What are viruses: types, classification, characteristics, viral diseases, treatment and consequences. Types of viruses Types of viruses in a computer

Good afternoon Each of us has heard such a word as a computer virus. Some people know quite a lot about this concept, but for most readers, this word remains mysterious, incomprehensible, something far away.

What does computer virus mean? Let's first define a common virus. A virus is a kind of crystal that has its own DNA, cytoplasm and other elements. But the virus does not have its own nucleus, is not an independent organism and cannot exist outside of any living being, be it a cell or a multicellular organism.

Viruses can be in a dormant, incubating or active period. All this applies to computer viruses. Their essence is really the same. They also integrate into another organism, i.e. program, change its code, actively multiply, sometimes even damage the PC hardware. Also, like conventional viruses, computer viruses are quite diverse.

It can be said that a computer virus is a program that is able to create multiple duplicates of itself, integrate into the code of other software, into the system’s memory, it, and introduce its multiple duplicates in various ways.

The purpose of computer viruses is to disrupt the operation of various software systems, deleting many files, a failure in the structure of information, blocking the operation of various PC nodes in order to hinder their performance.

And this is true, just three days ago, my nephew came to me, I downloaded games to him via torrent. In the process of downloading, various shortcuts of various programs that I did not need began to appear on the monitor screen.

I then had to delete these softwares, but this is nonsense, the main thing is that a virus was introduced into it, which I ate removed. And then did it in safe mode PC operation "(This mode turns on only a part of the drivers and other programs, the most necessary, which makes it possible to search for a virus without disrupting the antivirus).

I advise you to use it, because. many viruses first of all try to disable the antivirus, which happened to my computer. It turns on quite easily, click on the hard reset button (next to the "Start" button), during the boot process you will be offered three options for turning it on, one of which is "Normal Mode" and "Safe".

I also want to give you advice, when you download through, always look at what you are downloading, how many files. Usually the file should be one if it is one program, not several. If there are several of them, this is already suspicious!

Also, keep an eye out for so-called files called "Silent installation" among the downloaded applications. If you see a similar file, immediately uncheck it. Otherwise, it is not clear what you will install!

And one more tip, if you use Kaspersky, it's better to choose KIS, because. it blocks such files quiet installation! Not worth saving at all good antivirus! But back to the types of viruses.

Types of computer viruses and their stages

Regarding the stages of the occurrence of the virus, it happens Latent, Incubatory and Active (The most dangerous!).

A) latent period- in this period, the virus is in the OS without active actions. A person may not notice it. Its capable of given state notice only, and then when it starts to scan the entire computer.

IN) Incubation period- unlike the previous one, a rather dangerous period. During this period, the virus software code activates and duplicates itself in many ways, distributing its duplicates not only to different parts of a particular PC, but also to the worldwide network.

Viruses are non-cellular infectious agents that have a genome (DNA and RNA), but are not gifted with a synthesizing apparatus. To reproduce, these microorganisms need cells of more highly organized organisms. Once in the cells, they begin to multiply, causing the development of various diseases. Each virus has a specific mechanism of action on its carrier. Sometimes a person does not even suspect that they are a virus carrier, since the virus does not harm health, this condition is known as latency, such as herpes.

To prevent viral diseases, it is important to maintain a healthy lifestyle, strengthening the body's defenses.

Origin and structure

There are several hypotheses for the origin of viruses. Science offers a version of the origin of viruses from fragments of RNA and DNA that were released from a large organism.

Coevolution suggests that viruses appeared simultaneously with living cells as a result of the construction of complex sets of nucleic acids and proteins.

Questions about how it reproduces and is transmitted are studied by a special section of microbiology - virology.

Each viral particle has genetic information (RNA or DNA) and a protein membrane (capsid) that acts as a defense.

Viruses come in a variety of shapes, ranging from simple helical to icosahedral. The standard value is approximately 1/100 of the size of an average bacterium. However, most viruses are very small, making them difficult to examine under a microscope.

Is living matter a virus?

There are two definitions of life forms of viruses. According to the first, extracellular agents are a collection of organic molecules. The second definition states that viruses are a special form of life. It is impossible to answer the question of what viruses exist, specifically and definitively, since biology assumes the constant emergence of new species. They are similar to living cells in that they have a special set of genes and evolve according to the way the natural set. They require a host cell to exist. The lack of their own metabolism makes it impossible to reproduce without outside help.

Modern science has developed a version according to which certain bacteriophages have their own immunity, capable of adapting. This is proof that viruses are a form of life.

Viral diseases - what is it?

Viruses of the plant world

If you ask yourself what viruses are, then, in addition to the human body, you can distinguish a special type of viruses that infect plants. They are not dangerous to humans or animals, since they can only reproduce in plant cells.

