What is Computer Virus?
If you use the internet then you must have heard names like Virus, Malware, Trojan. All these are types of viruses that harm our computers.
In today's article, we are going to know in detail what is computer virus? And how do they harm our computers? And how many types of computer viruses are there?
So without wasting any time, let us first know what a is Computer Virus?
What is a computer virus?
Computer Virus is an unwanted software program or in other words, it contains some codes and instructions which interfere with the functioning of our computer.
Viruses enter our computers through insecure internet, files, etc. and as soon as they enter our computers, their numbers start increasing and then from one file to another, from another file to another program, and then from one computer to another. Spread to other computers.
Due to this tendency of a virus, it is also called self-replicating computer programs which hinders the functioning of computers by infecting files and programs. Sometimes computers become slow and crash due to viruses.
Just as biological viruses like coronavirus, flu, etc. spread through people shaking hands, hugging, and touching each other, similarly computer viruses also spread from one computer to another.
When we connect two computers, the viruses present in one computer enter the other computer and infect it too.
There are many types of anti-virus software available in the market which scan our computer and destroy any virus if found.
Some famous Antivirus Software are as follows: Avast, Quick heal, McAfee, Kaspersky, Norton, AVG Technologies, etc.
Definition of Computer Virus
Definition of Computer virus: A computer Virus is a program that enters the user's computer without his permission and performs malicious activities (such as changing the code of a program, deleting a file, etc.).
The word virus comes from Latin and means “ poison ” or “ slime ”.
The term 'computer virus' was first formally defined by Fred Cohen in 1983.
In today's digital world, there are many types of viruses that are created to harm the computer in different ways. Let us know about those types of computer viruses.
Types of Computer Virus
In today's technological world, various types of computer viruses exist and new types of viruses are coming day by day. Some of the main types of computer viruses are as follows :
- Computer Worm
- Overwrite Virus
- Resident Virus
- Trojan Horse
- Macro Virus
- Boot Virus
- Cavity Virus
- CMOS Virus
- Rabbit Virus
- Encrypted Virus
1) Computer Worm
Computer Worm is also like a virus which multiplies itself and spreads throughout the computer. As soon as the computer worm enters the computer, it starts making copies of the files present in the computer, due to which the computer storage becomes full and the computer becomes slow.
It does not require a host like a virus. Computer Worm spreads through the network, such as when you receive an email from a Virus Infected email ID, it is possible that your computer also gets infected with a Computer Worm.
2) Overwrite Virus
This is the simplest and quite dangerous computer virus which overwrites the file code of the host computer with its malicious code. Due to its tendency, it is called Overwrites computer virus.
Overwrite Virus completely replaces the host's program code with its malicious code without changing its size.
Overwrite Virus is mainly made to destroy data and program applications. It is a bit difficult to identify because it spreads through email.
3) Resident Virus
The Resident Virus is permanently stored in the computer's RAM, which becomes active as soon as the computer starts and corrupts the files and programs running in the computer.
This virus can easily infect other files. Resident Virus is difficult to identify and remove from the computer system because it is hidden in the memory.
Non-resident Virus
It does not remain in the memory like a residential virus, hence it is not executed from the computer's memory, it has to be executed.
4) Trojan Horse
A Trojan horse is a malware like virus or worm, which is technically different from both. It cannot replicate itself like viruses and worms.
Trojan horse is hidden in the program. Which enters your computer when you install any program in your computer that contains a Trojan horse virus.
It accesses your computer unauthorizedly and can delete any file on your computer, send the file to anyone, and do any unwanted activities.
5. Macro Virus
Macro viruses add their code to macros attached to documents, spreadsheets, and other data files. The concept was the first macro virus, which appeared in July 1995.
It also spreads through software programs, which execute macros like Microsoft Word, and Microsoft Excel. Whenever these documents are opened, they infect other documents as well.
The concept was the first macro virus that spread through email by attaching itself to Microsoft Word and infected Microsoft Word 6.0 and Microsoft Word 95. Well, the good thing is that this virus did not do any harm except printing some messages on the screen.
Types of macro viruses
Macro viruses can be found in many different forms.
- Concept Virus
- Melissa Virus
1) Concept Virus
Concept Virus was the first macro virus, which appeared in July 1995 and targeted Microsoft Word.
2) Melissa Virus
Melissa Virus is the first macro virus with email worm characteristics which started spreading through email on March 26, 1999.
6) Boot Virus
Boot virus, which we also know as Boot sector virus, changes the boot sector program which is stored in the hard disk or any other floppy disks. It replaces the boot sector program with its malicious version.
Boot virus infects the computer only when it is used to boot the computer. If it enters after the boot-up process, it does not infect the computer.
For example, if someone forgets to remove the infected floppy disk when the PC is turned off and then turns on this PC, the infected boot sector program runs during the booting process.
