The term "computer virus" is used to refer to a specific category of programs, or elements of programs, capable of unauthorized entry into a computer for harm. It is especially worth noting the ability to self-replicate, which is characteristic of most of these programs.
Computer viruses act in the same way as their biological counterparts - they create copies of themselves in the system files of the computer before causing any obvious harm that allows them to be detected.
There is no single official classification system for computer viruses, but the type of exposure and methods of infection make it possible to divide them into:
- network worms that replicate themselves in the memory and hard disk of the infected computer. Worms do not have any additional malware, but they can slow down the system. Distributed over the network;
- Trojans (Trojan horses, Trojans), which are one of the most dangerous types of viruses. Trojans are programs hidden inside harmless applications, the launch of which leads to the initiation of the action of a malicious component - theft, modification or deletion of confidential user information, destruction of the computer system and other actions unauthorized by the owner;
- zombies, which are applications that allow remote control of an infected computer when connected to a network. A particular danger is the possibility of creating a network of zombie-infected computers for sending spam and spreading viruses;
- spyware that monitor and provide an attacker with access to confidential user data and, in turn, are subdivided into:
- phishing (phishing), which is a mailing list containing a link to a copy of a real financial institution, in order to obtain the user's personal information;
- pharming, which redirects to a fake page when trying to enter a web resource;
- malicious applications (malware), united by the task of destroying user files, changing the system registry and extracting personal information from the user.
It is especially worth highlighting mobile viruses designed to steal and use confidential user data for personal gain. Distributed in SMS and MMS messages.
