"Trojan horses" of the type of employees, all data of the program, go to the next and do the same thing "have properties to move through the communication network from one system to another, spreading a viral infection.
The virus is not found immediately: the first time Computer harbors infection, as to mask the virus is often used in combination with the "logic bomb" or "temporary bomb." The virus monitors throughout the processed information and can be moved using forward this information. Everything happens as if he was infected white blood cells and traveled with him on humans. Starting to act (to intercept management), gives the team a computer virus that infected a recorded version of the program. He then returns the program management. You do not notice because his computer is in a state of "healthy carrier of the virus." Detect the virus can only possess extremely advanced programming intuition because no violations in the mainframe at the moment are not themselves. But one day the computer "sick".
The experts collected files of letters from the blackmailer, demanding the transfer of large sums of money in one of the offices of the American firm PC Siborg "in the event of failure criminals threatening to bring computers down. According to the magazine "Business World", floppy-virusonositeli received ten thousand organizations using computers in their work.
To search for and identify intruders had set up special squads of British detectives.
All the viruses can be divided into two types, the discovery of which varies by difficulty: "vulgar virus" and "split virus." The "vulgarnogo virus," written by a single block, and when there is suspicion of infecting computer experts can find it at the very beginning of the epidemic (reproduction). The operation, however, very careful analysis of the entire operating system computers.
The "piecemeal virus" is divided into parts, at first glance, that do not respect. These parts contain the instructions that indicate the computer how to build them together to recreate and, therefore, reproduce the virus. Thus, it almost always is in the "distribution" state, only a short time their work gathering into a coherent whole. Typically, the creators of the virus show him the number of reproductions, after which he became aggressive.
Viruses can be introduced into the operating system, application or network driver.
Variations of viruses depend on the objectives pursued by their creator. Signs of them may be relatively benign, such as the slowdown in the performance of programs or the appearance of svetyascheysya point in the display (so called. "Italian poprygunchik"). Symptoms can be evolutionary, and the disease will worsen as they flow. So inexplicably programs are beginning to throng magnetic disks, resulting in a significantly increased level of program files. Finally, these acts can be devastating and lead to a blurring of the files and destroy software
What are ways the spread of computer viruses? They are based on the ability of the virus to use any transmitted data as a "means of transport." That is the beginning of infection is a risk that computers can create a large number of vehicles in the next day all the files and software to be infected. Thus, diskette or tape, transferred to other computers are able to infect them. Conversely, when "healthy" floppy disk introduced in the infected computer, it can become a carrier. Convenient for the dissemination of the epidemic has extensive telecommunications network. A single exposure to the personal computer has been infected or infected someone with whom contact. However, the most frequent method of infection - that copying programs, which is a common practice among users of personal computers. So are copied and infected program.
The experts caution against copying stolen programs. Sometimes, however, and formally delivered the program may be the source of infection. For example, the firm Aldus produced several thousands of infected diskettes with graphics programs.
Often, with the beginning of the epidemic linked computer name has been mentioned Robert Morris student Cornell University (USA), as a result of actions which have been infected critical computer networks east and west coasts of the United States. The epidemic spread to more than a thousand computers and 70 computer systems. The victims were, among other things, computer centers NASA Divermorskoy Laboratory of Nuclear Studies, Harvard, Pittsburgh, Maryland, Wisconsin, California, Stznfordskogo universities. Poignancy in the fact that the father of Robert Morris - a senior security department of the National Security Agency computers.
And the inventor of the virus is, however, very different people in August 1984, a student at the University of California, Fred Cohen, speaking at a conference, spoke about their experiences so that a friend of his called "computer virus". When the practical application of viruses is unknown, because banks, insurance companies, enterprises, to discover that their computers are infected with the virus, to prevent information about this prosochilis out.
The press often draw a parallel between computer viruses and virus "AIDS". Only orderly life with one or more partners the ability to protect against the virus. The indiscriminate connection with many computers will almost certainly lead to infection. Tortured, that wish to limit the use of untested software likely will remain practically unfeasible. This is because the original program for the "sterile" media faces a lot of money in convertible currency. Therefore, to avoid their uncontrolled copy almost impossible.
To be fair, that the spread of computer viruses has some advantages. In particular, they are, apparently, the best defense against hijackers software. Often, developers knowingly infect their floppies any innocuous virus, which is well detected by any antivirus test. This is a fairly reliable guarantee that no risk to copy a floppy disk