Artificial viruses

Artificial viruses are created to produce vaccines against infections. The list of artificially created viruses in the arsenal of medicine is not fully known. However, it is safe to say that the creation of an artificial virus can have a lot of consequences.

Such a virus is obtained by introducing into the cell an artificial gene that carries the information necessary for the formation of new types.

Viruses that infect the human body

What viruses are on the list of extracellular agents dangerous to humans and causing irreversible changes? Here is an aspect of the study of modern science.

The simplest viral disease is the common cold. But against the background of a weakened immune system, viruses can cause quite serious pathologies. Each pathogenic microorganism affects the organism of its host in a certain way. Some viruses can live in the human body for years and do no harm (latentness).

Certain latent species are even beneficial to humans, as their presence generates an immune response against bacterial pathogens. Some infections are chronic or lifelong, which is purely individual and due to the protective ability of the virus carrier.

Spread of viruses

Transmission of viral infections in humans is possible from person to person or from mother to baby. The rate of transmission or epidemiological status depends on the population density of the area, the weather and season, and the quality of medicine. It is possible to prevent the spread of viral pathologies if it is timely clarified which virus is currently detected in most patients, and appropriate preventive measures are taken.

Kinds

Viral diseases manifest themselves in completely different ways, which is associated with the type of extracellular agent that caused the disease, with the place of localization, with the rate of development of the pathology. Human viruses are classified as lethal and indolent. The latter are dangerous because the symptoms are unexpressed or weak, and it is not possible to quickly detect the problem. During this time, the pathogenic organism can multiply and cause serious complications.

Below is a list of the main types of human viruses. It allows you to clarify which viruses are there and which pathogenic microorganisms cause diseases that are dangerous to health:

1. Orthomyxoviruses. This includes all types of influenza viruses. To find out which influenza virus caused the pathological condition, special tests will help.
2. adenoviruses and rhinoviruses. They affect the respiratory system, cause SARS. Symptoms of the disease are similar to flu, can cause such serious complications as pneumonia, bronchitis.
3. Herpesviruses. Activated against the background of reduced immunity.
4. Meningitis. Pathology is caused by meningococci. The mucous membrane of the brain is affected, the nutrient substrate for the pathogenic organism is the cerebrospinal fluid.
5. Encephalitis. It has a negative effect on the membrane of the brain, causing irreversible changes in the central nervous system.
6. Parvovirus. The diseases caused by this virus are very dangerous. The patient has convulsions, inflammation of the spinal cord, paralysis.
7. Picornaviruses. Cause hepatitis.
8. Orthomyxoviruses. Provoke mumps, measles, parainfluenza.
9. Rotavirus. The extracellular agent causes enteritis, intestinal flu, gastroenteritis.
10. rhabdoviruses. They are causative agents of rabies.
11. Papoviruses. Cause papillomatosis in humans.

Retroviruses. They are the causative agents of HIV, and after AIDS.

life-threatening viruses

Some viral diseases are quite rare, but they pose a serious danger to human life:

1. Tularemia. The disease is caused by the Francisellatularensis bacillus. The clinical picture of the pathology resembles the plague. It enters the body by airborne droplets or by a mosquito bite. Transmitted from person to person.
2. Cholera. The disease is fixed very rarely. Vibrio cholerae virus enters the body through the use of contaminated water, contaminated food.
3. Creutzfeldt-Jakob disease. In most cases, the patient has a lethal outcome. It is transmitted through contaminated animal meat. The causative agent is a prion - a special protein that destroys cells. Manifested by a mental disorder, severe irritation, dementia.

It is possible to determine which type of virus caused the disease by conducting laboratory tests. An important argument is the epidemic state of the region. It is also important to find out which virus is currently circulating.

Signs of viral infections and possible complications

The main part of the viruses provokes the occurrence of acute respiratory diseases. The following manifestations of SARS are distinguished:

• development of rhinitis, cough with clear mucus;
• an increase in temperature to 37.5 degrees or fever;
• feeling of weakness, headaches, decreased appetite, muscle pain.

Late treatment can cause serious complications:

• adenovirus can cause inflammation of the pancreas, which leads to the development of diabetes;
• beta-hemolytic streptococcus, which is the causative agent of tonsillitis and other types of inflammatory diseases, with reduced immunity can provoke diseases of the heart, joints, epidermis;
• influenza and SARS are often complicated by pneumonia in children, elderly patients, pregnant women.

Viral pathologies can also cause other serious complications - sinusitis, joint damage, heart pathology, chronic fatigue syndrome.

Diagnostics

Experts determine a viral infection by common symptoms, based on which virus is currently circulating. Virological studies are used to determine the type of virus. Modern medicine widely uses methods of immunodiagnostics, including immunoindication, serodiagnostics. Which ones to pass the specialist decides on the basis of a visual examination and the collected anamnesis.

