To prevent viruses, you must first understand the virus.

This article introduces the scientific, systematic, and rigorous classification methods of computer viruses.

As we all know, viruses are actually human-prepared malignant programs. Computer viruses have scientific, systematic, and rigorous classification methods. We will introduce them to you:

Based on the damage ability of the virus, it can be divided into the following types:

The harmless model has no impact on the system except reducing the available disk space during transmission.

No-risk viruses only reduce memory, display images, sound and sound.

Dangerous Viruses cause serious errors in computer system operations.

Very dangerous viruses such as program deletion, data destruction, clearing system memory areas and important information in the operating system.

The harm these viruses cause to the system is not a dangerous call in their own algorithms, but an unpredictable and catastrophic damage when they are infected. Errors caused by viruses in other programs can also damage files and sectors. These viruses are also divided according to their damage capabilities. Some current harmless viruses may also damage the new DOS, Windows, and other operating systems. For example, in an early virus, a "Denzuk" virus works well on a kb disk without causing any damage, however, the subsequent high-density floppy disk may cause a large amount of data loss.

According to the unique algorithms of viruses, viruses can be classified as companion viruses and worms:

The companion virus type does not change the file itself. They generate the companion body of the EXE file based on the algorithm and have the same name and different extensions (COM), for example: xcopy.exe is accompanied by Xcopy.com. The virus writes itself into the COM file without changing the EXE file. When the DOS loads the file, the companion body is preferentially executed, and then the companion body is loaded to execute the original EXE file.

Worms spread over computer networks without changing the file and data information. They use the network to spread from the memory of one machine to the memory of other machines and calculate the network address, send your own viruses over the network. Sometimes they exist in the system. Generally, they do not occupy other resources except the memory.

Apart from companion and worm viruses, other viruses can be called parasitic viruses. They are attached to the system's boot sector or file and spread through the system's functions. They can be divided:

The exercise virus itself contains errors and cannot spread well. For example, some viruses are in the debugging stage.

Classified Viruses generally do not directly modify DOS interrupt and sector data. Instead, they use device technologies, file buffers, and other internal DOS modifications to make it difficult to see resources and use advanced technologies. Use the idle data zone of DOS for work.

The variant virus is also known as the ghost virus. This type of virus uses a complex algorithm, so that each copy of the virus has a different content and length. They generally consist of a decoding algorithm mixed with irrelevant instructions and a changed virus.