating system.
“Brain,” the first computer virus for MS-DOS, was introduced in 1986. The boot sector of the floppy disc would be overwritten, preventing the computer from booting. It was created by two Pakistani brothers and was intended to be used as a copy protection system. In 1988, the age of catastrophic viruses began. Most viruses were basically joked with humorous names and messages till then. In 1988, “The Morris” was the first virus that propagated widely.

 

What Is a Computer Virus and How Does It Work? 
How a computer gets a virus?

Ø  Opening suspicious email attachments

Ø  Attaching unsecured removable or external storage devices (e.g., flash drives, external hard drives, memory cards)

Ø  Accessing malicious websites

Ø  Clicking malicious ads

Ø  Downloading malicious and unlicensed applications

Ø  Sharing the data like music, files, and images with each other.

Ø  If you open a spam email or an attachment in an email that is sent by an unknown person.

Ø  Downloading the free games, toolbars, media players, etc.

Ø  Visiting a malicious website.

Types of computer virus

Boot sector virus

 This virus infects the boot sector of the computer and runs every time the computer boots and before the operating system loads. Floppy discs and other bootable media become infected. They are sometimes referred to as memory viruses because they do not infect the file system.

File Virus

 Infects the system by appending itself to the end of a file. It changes the start of a program such that the control jumps to its code.

 

Email-Virus

They are comprised of malicious code that is propagated through email messages and can be activated when a user clicks on a link in an email message, opens an email attachment, or interacts in any manner with the infected email message.

 

Polymorphic Virus

 Poly means many and morphic means forms. So this virus changes its form every time. A virus signature is a pattern that can be used to assess whether a virus exists or not (a series of bytes that make up virus code). This virus changes itself every time when it is installed so that it can avoid detection by antivirus software. Here, only the signature of this virus is updated, the functionality remains the same. 

 

Macro Virus

 These viruses are activated when a program capable of performing a macro is executed. Macro viruses, for example, can be found in spreadsheet files.

 

Multipartite Virus

 This virus has the power to infect a computer’s boot sector, memory, and files, among other areas. This complicates its detection and containment.

 

Encrypted Virus

 To avoid detection by antivirus software, this type of virus is encrypted. There’s also a decryption algorithm included. As a result, before running, the virus decrypts.

 

Stealth Virus

This virus is difficult to detect because it modifies the code used to detect it. As a result, virus detection is extremely difficult.

 

Resident Virus

 A virus that saves itself in the computer’s memory before infecting additional files and programs after the original software stops working. Because it is hidden in the computer memory and difficult to remove, this virus can easily infect other files.

 

Direct action Virus

If a virus is tied to an executable file and when the file is opened or run, that virus gets installed/ spread, it is known as “direct action”. This virus does not delete any files or lay impact on the speed of the system; it just renders your files inaccessible.

 

Trojan horse

This notorious program is also simply called a Trojan.  These viruses appear to have a benevolent or helpful function. However, they can inflict damage once it gains access to the system—like the infamous wooden horse from the Trojan War.

Web scripting virus

This is a very harmful kind of virus hidden in the coding of links, videos, advertisements, or code within a malicious website. If the user accesses an infected malicious website, the virus will enter the system and cause harm by breaching the web browser security.

File infector .exe

This kind of file can infect the computer when the file is launched. However, this virus can only run after the file is launched. Most file infector viruses only replicate and spread, taking up storage, but others damage host programs and licensed applications.

Computer worms

Computer worms can come from software vulnerabilities, malicious email attachments, or instant messages from social networking sites. These pernicious programs can replicate and infect entire networks of computers without the user’s permission or any human interaction. After replication, they can steal information, corrupt sensitive files, or change the computer system’s settings.

Malware

Malware is a generic computer term that refers to some kind of program that is malicious. As an umbrella term, computer viruses are then also considered malware. Common kinds of malware include spyware, adware, trojan horses, and computer worms. They can steal information, damage hardware and software technologies, or monitor users.

 

Spyware, one of the most dangerous types of malware, can observe user activities online or offline. It can monitor private activities, such as web browsing and online shopping. Hackers executing spyware may have the means to view your passwords, bank account information.