Appoint:

• enzyme immunoassay;
• radioisotope immunoassay;
• study of hemagglutination inhibition response;
• immunofluorescence reaction.

Treatment of viral diseases

The course of treatment is chosen depending on the pathogen, specifying which types of viruses caused the pathology.

For the treatment of viral diseases are used:

1. Drugs that stimulate the immune system.
2. Medicines that destroy a specific type of virus. The diagnosis of a viral infection is necessary, since it is important to clarify which virus responds best to the selected drug, which makes it possible to make therapeutic therapy more targeted.
3. Medicines that increase the sensitivity of cells to interferon.

For the treatment of common viral diseases, apply:

1. "Acyclovir". Assign for herpes, it eliminates the pathology completely.
2. Relezan, Ingavirin, Tamiflu. Assign for different types of influenza.
3. Interferons together with Ribavirin are used to treat hepatitis B. A new generation drug, Simeprevir, is used to treat hepatitis C.

Prevention

Preventive measures are selected depending on the type of virus.

Preventive measures are divided into two main areas:

1. Specific. They are carried out with the aim of developing specific immunity in humans through vaccination.
2. Nonspecific. Actions should be aimed at strengthening the body's defense system, by providing small physical exertion, a properly composed diet and personal hygiene.

Viruses are living organisms that are almost impossible to avoid. To prevent serious viral pathologies, it is necessary to vaccinate according to the schedule, lead a healthy lifestyle, and organize a balanced diet.

Department of Education of the Ordzhonikidzevsky District Administration

Computer viruses

Informatics essay

Executor:

Novikov Alexander

9 "B" class

Supervisor:

Nazimova Elena Anatolievna

IT-teacher

Yekaterinburg 1999

What is a computer virus?

A computer virus is a specially written small program that can "attribute" itself to other programs, as well as perform various unwanted actions on a computer. A program that contains a virus is called "infected". When such a program starts, the virus first takes control. The virus finds and "infects" other programs, and also performs some harmful actions (for example, it corrupts files or the file allocation table on the disk, "contaminates" RAM, etc.). A virus is a program that has the ability to reproduce itself. This ability is the only property common to all types of viruses. A virus cannot exist in "complete isolation". This means that today it is impossible to imagine a virus that would not somehow use the code of other programs, information about the file structure, or even just the names of other programs. The reason for this is quite clear: the virus must, in some way, provide

handover of control.

Main types of computer viruses

There is a completely formal system that allows you to classify computer viruses and name them in such a way as to avoid the situation when the same virus has unrecognizably different names in the classification of different antivirus software developers. Despite this, it is still impossible to say about the complete unification of the names and characteristics of viruses. To a large extent, this is determined by the fact that by the time some “rules of the game” were formulated, anti-virus tools already existed that worked in their own notation. General unification would require considerable effort and modification of programs and documentation. In a number of cases this has been done. We will proceed from the fact that an ordinary user does not need to delve into all the subtleties of the functioning of a virus: objects of attack, methods of infection, features of manifestation, etc. But it is desirable to know what viruses are, to understand the general scheme of their work.

Among the variety of viruses, the following main groups can be distinguished:

– boot viruses; this is the name of viruses that infect the boot sectors of floppy disks and hard drives;

– file viruses; in the simplest case, such viruses infect executable files; if everything is more or less clear with boot viruses, then file viruses are a much less definite concept; it suffices, for example, to say that a file virus may not modify a file at all (satellite viruses and viruses of the Dir-II family);

– boot-file viruses; such viruses have the ability to infect both boot sector code and file code. There are not very many such viruses, but among them there are extremely vicious specimens (for example, the well-known OneHalf virus).

Viruses written in the so-called. macrolanguages, are formally file-based, but they infect not executable files, but data files, however, arranged in such a way that they can be infected - this is already on the conscience of software publishers.

Corrupted and infected files

A computer virus can ruin, i.e. change properly, any file on the disks available on the computer. But the virus can infect some types of files. This means that a virus can "infiltrate" these files, i.e. modify them so that they contain a virus that, under certain circumstances, can start working.

It should be noted that program texts and documents, database information files, spreadsheet tables and other similar files cannot be infected by a virus, it can only spoil them.

The virus can infect the following types of files:

1. Executable files, those. files with extensions .COM and .EXE, as well as overlay files loaded when other programs are running. The virus in infected executable files starts its work at the start of the program in which it is located. The most dangerous are those file viruses that, after being launched, remain resident in memory - they can infect files and harm until the next reboot of the computer. And if they infect any program launched from the AUTOEXEC.BAT or CONFIG.SYS file, then the virus will start working again when you reboot from the hard disk.

2. Operating system loader and main boot

hard disk recording. These areas infect the boot virus.

