What is wrong with your computer, or Classification of viruses

Every computer owner knows: if the "true friend" stopped listening to commands, reacted to mouse clicks and began to "hang", then he "fell ill." A malicious program has been introduced into the computer system. Viruses, classification Which are very diverse, created exclusively for the destruction of computer systems. Once launched, the malicious program multiplies, destroying other applications and files.

Viruses penetrate into the computer in various ways. Sometimes they get into the system through infected media - disks or flash cards, but most often the system becomes infected with "pests" via the Internet or electronic messages. With the development of small local networks, network viruses appeared that destroy all computers connected by a grid.

Harmful programs are classified according to different signs. There is a classification of viruses in which they differ in "habitat". According to this system, viruses are divided into file, boot and file-boot. File varieties "eat" program files with extensions such as COM, EXE, BIN, SYS, BAT and others. Boot viruses settle in the boot sector of the disk and run with the OS. File-loading "pests" combine the properties of the two previous types.

Another classification of viruses sorts pests according to the type of launch. Non-resident views of this classification are run only once. Such "disposable pests" do not infect system memory and do not last long. Resident viruses, on the contrary, populate the main memory and infect the system after each launch.

Distinguish malicious programs and the method of disguise. This classification of viruses consists of masked and non-masked "pests". Nemaskiruyuschiesya viruses do not try to hide their harmful essence, and masked are also divided into species. Self-encrypting programs are automatically deciphered before launch. Invisible "stealth viruses" are well disguised - they can not be detected in a media program before launch. Mutating types are constantly changing, so they are most difficult to detect and "cure".

Most of the Ruses - only a part of any useful program. However, there are pests that are themselves made in the form of a useful program. Such software viruses are also of different types. Trojan programs, as a rule, take the form of an interesting game. After the launch, this game begins to gradually destroy the system. The Trojans do not know how to replicate and destroy other programs, but they are constantly working. Some, more advanced Trojans run themselves at any particular time. Programs-replicators, or "worms", live on the Web. To reproduce them, no other programs are required. "Worms", filled with viruses, creep across the Web and destroy all connected to it systems. Some viruses are created to destroy the products of certain programs, for example, Word or Exel documents.

No matter how extensive the classification of viruses, it is possible and necessary to combat pests. Anti-virus programs, such as Eset Nod32 and "Kaspersky Anti-Virus", deal with the prevention, diagnosis and treatment of PC-systems. They are especially necessary if the system is connected to the Internet all the time.