What is a Computer Virus?

What is a Computer Virus?

Once it has been placed on a user’s computer, a computer virus is a type of malware that affixes itself to another application and has the ability to replicate and spread.What is a Computer Virus?  A computer is considered to be infected by a virus when it alters how it should operate normally. A computer may contract this infection from another. For instance, you can unintentionally open a malicious email attachment that was sent to you, causing your computer to get infected. Or, to put it another way, a virus is a destructive software program that infects a computer without the user’s knowledge or consent and then carries out some malicious deeds.

Once it has infected the system, a virus attaches to another piece of software in such a way that when the host application is executed, the virus’s functions are also activated. It has the capacity to replicate itself, infecting other software or data files in the process. Computer viruses can be destructive, but the bulk of them carry out malicious acts like erasing data.

History of Computer Virus:


For a very long time, viruses have been using the Internet or some other means to infect numerous gadgets. The viruses are made with the purpose of stealing data, obliterating the device, etc. An experimental self-Multiplying virus called “Creeper system,” the first computer virus, was released in 1971. Then, in the middle of the 1970s, the extraordinarily aggressive Rabbit virus appeared. It copied itself quickly and ruined functioning at the same time. Rich Skrenta created “Elk Cloner,” the first computer virus, in 1982. It propagated through a game-containing floppy disc and attached 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.

Types of Computer Viruses: 

  • Resident Virus: The way viruses spread is through infecting host computer software. By infecting apps as they are opened by a user, a resident virus does this. When no programs are operating, executable files can be infected by a non-resident virus.
  • Multipartite Virus: A multipartite virus infects and spreads across computers using a variety of strategies. Usually, it stays in the computer’s memory until it infects the hard drive, then spreads by changing the apps’ contents to infect further discs. Performance lag and low application memory are the results of this.

    By not opening attachments from unknown sources and by using reputable antivirus software, multipartite viruses can be prevented. Cleaning the computer’s full drive and the boot section can also stop it.

  • Direct Action: A direct action virus gains access to the main memory of a computer and spreads infection to all applications, files, and directories in the autoexec.bat path before erasing itself. Although this virus usually degrades a system’s performance, it is also capable of wiping out all the data on a computer’s hard drive and any USB devices that are connected to it. By using antivirus scanners, direct-action viruses can be prevented. They are simple to spot and recover corrupted files.

  • Browser Hijacker: An application called a “browser hijacker” alters the default settings of online browsers, such as the homepage, new tab page, and default search engine. Technically speaking, it is not a virus because it cannot corrupt data, but it can cause a great deal of harm to computer users because they frequently cannot change their homepage or search engine. The adware that generates unwanted pop-ups and adverts may also be present.

    Use only reputable apps and antivirus software, as browser hijackers generally attach to freeware and dangerous programs from untrusted websites or app stores.

  • Overwrite Virus: Overwrite viruses can be quite harmful. They have the ability to remove data and replace it with their own code or file content. The virus can harm Windows, DOS, Linux, and Apple systems, and once files are infected, they cannot be replaced. This infection can only be eliminated by erasing every affected file, which could have disastrous consequences. Using a reliable antivirus program and keeping it updated is the best defense against the overwritten virus.

  • Web Scripting Virus: A web scripting virus compromises the security of web browsers, allowing a hacker to insert client-side scripting or harmful code into online pages. Because of this, egregious websites can be attacked, including social networking sites, email services, and any website that accepts user comments or reviews. The virus can be used by attackers to deliver spam, carry out fraud, and harm server files.

    Real-time web browser protection software, cookie security, script disablement, and malware cleanup tools are all necessary for web scripting defense.

  • File Infector: One of the most prevalent computer viruses is a file infector. When files are opened, it overwrites them, and it spreads fast through networks and computers. Files with the.exe or.com extension are primarily affected. The only effective defense against file infector viruses is to only download authorized software and use an antivirus program.

  • Network Virus: Because they have the ability to entirely disable entire computer networks, network viruses are exceedingly harmful. Since the virus could be concealed within any machine on an infected network, they are frequently challenging to find. By transferring to devices linked to the network via the internet, these viruses can readily proliferate and propagate. The best defense against network infections is the usage of dependable, powerful antivirus programs and cutting-edge firewalls.

  • Boot Sector Virus: A computer’s master boot record is the target of a boot sector virus (MBR). When a computer resumes, the virus injects its code into the partition table of the hard drive before moving into the main memory. Poor system performance, boot-up issues, and the inability to locate the hard disc are signs of the existence of the virus. The majority of contemporary computers are equipped with boot sector protections that limit the possibility of this kind of malware.

    Making sure discs are write-protected and refraining from turning on a computer with untrusted external devices plugged in are two precautions against a boot sector virus.

What does a computer virus do?

A virus can, among other things, damage or delete data, consume more system resources, and record keystrokes. During this process, a virus has the potential to have unexpected or negative results, such as erasing system software by corrupting data. Some computer viruses are created with the intention of harming your computer by erasing files, corrupting software, or reformatting the hard drive. Even less harmful computer infections can significantly affect how well your system performs by consuming RAM and causing frequent crashes. Other viruses might simply replicate themselves or overwhelm a network with traffic, making it difficult for anyone to use

What does a computer virus do?

Consider a scenario in which a virus has infected a computer application. (We’ll examine the different ways that could occur in a moment, but for the time being let’s simply assume infection.) How does the virus carry out its unsavoury tasks? The procedure is nicely described at a high level in Bleeping Computer. The typical process is as follows: the infected application runs (often at the user’s request), and the viral code loads into the CPU memory before any of the legitimate code does.

The virus now spreads itself by attacking additional programmes on the host computer and injecting harmful code everywhere it can. (A resident virus infects executable files even when they are not operating. A non-resident virus can infect executable files even when they are.) At this point, boot sector viruses employ a particularly evil tactic: they embed their code in the boot sector of the system disc of the computer, guaranteeing that it will be executed even before the operating system fully boots, making it impossible to operate the machine in a “clean” manner.

Once the virus has gained access to your computer, it can begin executing its payload—the section of the virus code that is responsible for carrying out the malicious tasks for which it was designed. These include a variety of unpleasant things: Viruses can track your keystrokes to steal passwords, convert your computer into a zombie that launches a DDoS attack against the hacker’s adversaries, scan your computer hard drive for banking credentials, encrypt your data, and then demand a bitcoin ransom to decrypt it.

Computer virus symptoms

How can you determine whether a virus has evaded your defences? With a few notable exceptions, such as ransomware, viruses are not eager to let you know they have infected your machine. A computer virus tries to cause damage in the background while your machine is still functioning, just as a biological virus seeks to keep its host alive so it may continue to utilise it as a vehicle for reproduction and spread. However, there are indicators that you are contaminated. Symptoms on Norton’s list are as follows:

  • Unusually slow performance
  • Frequent crashes
  • Unknown or unfamiliar programs that start up when you turn on your computer
  • Mass emails being sent from your email account
  • Changes to your homepage or passwords

A computer virus scan is necessary if you think your machine may be contaminated. There are many free services available to help you get started with your research: The Safety Detective has compiled a list of the top ones.

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