The harm caused by computer viruses to the operating system is mainly manifested in

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.

The main hazards of computer viruses are: (Recommended learning: PHP video tutorial)

1. The direct destructive effect of virus activation on computer data and information

Most viruses directly destroy important computer information and data when activated. The methods used include formatting disks, rewriting file allocation tables and directory areas. , delete important files or overwrite files with meaningless "junk" data, destroy CMO5 settings, etc.

2. Occupying disk space and damaging information

Viruses parasitic on the disk will always illegally occupy part of the disk space.

The general intrusion method of boot viruses is that the virus itself occupies the boot sector of the disk and transfers the original boot sector to other sectors, that is, the boot virus overwrites one disk sector. The overwritten sector data is permanently lost and cannot be recovered.

File-type viruses use some DOS functions to infect. These DOS functions can detect the unused space of the disk and write the infected part of the virus to the unused part of the disk. Therefore, the original data on the disk is generally not destroyed during the infection process, but the disk space is illegally occupied. Some file-type viruses infect very quickly, infecting a large number of files in a short period of time, and each file is lengthened to varying degrees, causing a serious waste of disk space.

3. Seize system resources

Except for a few viruses such as VIENNA and CASPER, most other viruses are resident in memory under dynamic conditions, which will inevitably seize some system resources. The basic memory length occupied by the virus is roughly the same as the length of the virus itself. The virus seizes memory, causing the memory to be reduced and some software to be unable to run. In addition to occupying memory, viruses also seize interrupts and interfere with system operation. Many functions of the computer operating system are implemented through interrupt calling technology. In order to cause infection, viruses always modify some relevant interrupt addresses and add the virus' "private goods" during the normal interrupt process, thus interfering with the normal operation of the system.

4. Affecting the computer's running speed

After the virus enters the memory, it not only interferes with the system operation, but also affects the computer speed. The main manifestations are:

(1) In order to determine the infection triggering conditions, the virus must always Monitoring the working status of the computer is redundant and harmful relative to the normal operating status of the computer.

(2) In order to protect themselves, some viruses not only encrypt the static viruses on the disk, but also encrypt the dynamic viruses after entering the memory. The CPU must run a decryption process every time it addresses the virus. The program decrypts the encrypted virus into legal CPU instructions and then executes it; when the virus is finished running, a program is used to re-encrypt the virus. In this way, the CPU executes thousands or even tens of thousands of additional instructions.

(3) The virus also inserts illegal additional operations when infecting. Especially when infecting a floppy disk, not only the computer speed is significantly slowed down, but the normal reading and writing order of the floppy disk is disrupted, making a harsh noise.

5. Computer virus errors and unforeseen harm

One major difference between computer viruses and other computer software is the irresponsibility of viruses. Compiling a complete computer software requires a lot of manpower and material resources. After a long period of debugging and improvement, the software can be launched. But in the opinion of virus compilers, this is neither necessary nor possible. Many computer viruses are hurriedly programmed and debugged by individuals on a computer and then thrown out. After analyzing a large number of viruses, anti-virus experts have found that most viruses have varying degrees of errors.

Another major source of erroneous viruses is variant viruses. Some computer beginners who do not have the ability to independently compile software modify other people's viruses out of curiosity or other reasons, causing errors.

The consequences of computer virus errors are often unpredictable. Anti-virus workers once pointed out in detail that there were 9 errors in the Black Friday virus and 5 errors in the Ping Pong virus. But it is impossible for people to spend a lot of time analyzing the errors of tens of thousands of viruses. A large number of viruses containing unknown errors spread, and the consequences are unpredictable.

6. The impact of computer virus compatibility on system operation

Compatibility is an important indicator of computer software. Software with good compatibility can run in various computer environments, whereas software with poor compatibility can The operating conditions are "picky", requiring the model and operating system version, etc. Virus compilers generally do not test viruses in various computer environments, so viruses have poor compatibility and often lead to crashes.

7. Computer viruses cause serious psychological pressure to users

According to statistics from relevant computer sales departments, computer after-sales users who suspect "the computer has a virus" and make inquiries account for more than 60% of the after-sales service workload.

Approximately 70% of the cases have been tested and there is indeed a virus, and the other 30% are just suspected by the user, but in fact there is no virus on the computer. So what are the reasons why users suspect viruses? Most of the time, phenomena such as computer crashes and abnormal software operation occur. These phenomena are indeed likely to be caused by computer viruses. But not entirely. In fact, when the computer is working "abnormally", it is difficult to ask an ordinary user to accurately judge whether it is caused by a virus. Most users prefer to believe viruses, which is undoubtedly necessary to protect computer security. However, it often costs time, money, etc. The damage caused by rashly formatting the disk simply because of suspicion of a virus is even more difficult to make up for. Not only individual stand-alone users, but also some large network systems will inevitably have to shut down for virus screening.

In short, computer viruses hang over the minds of computer users like "ghosts", causing huge psychological pressure on people and greatly affecting the efficiency of modern computers. The intangible losses caused by this are inestimable. .

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