Hard disk, delete file data, etc. And to distinguish malignant viruses from benign viruses. In fact, these are only part of the virus's misdeeds. With the development of computer application,
Exhibition, people deeply realize that all viruses may cause serious damage to computer information systems.
The main harm of computer virus
The main hazards of computer viruses are:
1. The direct destruction of computer data information by virus excitation.
Most viruses directly destroy the important information and data of the computer when they are excited. The methods used include formatting the disk and rewriting the file allocation table and directory.
Area, delete important files or rewrite files with meaningless "junk" data, destroy CMO5 settings, etc.
Hard disk killer virus (D 1SK KILLER) contains a counter, which is activated within 48 hours after hard disk infection and displayed on the screen when activated.
Display "Warning! ! Please don't turn off the power or take out the disk when the black disk is running! "(p
Sue! D 1SK KILLER ll 1 is working, don't turn off the power or take out the disk), overwrite the hard disk data. D 1SK killer's damaged hard disk can be disinfected.
Software repair, do not give up easily.
2. Occupy disk space and damage information
Viruses parasitic on the disk always occupy a part of the disk space illegally.
The general occupation mode of boot virus is that the virus itself occupies the boot sector of the disk and transfers the original boot sector to other sectors, that is, boot type.
A virus can overwrite a disk sector. Overwritten sector data will be permanently lost and cannot be recovered.
The file virus is infected by some DOS functions, which can detect the unused space on the disk and write the infected part to the disk.
Go to the unused section. Therefore, in the process of infection, the original data on the disk is generally not destroyed, but the disk space is illegally occupied. Some files are highly contagious.
Infected a large number of files in a short time, each file has different degrees of elongation, resulting in a serious waste of disk space.
3. Seize the system resources
Except for a few viruses such as VIENNA and CASPER, most other viruses reside in memory dynamically, which will inevitably seize some system resources. disease
The basic memory length occupied by a virus is roughly equivalent to the length of the virus itself. The virus preempted the memory, resulting in memory reduction, and some software could not run. In addition to career.
In addition to memory, viruses will preempt interrupts and interfere with system operation. Many functions of computer operating system are realized by interrupt calling technology. The virus is excited by infection.
Hair, always modify some related interrupt addresses, and add virus "boot program" in the normal interrupt process, thus interfering with the normal operation of the system.
4. Affect the running speed of the computer
After the virus enters the memory, it not only interferes with the system operation, but also affects the speed of the computer, mainly in the following aspects:
(1) virus has been monitoring the working state of the computer in order to judge the infection excitation conditions, which is unnecessary compared with the normal running state of the computer.
And harmful.
(2) In order to protect themselves, some viruses not only encrypt the static virus on the disk, but also encrypt the dynamic virus after entering the memory. cpu
Every time the virus is addressed, a decryption program should be run to decrypt the encrypted virus into legal CPU instructions before execution; And it will take a while for the virus to run.
Re-encrypt the virus sequence. In this way, the CPU executes thousands or even tens of thousands of instructions.
(3) When the virus is infected, illegal extra operations should be inserted, especially when the floppy disk is infected, not only the computer speed is obviously slow, but also the floppy disk is positive.
The usual reading and writing order was disrupted, making a harsh noise.
5. Computer virus errors and unforeseen dangers
A big difference between computer viruses and other computer software is that viruses are irresponsible. Writing a perfect computer software requires a lot of manpower.
Material resources, after a long period of debugging and improvement, the software can be online. But it is not necessary and impossible for virus makers to do so. Many computers
After someone hastily compiled and debugged the virus on the computer, the virus was thrown out. After analyzing a large number of viruses, anti-virus experts found that most of them existed.
Different degrees of mistakes.
Another major source of error viruses is mutant viruses. Some beginners don't have the ability to compile software independently, out of curiosity or other reasons.
Modify other people's viruses, causing errors.
The consequences of computer virus errors are often unpredictable. Anti-virus workers have pointed out nine errors of Black Friday virus in detail.
Pong virus has five errors and so on. But people can't spend a lot of time analyzing thousands of virus errors. A large number of unknown errors spread by viruses.
Broadcast, the consequences are unpredictable.
6. The influence of computer virus compatibility on system operation.
Compatibility is an important index of computer software. Software with good compatibility can run in various computer environments, while software with poor compatibility is right.
Operating conditions are "optional" and require model and operating system version. viral
Compilers generally do not test viruses in various computer environments, so virus compatibility is poor, which often leads to
Collapse.
7. Computer virus has caused serious psychological pressure to users.
According to the statistics of relevant computer sales departments, after-sales users of computers suspect that "the computer has a virus" and make inquiries, accounting for more than 60% of the after-sales service workload.
About 70% of them were found to have viruses, and 30% were only suspected by users, but in fact, the computer did not have viruses. Then the user suspects that it is a virus.
What is the reason? Most of them are computer crashes and abnormal software operation. These phenomena may indeed be caused by computer viruses. But once again,
Not exactly. In fact, in the case of "abnormal" computer, it is difficult to ask an ordinary user to accurately judge whether it is caused by a virus. Most users are interested in viruses.
It is undoubtedly necessary to adopt an attitude of believing in what it has, but it often takes time and money. only
The loss caused by the suspected virus rashly formatting the disk is even more irreparable. Not only individual stand-alone users, but also in some large network systems.
Virus and shut down. In a word, computer virus hangs over the minds of computer users like a "ghost", causing great psychological pressure and great influence.
The use efficiency of modern computers has improved, and the intangible losses caused by it are incalculable.