Shulou(Shulou.com)06/01 Report--

Virus: a set of computer instructions or program code that destroys computer function or data, affects computer use and can replicate itself, which is written or inserted in a computer program is called a computer virus (Computer Virus). Destructive, replicative and contagious.

Harmfulness:

1. Latent property

In general, after a computer virus infects the system, it does not immediately attack the computer, but has an incubation period for a period of time. The incubation period is generally determined by the trigger conditions set by the virus programmer.

two。 Infectivity

After the computer virus system, under certain conditions, destroy the defense function of the system itself, quickly replicate itself, and spread from the infected storage location to the uninfected storage location. virus transmission between computers can be carried out through the network.

3. Destructive

Once the computer system is infected with virus programs, the stability of the system will be affected to varying degrees. In general, when a computer virus breaks out, because of its continuous self-replication, most of the system resources are occupied, which slows down the running speed of the computer and makes it impossible for users to use it normally. In serious cases, the whole system can be paralyzed and can not be repaired, resulting in losses.

4. Concealment

Computer viruses usually exist in the form of programs that people are familiar with. Some virus names are often named similar to system file names. For example, one "n" of the Internet word is changed to two "n" by false icons, which is difficult for users to find. Once they click to visit the website pointed to by these icons, they are likely to face the threat of fishing or hanging horses. Another example is the folder EXE virus, whose icon is the same as the Windows default folder icon, which is very confusing. When the user double-clicks to open this folder, the virus will be activated.

5. Diversity

Because computer viruses have the characteristics of self-replication and transmission, coupled with the diversification of modern media, the development of computer viruses shows the characteristics of diversity in quantity and type.

6. Trigger

In general, after the computer virus invades the system, it does not occur immediately, but lurks in a program or disk more covertly. When the trigger condition determined by the virus program is reached, such as setting the date as the trigger condition, or setting the operation as the trigger condition, when the condition meets the preset, the virus program will execute automatically immediately, and continue to self-copy and infect other disks to destroy the system. For example, the March 25th virus is activated if it is in memory on March 25 of each year.

Virus characteristics:

(1) parasitic computer viruses are parasitic in other programs. when this program is executed, the virus plays a destructive role, but it is not easy to be detected until the program is started.

(2) Infectious computer virus is not only destructive, but also contagious. Once the virus is replicated or mutated, its speed is difficult to prevent. Infectivity is the basic characteristic of the virus. In the biological world, viruses spread from one organism to another through infection. Under the right conditions, it can be multiplied in large numbers, causing infected organisms to show symptoms or even death. Similarly, computer viruses can spread from infected computers to uninfected computers through various channels, causing the infected computers to malfunction or even paralyze in some cases. Unlike a biological virus, a computer virus is a piece of artificial computer program code. once this program code enters a computer well and is executed, it will search for other programs or storage media that meet its infectious conditions. after determining the target, you will insert your own code into it to achieve the purpose of self-reproduction.

(3) latent some viruses are like *. When to let it attack is designed in advance. For example, the Black Friday virus, which is not detected at all until the scheduled time, suddenly explodes and destroys the system when the conditions are in place. A well-written computer virus program usually does not break out immediately after entering the system, and can be hidden in legal files within weeks or months or even years to infect other systems without being discovered. The better the latent nature, the longer it will exist in the system, and the greater the spread of the virus. The first manifestation of latency is that a virus program cannot be detected without a special detection program, so the virus can quietly hide in a disk or tape for a few days or even years, once the time is ripe to get the opportunity to run. It will have to multiply, spread, and continue to do harm. The second manifestation of latent nature is that there is often a trigger mechanism inside the computer virus. When the trigger condition is not met, the computer virus does not do any damage except infection. Once the trigger conditions are met, some display information, graphics or special identifiers on the screen, while others perform operations that destroy the system, such as formatting the disk, deleting the disk file, encrypting the data file, locking the keyboard and deadlock the system.

(4) concealed computer viruses have strong concealment, some can be detected by virus software, some can not be detected at all, and some are sometimes hidden and changeable, and this kind of virus is usually very difficult to deal with.

(5) destructive computer poisoning may cause normal programs to fail to run, delete files in the computer or be damaged to varying degrees.

(6) the triggering characteristic of computer virus is called triggering due to the emergence of an event or numerical value. In order to conceal itself, the virus must lurk and do less action. If it does not move at all and lurks all the time, the virus can neither be infected nor destroyed, and it will lose its lethality. To conceal and maintain its lethality, the virus must be triggering. The trigger mechanism of the virus is used to control the frequency of infection and destruction. Viruses have predetermined trigger conditions, which may be time, date, file type, or some specific data. When the virus is running, the trigger mechanism checks whether the predetermined conditions are met, and if so, initiates the infection or destruction action to cause the virus to be infected or *; if not, the virus continues to lurk.

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