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Explain what is computer virus, types of virus



what is computer virus

The virus is the most harmful thing in Our Internet or Social Life. In this article, You will know about what a is computer virus, the Evolution of the virus, and different types of computer viruses and malware.

What is a Virus?

The virus is basically a small program. But the difference between the virus and any other program is that a virus manipulates and corrupts information. Once they are lodged, they control the activities of the host. This is possible because each strain of the virus contains within itself, all the information required to make perfect copies of it.

A computer virus is a software code that replicates itself. It spreads from program to program and from disk to disk, manipulating, and damaging valuable data. The major cause for concern is the spreading and damaging nature of viruses.

Most of the viruses are designed to perform simple feats, they do the following:

Corrupt the most sensitive area of the disk File Allocation Table (FAT) of the directory area. Modify the interrupt organization of the system; when a “read or write to screen operation” takes place, it is routed through the virus code in the memory resulting in interrupt clashes where a program opens up a file simultaneously for read-write access.

The virus interrupts every operation of the. Even though the virus may have instructions built into it to destroy data, it can nevertheless render a disk full of files absolutely useless.

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The Evolution of Virus:

The concept of virus dates back tO 1949 when John Von Neumann submitted a paper putting forward the concept of a self-replicating program. Subsequently, the first virus-like program appeared in the form of a recreational game called “CODE-WARS” at the Bell Labs of American Telephone and Telegraph Company.

In “Code-wars,” two players were told to code a set of programs that would destroy the programs of other players. Realizing the potential danger of such programs, the authors did not reveal the presence of such programs. Concurrently, at Massachu- setts Institute of Technology, students were carrying out experiments with the computer, which nobody had ever tried. Their relatively harmless hobby of messing up with other programs gave rise to the idea and concept of computer viruses.

The first commercial application of computer virus was in 1985 when two Pakistani brothers, in order to keep track of software piracy, used the Brain virus also known as the Pakistan virus on their low-cost software sold from their outlet in Lahore.

Classification of type of Computer viruses :

  • File viruses

File viruses, also known as parasitic or executable viruses, are pieces of code that attach themselves to executable files, driver files, and compressed files, and are activated when the host program is run. After activation, the virus may spread itself by attaching itself to other programs in the system. Most file viruses spread by loading themselves in system memory and looking for any other program locked on the drive.

Some Examples of file viruses are Randex, Meve, and MrKlunky.

  • Boot Sector Viruses

A boot sector virus affects the boot sector of the hard disk, which is a very crucial part. The boot sector is where all information about the drive is stored, along with a program that makes it possible for the Operating system to boot up. By inserting its code into the boot sector, a virus guarantees that it loads into memory during every boot sequence. A boot virus does not affect files; inserted, it affects the disks that contain them. Though boot viruses still exist, they are rare compared to new-age malicious software.

Some Examples of Boot Sector viruses are Polyboot, AnitiEXE.

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  • Multipartite Viruses

Multipartite Viruses are a combination of boot sector viruses and file viruses. These viruses come in through infected media and reside in memory. They then move on to the boot sector of the hard drive. From there, the virus infects executable files on the hard drive and spreads across the system. There aren’t too many multipartite viruses in existence today but in their heyday, they accounted for some major problems due to their capacity to combine different infection techniques.

An example of Boot Multipartite viruses is Ywinz.

  • Macro Viruses

Macro viruses infect files that are created using certain applications or programs that contain macros. These include Microsoft Office Documents such as Word, Excel, PowerPoint, Access database, and other similar application files such as Corel Draw, AmiPro, etc. Since macro viruses are written in all languages of the application, and not in that of the OS, they are known to be platform-independent-they can spread between windows, Mac, and any other OS, so long as they’re running the required application. The first macro virus was written for Microsoft word and it was discovered back in August 1995.

Some Examples of Macro viruses are Relax, Melissa. 

  • Network Viruses

This kind of virus is proficient in quickly spreading across a Local Area Network(LAN) or even over the internet. Usually, it propagates through shared resources, such as shared drives and folders. Once a new vulnerable system is found, the network virus infects the other system and thus spreads over the network.

Some Examples of Network viruses are Nimda and SQL Slammer.

  • E-mail Viruses

An e-mail virus could be a form of a macro virus that spreads itself to all the contacts located in the host’s email address book. If any of the e-mail recipients open the attachment of the infected mail, it spreads to the new host’s address book contacts and then proceeds to send itself to all those contacts as well. There are many ways in which a virus can infect document our PC. However, whether active or document, it’s dangerous to let loose on your system, and should be dealt with immediately.

Read More: What is Cyber Crime in Computer with Example

  • Trojan Horse

Trojan Horses are impostor files that claim to be something desirable but, in fact, are malicious. Rather than insert code into existing files, a Trojan horse appears to do one thing like install a screen sever or show a picture inside an e-mail. When in fact it does something entirely different, and potentially malicious, such as case files. Trojans can also open back so that computer hackers can gain access to passwords and other personal information stored on a computer.

Although often referred to as such, Trojan horses are not viruses in strict because they can not replicate automatically. For the Trojan horse to spread, it must be invited onto a computer by the user opening an email attachment or downloading and running a file from the Internet, for example.

  • Worm

A worm is a piece of software that uses computer networks and security flaws to create copies of itself. A copy of the worm will scan the network for any other machine that has a specific security flaw. It replicates itself to the new machine using the security flaw, and then being scanning and replicating a new worm.

Worms are programs that replicate themselves from system to system without the use of a host file. This is in contrast to viruses, which require the spreading of an infected host file. Although worms generally exist inside of other files, often Word or Excel documents, there is a difference between how worms and viruses use the host file. Usually, the worm will release a document that already has the “worm” macro inside the document. The entire document will travel from a computer virus to a computer, so the entire document should be considered the worm.

Examples of worms Viruses are Mydoom or ILOVEYOU 

  • Other malicious software

Earlier, the only way a computer was at risk was when you inserted an infected floppy. With the new age of technology, almost every computer is interconnected to the rest of the world at some point or the other, so it’s difficult to pinpoint the source and/or time of the infection. As if that weren’t bad enough, new-age computing has also brought about a new breed of malicious software. Today, the term ‘virus’ has become a generic term used for all the different ways that your computer can be attacked by malicious software. Besides the type of viruses, we mentioned here’s a look at some of the newer problems we face today.

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