Perhaps there is no such person who would not know what a virus is. The dank autumn and frosty winter are the usual time for viral diseases. High body temperature, loss of vitality - all this is quite familiar and familiar. Doctors have long figured out what the virus is. This is the simplest living organism, causing the infected cell to reproduce its own copy. In fact, the cell itself, unwillingly, begins to produce new generations of the original virus. Studying what a virus is, it is often noticed that its structure is so primitive that such a living organism itself can be compared with ... a computer program. Indeed, the analogy is clearly traced. Any running program “makes” computer components work in accordance with the wishes of the programmer who created it. It was this similarity that served as the reason why a small section of the digital program code was called a computer virus.
Often you can hear the expression "laptop picked up a virus." What does this mean? Let's look at one very common situation. Once a friend came to the owner of the laptop and brought on the flash drive some information downloaded from the Internet. It can be a program, driver, system library. At the same time, the person does not even suspect that someone added a small section of the executable code to the binary code of the application. By launching such a modified file, the user sends the processor two programs at once - the main and the unnoticeable additional. Computer virus - this is the very supplement. An important point: its functioning does not appear externally. First, the added code is executed, and only then - the main one. Once in the RAM, the virus, as a rule, begins to clone itself, attributing its copy to other files on all available media. Very soon, all files become infected. Such propagation is necessary to reduce the risk of being destroyed and increase the likelihood of further spread. This stage occurs very quickly and completely imperceptibly.
The further fate of this additional program depends on the purpose pursued by the person who created it. It is pointless to list a complete list of possibilities, because tasks can be very diverse. In general, you can specify the main areas that the virus can implement:
- computer malfunction: processor loading by endless calculations, which causes slowdowns, heating, failures; destruction of important system files, without which it is necessary to reinstall the operating system, etc .;
- initiation of sending network packets: the computer becomes part of the botnet;
- theft of personal data: access codes to some sites, bank accounts;
- distribution of emails of advertising nature.
After a reboot, the virus starts up on its own and starts its work. Obviously, these actions are undesirable for the user, therefore they are classified as malicious.
The above example examines file viruses. In addition to them, there are others with excellent distribution methods. So, recently there has been a real epidemic of viruses infecting computers through the autorun mechanism. In any case, the user whose computer is infected with the virus risks not only losing time on reinstalling all the programs, but also losing his own money, which the attacker can transfer to his accounts, knowing the codes and passwords for access.
To summarize, we will answer the question of what a virus is. This is the most common computer program that runs without the knowledge of the user and performs unwanted actions on the computer. To prevent infection, it is necessary to install special programs on the computer - antiviruses.