Computer virus definition and virus characteristics

Definition of computer virus

Computer virus is a destructive and infectious ability of the program, and other normal procedures, when a computer virus from a certain way into the person, it will automatically enter the relevant procedures, destroy existing information, to replicate themselves, destroying the normal operation of the program. Mountains are like microbes in viruses. Both reproductive power and destructive, so people are known as "computer viruses."

There is no definitive conclusion about the exact definition of computer virus. The following is a simple definition given by the author of this book: computer viruses are a special, harmful program that is programmed by a malicious programmer, which is in the process of running a computer system. It can carry out hidden, parasitic, invasive and contagious functions.

The above definition is supplemented by the following:

1, hidden to increase the destructive power, computer viruses generally have a hidden, usually it can make the computer surface work normally, not by the computer users to detect, only in a certain condition suddenly attack, destroy the computer information.

2, parasitic computer viruses usually do not exist alone, but "sticky" in the (parasitic) some normal program body, so that people can not be "a knife excision."

3, the infringement refers to the computer information or settings to increase, delete, change. In addition, the virus occupies the storage space, the competition control power causes the computer to run slowly, even causes the system to be paralyzed.

4. Infection is the process by which a virus replicates itself from one program to another. The copied version is passed to another program or computer system, and in the process of copying, the form can also mutate.

The characteristics of computer viruses

Understanding the characteristics of computer viruses is very important to prevent computer viruses.

Typically, viruses have two states: static and dynamic. In general, the virus that exists on the hard disk is static, and the static virus takes up some of the storage space. It will not exhibit other destructive effects. When the virus completes the initial boot, enters the human memory, then is in the dynamic, under certain condition, will carry on the destruction, the infection and so on behavior

(1) Destructive

Destructive refers to the characteristics of a computer virus that destroys files or data and disrupts the normal functioning of the system. After computer virus infection system, it will affect the operation of operating system to different degree, light interferes user's work, heavy destroys computer system.

(2) Infectious

Infectivity refers to the characteristic of a computer virus to infect other programs with its own copy. Infectivity is the most important characteristic of computer virus, it is the basis of judging whether a piece of program code is a computer virus. After running a program that is infected with a PC, you can quickly infect other programs to infect Spread to different computers, computer networks. At the same time, the infected computer programs, computers, computer networks become the living environment of computer viruses and new sources of infection.

(3) Latent

Computer viruses have the ability to cling to other media and be parasitic. Depending on the parasitic power of the virus, the virus is transmitted to legitimate programs and systems. It may be a long period of time to ask will not attack, there is often a period of incubation. This characteristic of a virus is called latency. This feature of the virus is to conceal itself and then infect it without the user noticing it. .

(4) Concealment

This is another feature of computer viruses. Computer virus is a very high programming skills, short and simple executable program. But generally do not exist independently, but the use of embedded methods parasitic in a legitimate program. Some virus programs are hidden in the boot sector of the disk, or in sectors that are marked as bad clusters on the disk, and in sectors with larger idle probabilities. This is the illegal storage of the virus. The virus tries to hide the white body, and after satisfying certain conditions, the virus appears to be destructive, causing serious damage.

(5) Variant of

Computer viruses can produce variants in the course of development and evolution. Some viruses can produce dozens of of variants. A virus that has the ability to deform can conceal itself in the process of transmission. Make it difficult to be detected and purged by anti-virus programs.

(6) can trigger

Computer viruses generally have one or several trigger conditions, once the trigger condition is met, the infection mechanism of the virus can be activated to infect it, or to activate the part of the virus (forcibly displaying some text or images) or to destroy the part ' initiate an attack '. The essence of the trigger is a condition control, the virus program can be based on the requirements of the designer To implement an attack when the condition is satisfied. This condition can be a specific character, or a specific date or a specific time, or disease. The poison built-in counter reaches a certain number of times.

In addition to some of the above features, the current computer virus because of the development of related technologies and has some new features, for example, the virus spread through the network, spread, transmission speed is very fast, difficult to control; there are many variants of the virus. Because many of the virus programs are in Sichuan script language, it is easy to be modified to generate a lot of Many viruses are difficult to cure, and can easily cause multiple outbreaks. Therefore, with the computer virus is the most important and the road far.

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