Computer Virus hazards and symptoms

When it comes to computer viruses in the early stages, computer viruses often focus on the direct impact of viruses on information systems, such as formatting.
Hard Disk, delete file data, and distinguish between virus and virus. In fact, these are only part of the virus.
People are deeply aware that all viruses may cause serious damage to computer information systems.

Major Hazards of computer viruses
The main dangers of computer viruses include:

1. The direct destruction of computer data by virus Excitation
Most viruses directly destroy important information data of the computer when it is triggered. The methods used include formatting the disk, rewriting the File Allocation Table and directory.
Partition, delete important files, use meaningless "junk" data to rewrite files, and destroy CMO5 settings.
The disk KILLER virus (D1SK KILLER) contains a counter that is triggered within 48 hours after the disk is infected with viruses.
"Warning!" is displayed !! Dontturn off power or remove diskette while Disk Killer is Prosessing !" (Alert
Notice! D1SK KILLER ll1 is working, do not power off or take out the disk), rewrite the hard disk data. The hard drive damaged by D1SK KILLER can use anti-virus
Do not give up software repair.

2. disk space and information destruction
Viruses Infected with the disk always occupy part of the disk space illegally.
Generally, the virus occupies the Boot Sector of the disk, and transfers the original boot zone to other sectors, that is, the boot sector.
The virus needs to overwrite one disk sector. The data in the covered slice is permanently lost and cannot be recovered.
File viruses use some DOS functions for transmission. These DOS functions can detect unused disk space and write the infected part of the virus to the disk.
Unused parts. Therefore, during the transmission process, the original data on the disk is not damaged, but the disk space is illegally occupied. Some file-type viruses are very contagious.
Fast, infected with a large number of files in a short period of time, each file is extended to varying degrees, resulting in a serious waste of disk space.

3. Seize system resources
Except for a few viruses such as VIENNA and CASPER, most of the other viruses are resident memory dynamically, which must seize part of system resources. Disease
The basic memory used by the virus is roughly the same as the virus. Viruses occupy the memory, resulting in reduced memory, and some software cannot run. In addition to occupied space
Out of memory, the virus also preemptively interrupts and interferes with system operation. Many functions of the computer operating system are implemented through the interrupt call technology. Virus for infection
Sending, always modify some related interrupt address, add virus "private goods" during normal interruption, thus interfering with the normal operation of the system.

4. affecting computer running speed
After the virus enters the memory, it not only interferes with the system operation, but also affects the computer speed, mainly manifested in:
(1) The virus always monitors the computer's working status in order to determine the exposure conditions of the infection, which is redundant compared with the normal running status of the computer.
Harmful.
(2) Some viruses not only encrypt the static viruses on the disk, but also the dynamic viruses in the memory are encrypted to protect themselves.
When addressing a virus, run a decryption program to decrypt the encrypted virus into a valid CPU command and run it again.
Re-encrypt the virus. In this way, the CPU executes thousands or even tens of thousands of commands.
(3) When a virus is infected, it also needs to insert illegal additional operations. In particular, when a floppy disk is infected, not only the computer speed slows down significantly, but also the soft disk becomes normal.
Frequent read/write orders are disrupted, making Harsh noises.

5. Computer Virus errors and unforeseen dangers
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,
Material resources, after a long period of debugging and improvement, the software can be launched. But in the opinion of virus compilers, there is no need or possibility to do so. Many Computers
A virus is thrown out after being compiled and debugged by someone else on a computer. Anti-virus experts analyzed a large number of viruses and found that most of them existed.
Errors of different degrees.
Another major source of the error virus is the variant virus. Some new computers do not yet have the ability to compile software independently, for curiosity or other reasons
Modify others' viruses and cause errors.
The consequences of computer virus errors are often unpredictable. Anti-Virus workers once pointed out that the Black Friday virus has nine errors.
There are five errors in the virus. However, it is impossible for people to spend a lot of time analyzing thousands of virus errors. Spread of a large number of viruses containing unknown errors
The consequences are unpredictable.

6. 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.
The operating conditions are "fat and thin", and the model and operating system version are required. Virus
Generally, compilers do not test viruses in various computer environments. Therefore, virus compatibility is poor, which often causes
Crash.
7. Computer Viruses cause severe psychological pressure on users
According to statistics from related computer sales departments, after-sales computer users suspect that "computers have viruses" and ask for advice, which accounts for more than 60% of the after-sales service workload.
It is detected that there are about 70% of viruses, and another 30% cases are only suspected by users. In fact, computers do not have viruses. The user is suspicious of the virus.
Why? Most of them are computer crashes and software running exceptions. These phenomena are indeed very likely caused by computer viruses. However
Not all. In fact, when a computer is "abnormal", it is difficult for a common user to accurately determine whether it is a virus. Most users are infected with viruses
Taking a trusted attitude is undoubtedly necessary to protect computer security. However, it often takes time, money, and other costs. Only
It is even more difficult to compensate for the loss caused by accidental disk formatting. Not only individual standalone users, but also some large network systems will inevitably be screened
Shut down due to virus. In short, computer viruses are shrouded in the hearts of many computer users like "ghosts", causing great psychological pressure and great impact to people.
Because of the efficiency of modern computers, the intangible loss caused by this is immeasurable.