Understand A computer virus that you might concerned

A computer virus is a type of malware that, once executed, replicates by altering other computer programs and inserting its own code into them. When this replication is successful, the affected areas are considered "infected" with the virus, a term borrowed from biological viruses.

Computer viruses typically require a host program. The virus embeds its code into the host program, and when the program is run, the virus is executed first, leading to infection and potential damage. In contrast, a computer worm does not need a host program, as it operates independently. Since it isn't tied to a specific program, a worm can run on its own and actively carry out attacks.

Virus creators often use social engineering tactics and exploit known security vulnerabilities to infect systems and propagate their malware. Viruses employ advanced anti-detection and stealth techniques to evade antivirus software. The motives behind creating viruses vary, ranging from financial gain (such as with ransomware), sending political messages, personal entertainment, showcasing software vulnerabilities, to causing sabotage or denial of service. Others may simply be exploring cybersecurity issues, artificial life, or evolutionary algorithms.

By 2013, computer viruses were causing billions of dollars in economic damage annually. In response, the antivirus industry emerged, offering both paid and free protection solutions to users of various operating systems.

The first academic work on the concept of self-replicating computer programs was conducted in 1949 by John von Neumann, who delivered lectures at the University of Illinois on the "Theory and Organization of Complicated Automata." Von Neumann's work was later published as the "Theory of Self-Reproducing Automata," in which he described how a computer program could be designed to reproduce itself. Von Neumann's design for a self-replicating computer program is considered the first computer virus, and he is regarded as the theoretical "father" of computer virology.

In 1972, Veith Risak, building directly on von Neumann's work, published his article "Selbstreproduzierende Automaten mit minimaler Informationsübertragung" (Self-reproducing automata with minimal information exchange). This article described a fully functional virus written in assembler language for a SIEMENS 4004/35 computer system. In 1980, Jürgen Kraus wrote his thesis "Selbstreproduktion bei Programmen" (Self-reproduction of programs) at the University of Dortmund, where he proposed that computer programs can behave similarly to biological viruses.

The MacMag virus, known as 'Universal Peace,' appeared on a Mac in March 1988. However, the first computer virus detected was the Creeper virus, which surfaced on ARPANET, the precursor to the Internet, in the early 1970s. Creeper was an experimental self-replicating program created by Bob Thomas at BBN Technologies in 1971. It used the ARPANET to infect DEC PDP-10 computers running the TENEX operating system, displaying the message, "I'M THE CREEPER. CATCH ME IF YOU CAN!" A program called Reaper was later developed to remove Creeper.

In 1982, the "Elk Cloner" virus was the first personal computer virus to spread "in the wild"—outside of the isolated environment where it was developed. Created by Richard Skrenta, a ninth grader at Mount Lebanon High School near Pittsburgh in 1981, it attached itself to the Apple DOS 3.3 operating system and spread via floppy disk. After 50 uses, the virus would activate, infecting the computer and displaying a short poem starting with, "Elk Cloner: The program with a personality."

In 1984, Fred Cohen from the University of Southern California wrote a paper titled "Computer Viruses – Theory and Experiments," the first to refer to a self-replicating program as a "virus." The term "virus" was suggested by Cohen's mentor Leonard Adleman. In 1987, Cohen demonstrated that no algorithm could perfectly detect all possible viruses. Cohen's theoretical compression virus was an example of a non-malicious virus, intended to be benevolent. However, antivirus professionals reject the concept of "benevolent viruses," as even well-meaning functions can be implemented without using a virus. Any virus, by definition, makes unauthorized changes to a computer, which is undesirable even if no harm is intended. Dr. Solomon's Virus Encyclopaedia explains the problems associated with viruses, even those that simply reproduce.

In 1984, J.B. Gunn published an article titled "Use of Virus Functions to Provide a Virtual APL Interpreter Under User Control," which described "useful virus functionalities." The first IBM PC-compatible virus to appear "in the wild" was a boot sector virus called (c)Brain, created in 1986 and released in 1987 by Amjad Farooq Alvi and Basit Farooq Alvi in Lahore, Pakistan, to prevent unauthorized copying of their software. The first virus to specifically target Microsoft Windows, WinVir, was discovered in April 1992, two years after Windows 3.0 was released. It did not rely on Windows API calls but instead used DOS interrupts. In February 1996, the Bizatch virus (also known as the "Boza" virus) was created by Australian hackers from the virus-writing group VLAD, becoming the first known virus to target Windows 95. By late 1997, the encrypted, memory-resident stealth virus Win32.Cabanas was released, the first virus to target Windows NT, although it could also infect Windows 3.0 and Windows 9x systems.

Even home computers were not immune to viruses. The first virus detected on the Amiga was a boot sector virus called the SCA virus, identified in November 1987.