 

What does a computer virus do?

A virus can harm or destroy data from system, slow down system resources, and log keystrokes, among other things. A virus has the ability to have unexpected or harmful outcomes during this procedure, such as destroying system software by corrupting data. Some computer viruses are designed to damage your computer by destroying files, corrupting applications, or reformatting the hard drive. Even less dangerous computer infections can have a substantial impact on your system’s performance, eating up RAM and triggering frequent crashes. Other viruses may just clone themselves or flood a network with traffic, rendering all internet activity difficult. 

 

Indications of a computer virus?

Ø  Slowing down of system without any reason.

Ø  The homepage is replaced by a website and you would not be able to undo that replacement.

Ø  Identifying that your files are corrupted.

Ø  Change in the name of your hard drive & also change in its volume.

Ø  Change in amount of free memory available.

Ø  Not able to find your files or programs.

Ø  Unknown change in the password that does not let you login.

Ø  A virus may damage your hard drive and our device may freeze or crash as a result of this.

How to remove computer viruses?

The simpler approach is to install antivirus. Antivirus software is a program that searches for, detects, prevents, and removes software infections that can harm your computer. Antivirus can also detect and remove other dangerous software such as worms, adware, and other dangers. This software is intended to be used as a preventative measure against cyber dangers, keeping them from entering your computer and causing problems. Antivirus is available for free as well. Anti-virus software that is available for free only provides limited virus protection, whereas premium anti-virus software offers more effective security. For example Avast, Kaspersky, etc.

 

Best Tips for prevent Computer Viruses

 

Update your system regularly

Make sure to update your operating system, browser, and installed programs. Updates will often include additional safety features designed to protect your computer against the latest threats. Viruses can usually find an entry point from an out-of-date browser, operating system, or software application. Regularly check for software updates as much as you can or allow your device to automatically update software programs and systems.

Remain alert

Always assume the worst when it comes to links and attachments from unknown sources. Hackers and malware authors can use clickbait to lure unsuspecting internet users into clicking on a suspicious link. This action will download the virus onto the user's system.

Check the URL

The universal resource locator, or URL, is the web address at the top of each webpage. If you click on a suspicious link, this might present a suspicious URL. Legitimate URLs begin with “https” instead of just “http” as proof that they are encrypted and can protect sensitive information. When you access a website, always check the URL and the website privacy protocols.

Install and use security features

Many antivirus and anti-malware programs are designed to protect your computer from threats. However, it’s also important to get the right kind of protection for your system. Only trust software products with an established reputation, and always download applications directly from the main website of the company, brand, or product. If you don’t want to look too far, you might want to view the features offered by McAfee’s family of security products.

Update your antivirus software

An antivirus software always knows what a computer virus is, so ensure that it’s always up-to-date. Updated versions improve the security features by patching any vulnerable security areas of your device and software programs. They can also handle the latest cyber threats and malware programs.

 

 

Question 1. How can you protect your computer system from viruses?

Ans:

We can use antivirus software to keep your computer safe from viruses. Antivirus software works by comparing the files and programs on your computer to a database of known malware types. It will also monitor computers for the presence of new or undiscovered malware threats, as hackers are constantly generating and propagating new viruses. 

 

Question 2. Make a list of frequent computer virus infection sources. 

Ans:

1. Downloading programs/software from the internet.
2. Emails
3. External devices like pen-drives.

4. Using an unknown CD to Boot data
5. Bluetooth/ infrared

 

Question 3. Why is it a good idea to back up data on a regular basis?

Ans:

Files that have been damaged can be restored by backup.

 

Question 4. How do computer viruses spread?

Ans:

Computer viruses are typically propagated by email, file sharing, or CDs or by downloading file(s) from unauthenticated sources. 

Question 5. What is a computer virus?

Ans:

It is a harmful software application that is installed without the user’s knowledge/ consent on their computer and then performs some malicious acts, is known as a virus. It attaches itself to another software, once infected the system, in such a way that the host program’s execution activates the virus’s actions simultaneously.