Viruses are a special kind of computer program that contains so-called malicious code. The classification of computer viruses, which will be discussed below, is very extensive. One thing is for sure - a characteristic feature of all malicious programs is their ability to reproduce. Among other things, viruses are dangerous in that they are able to perform various arbitrary actions without the knowledge of the user, thereby harming the computer software.
So, computer viruses. Their classification is somewhat reminiscent of a thorough and detailed systematization of biological prototypes. Computer viruses need to be brought to a specific system. This can be done by taking the following characteristic features as a basis:
- habitat;
- a method of infection of this same habitat;
- various kinds of destructive capabilities;
- characteristic features of the mechanism of action of the virus.
Now I’ll talk about each feature in more detail.
Habitat. Computer virus classification
They should be divided into the following categories:
File viruses. They have the ability to embed themselves in operational files. For example, *. BAT, * .DLL, *. SYS, *. EXE, *. COM.
Boot viruses. They invade the disk boot sector (Boot sector) or in a special sector, which includes the system bootloader of the hard disk, the so-called Master Boot Record.
Macro viruses. They are installed inside the system and use so-called macros (for example, Excel, Word).
Also, one should not forget that combined viruses exist. As a rule, they belong to the file-boot type and infect not only the files themselves, but also the boot sectors. In most cases, such viruses have a rather complex mechanism of action, and are often designed in such a way as to penetrate the system as original as possible, in order to prevent their rapid detection.
Ways of infection. Computer virus classification
Resident. In RAM leave their resident part. She after some time begins to completely control the operating system. These viruses remain active until the device is rebooted or turned off.
Non-resident. They are practically an exact copy of the previous ones, but they do not infect the memory, and only a certain, usually limited, period of time remains active.
Classification of computer viruses, given their destructive capabilities
Harmless. Absolutely not affect the operation of the device. The only negative is that they spread very quickly and reduce the amount of free memory on the hard drive.
Non-hazardous. They affect the amount of free memory, and can also attract attention with various effects, usually sound or graphic.
Dangerous. Cause serious malfunctioning systems.
Extremely hazardous. They lead to the loss of various programs, destroy data, erase the information necessary for the full operation of the device.
Types of computer viruses depending on its mechanism of action
Companion viruses. Create satellite files for exe files. The name remains the same, but the extension changes to COM. As a rule, when starting a file of this kind, DOS will first detect and execute the COM file, i.e. virus.
Viruses are worms. They are one of the variants of companion viruses. Create their own copies, the COM-EXE technique is not applied.
Parasitic malware. This includes all those viruses that for some reason cannot be attributed to either the first or second sections of this group.
Network viruses. They are famous for their ability to get into a computer through a network and send out their copies. Do not access device resources.
Polymorphic viruses. They do not contain a permanent stake, they are constantly changing, therefore they are classified as those that are difficult to detect.
Macro viruses. Programs that are written in any one specific language infect.