The main targets of computer virus damage are "programs and data". A computer virus refers to a set of computer instructions or program codes compiled or inserted into a computer program that destroy computer functions or data, affect computer use, and are capable of self-replication.
The operating environment of this tutorial: Windows 7 system, Dell G3 computer.
The main targets of computer virus damage are "programs and data".
Computer Virus is a set of computer instructions or program codes that the programmer inserts into a computer program to destroy computer functions or data. It can affect the use of the computer and can replicate itself.
Computer viruses are artificially created, destructive, contagious and latent programs that damage computer information or systems. It does not exist independently, but is hidden in other executable programs. When a computer is infected with a virus, it may affect the running speed of the machine at first, or crash and damage the system at worst. Therefore, the virus brings great losses to the user. Under normal circumstances, we call this destructive program a computer virus.
Computer viruses are contagious, covert, infectious, latent, excitable, expressive or destructive. The life cycle of a computer virus: development period → infection period → incubation period → attack period → discovery period → digestion period → extinction period.
Features:
Any virus that invades the system will have varying degrees of impact on the system and applications. In mild cases, it will reduce computer work efficiency and occupy system resources. In severe cases, it can cause data loss and system crash. The programmatic nature of a computer virus means that it is an executable program like other legal programs. However, it is not a complete program, but a program that is parasitic on other executable programs. The virus only becomes active when other programs are running. Play a destructive role. Once the virus enters the computer and is executed, it will search for other qualified environments, determine the target, and then control itself in it to achieve the purpose of self-reproduction. Therefore, infectivity is an important condition for judging computer viruses.
The virus will cause fatal damage to the computer only when its specific conditions are met. The computer or system will not react immediately after being poisoned, and the virus will remain hidden in the system for a long time. For example, the most unforgettable one is the CIH attack on the 26th. In addition, there is the famous "Black Friday" attack on every Friday the 13th, etc. Viruses are usually attached to normal hard drives or programs, and it is difficult for computer users to detect them before they are activated. They are programmed using very high programming skills. They are short and concise executable programs that have a devastating effect on computers; Generally, no user actively executes a virus program, but the virus will take effect when its conditions mature, or destroy the program, disrupt the work of the system, etc. The unauthorized operation of the computer is a typical feature of computer viruses, which will occur without the operator's control. run automatically with permission.
Concealment:
Computer viruses are not easy to detect. This is because computer viruses have strong concealment and often exist in the form of hidden files or program codes. In ordinary viruses, During the inspection and killing, it is difficult to achieve timely and effective inspection and killing. Viruses disguise themselves as normal programs and are difficult to detect with computer virus scans. Moreover, some viruses are designed as virus repair programs to induce users to use them, thereby implanting viruses and invading computers. Therefore, the concealment of computer viruses makes computer security protection passive, causing serious security risks.
Destructiveness:
Viruses that invade computers are often extremely destructive. They can destroy data and information, and even cause large areas of computer paralysis, causing great losses to computer users. Computer viruses such as common Trojans and worms can invade computers on a large scale and bring security risks to computers.
Infectivity:
One of the major characteristics of computer viruses is their infectivity, and they can invade computers through U disks, networks, etc. After an invasion, the virus can often spread and infect uninfected computers, causing widespread paralysis and other accidents. With the continuous development of network information technology, viruses can achieve a wide range of malicious intrusions in a short period of time. Therefore, in the security defense of computer viruses, how to deal with rapid virus infection has become an important basis for effective defense against viruses and the key to building a defense system.
Parasiteness:
Computer viruses also have parasitic characteristics. Computer viruses need to be parasitic in the host to survive, in order to better perform their functions and destroy the normal functions of the host. Usually, computer viruses are parasitic in other normal programs or data, and then use certain media to spread. During the actual operation of the host computer, once certain setting conditions are reached, the computer virus will be activated. When the program is started, the computer virus will continuously assist and modify the host computer files so that its destructive effect can be exerted.
Executability:
Computer virus, like other legal programs, is an executable program, but it is not a complete program, but is parasitic on other executable programs, so it enjoys the rights that all programs can obtain.
Triggerability:
The virus is characterized by inducing the virus to infect or attack due to the occurrence of a certain event or value.
Activity of attack:
Viruses attack the system proactively. No matter how strict the protection measures taken by the computer system, it is impossible to completely eliminate virus attacks on the system, and protective measures At best, it is a preventive measure.
Virus targeting:
Computer viruses are targeted at specific computers and specific operating systems. For example: there are ones for IBM PCs and compatibles, there are ones for Apple's Macintosh, and there are ones for UNIX operating systems. For example, the ball virus is targeted at the DOS operating system on IBM PCs and compatible machines.
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