Boot viruses usually enter computers through corrupted media files, infected storage devices, and insecure computer networks.
However, due to the decline in the use of floppy disks and the use of boot-sector safeguards in operating systems at present, the spread of this virus has reduced significantly.
7) Cavity virus
It is also known as the spacefiller virus. Its name itself defines its function. As the name suggests, spacefiller means that it occupies the empty parts of the file. It installs itself on empty parts of the file.
This virus is not easy to detect because it fills empty spaces without changing the file size. Due to this, the performance of the computer goes down considerably.
8) CMOS Virus
This is a dangerous virus that infects CMOS (Complementary Metal-oxide Semiconductor). It is a memory chip that contains the system configuration. This virus can erase or reset the system configuration. Which can be very harmful to your computer.
9) Rabbit Virus
This is a dangerous virus which is also known as a wabbit, fork bomb. This virus can create new processes which further create new processes. This virus does this until it completely utilizes all the resources of the computer system. Due to this, the resources in the computer are reduced and the computer becomes slow.
This virus works to slow down and crash the computer system because it uses all the resources itself.
10) Encrypted Virus
Encrypted Virus encrypts its payload to make its detection more difficult. It consists of two parts: an encrypted virus body and a decryptor, which when executed decrypts the virus. After decryption, the virus starts making copies of itself and executes itself.
This is different from CryptoLocker (which is a computer virus that encrypts hard drive data and holds it for ransom),
Ransomware and Crypren are examples of encrypted viruses that encrypt the victim's files. An encrypted virus uses an encryption method to hide itself making it difficult to be detected by scanning with a malware scanner (such as an antivirus).
When a computer is infected with this virus, encrypted viruses can make changes to existing registry entries and can also destroy system processes that interfere with their encryption.
Symptoms of a Computer Virus
There are many warnings and symptoms which tell whether our computer is infected with a virus or not.
Let us know about some such signs or symptoms.
- Slow computer performance
- Frequent pop-ups
- Hard Drive issue
- Frequent crashes
- Unknown programs
- Unusual activities
- Impaired security solutions
- Network issue
- Unnecessary advertisement
- Display problems
- Affected Applications
- Blocked by Antivirus Sites
- Dialog Boxes
- Changed Homepage
- Log out from Accounts
- Crashing of the Device
- Mass emails being sent from your email account
1) Slow computer performance
If your computer is infected with a virus, then your computer will become very slow, such as it will take a lot of time to open and shut down the computer, and it will take more time for any file, document or application to open than before, etc. Could Apart from this, your operating system and internet may also become slow if your computer gets infected.
2) Frequent pop-ups
You may see unusually frequent pop-ups on your computer. Which is a sign that your computer has been infected with a virus.
3) Hard Drive issue
A hard drive located in a computer may exhibit abnormally high activity when it is infected with a virus, even when it is not in use. Viruses can cause unwanted changes to your hard drive and may even cause the device to freeze or crash.
4) Frequent crashes
If your system suddenly crashes while playing games, watching videos, or doing some other work while using the system and a blue screen appears after the crash, then it is a symptom of a virus.
5) Unknown programs
Opening of unwanted programs when the computer is opened, sometimes the computer shuts down unexpectedly, etc. are symptoms of virus in the computer.
6) Unusual activities
If your machine performs differently than before, such as not being able to log into your account, not being able to delete corrupted files and many more, these are signs of a virus.
7) Impaired security solutions
If your computer has been infected with a virus, sometimes your antivirus may not work properly.
8) Network issue
Sometimes, if your computer is infected with a virus, you may experience high network activity even when you are not connected to the Internet.
9) Unnecessary advertisement
Although we often see advertisements when we browse, but if you see them even when you are not browsing, then it is a sign of a virus in your computer.
10) Display problems
If you are experiencing different colors on your computer screen, it could be a symptom of a computer virus.
11) Affected Applications
If some programs in your computer are not working properly, it may be that your computer is infected with a virus. Many viruses are created to affect only some specific applications.
12) Blocked by Antivirus Sites
If the computer is infected with a virus, the antivirus site may deny the assessment of the computer.
13) Dialog Boxes
If many dialog boxes are suddenly appearing on your computer screen, then it is a sign that your computer is infected with a virus.
14) Changed Homepage
If your computer's home page changes without you knowing, it may also be a sign that your computer has been infected with a virus.
How do viruses enter the computer?
Viruses can enter a computer for many reasons :
- From spam email or email attachment.
- While sharing songs, files, movies, photos, etc. with friends.
- By visiting any infected website.
- Installing software applications without fully reading the license agreements.
- Your computer can get infected with viruses by downloading infected games, toolbars, media players, and other systems for free.
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Conclusion
In today's article, we talked about light pen and learned what is computer virus? And how do they harm our computers? And how many types of computer viruses are there?
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