Such a virus starts its work at the initial boot of the computer and becomes resident, i.e. resides permanently in the computer's memory. The distribution mechanism is the infection of boot records inserted into the computer diskettes. Often such viruses consist of two parts, because the boot record and the master boot record are small and it is difficult to place the entire virus program in them. Part of the virus that does not fit in them is located in another part of the disk, for example, at the end of the root directory of the disk or in a cluster in the data area of ​​the disk (usually such a cluster is declared defective so that the virus program is not overwritten when data is written to the disk).

3. Device drivers, those. files specified in the Device application of the CONFIG.SYS file. The virus in them starts its work every time the corresponding device is accessed. Viruses that infect device drivers are very rare because drivers are rarely copied from one computer to another. The same applies to DOS system files - their infection is also theoretically possible, but it is ineffective for distribution.

As a rule, each specific type of virus can infect only one or two types of files. Most often there are viruses that infect executable files. Some viruses only infect .COM files, some only infect .EXE files, and most infect both. In second place in terms of prevalence are boot viruses. Some viruses infect both files and disk boot areas. Viruses that infect device drivers are extremely rare, usually such viruses can also infect executable files.

Viruses that change the file system

Recently, a new type of virus has become widespread - viruses that change the file system on the disk. These viruses are commonly referred to as Dir. Such viruses hide their body in some part of the disk (usually in the last disk cluster) and mark it in the file allocation table (FAT) as the end of the file. For all .COM and .EXE files, the pointers to the first section of the file contained in the corresponding directory entries are replaced by a link to the disk section containing the virus, and the correct pointer in encoded form is hidden in the unused part of the directory entry. Therefore, when any program is launched, a virus is loaded into memory, after which it remains resident in memory, connects to DOS programs to process files on the disk and

for all references to the elements of the catalog, it produces the correct links.

Thus, when the virus is running, the file system on the disk seems completely normal. Nothing strange is observed during a superficial examination of an infected disk on a "clean" computer. Unless, when trying to read or copy program files from an infected floppy disk, only 512 or 1024 bytes will be read or copied into them, even if the file is much longer. And when you run any executable program from a disk infected with such a virus, this disk, as if by magic, begins to appear healthy (no wonder, because the computer becomes infected in this case).

When analyzed on a "clean" computer using the ChkDsk or NDD programs, the file system of a disk infected with a Dir virus seems to be completely corrupted. So, the ChkDsk program gives a bunch of messages about file intersections ("...cross linked on cluster...") and about chains of lost clusters ("... lost clusters found in ... chains"). You should not correct these errors with ChkDsk or NDD programs - in this case, the disk will be hopelessly damaged. To fix disks infected with these viruses, you should use only special anti-virus programs (for example, the latest versions of Aidstest).

"Invisible" and

self-modifying viruses

To prevent their detection, some viruses use rather cunning camouflage techniques. We will talk about two of them: "invisible" and self-modifying viruses.

"Invisible" viruses. Many resident viruses (both file and boot) prevent their detection by intercepting DOS (and thus application programs) calls to infected files and disk areas and releasing them in their original (uninfected) form. Of course, this effect is observed only on an infected computer - on a "clean" computer, changes in files and disk boot areas can be easily detected.

Note that some anti-virus programs can detect "invisible" viruses even on an infected computer. For example, the ADinf program from Dialog-Science performs disk reading without using DOS services, and the AVSP program from Dialog-MGU “disconnects” for a while

virus checks (the latter method does not always work).

Some anti-virus programs use the ability of "invisible" file viruses to "cure" infected files to fight viruses. They read (when the virus is running) information from infected files and write them to disk in a file or files, where this information is stored in an undistorted form. Then, after booting from a "clean" floppy, the executable files are restored in their original form.

Self-modifying viruses. Another way that viruses use to hide from detection is to modify their body. Many viruses store most of their bodies in code so that disassemblers can't figure out how they work. Self-modifying viruses use this technique and often change the parameters of this encoding, and in addition, they also change their start part, which serves to decode the remaining commands of the virus. Thus, in the body of such a virus there is not a single permanent string of bytes by which the virus could be identified. This, of course, makes it difficult for detection programs to find such viruses.

However, detection programs still learned to catch "simple" self-modifying viruses. In these viruses, variations of the mechanism for decrypting the encoded part of the virus concern only the use of certain computer registers, encryption constants, the addition of "insignificant" commands, etc. And the detection programs have adapted to detect commands in the starting part of the virus, despite the masking changes in them. But recently, viruses with extremely complex self-modification mechanisms have appeared. In them, the initial part of the virus is generated automatically according to very complex algorithms: each meaningful decryptor instruction is transmitted by one of hundreds of thousands of possible options, while more than half of all Intel-8088 commands are used. The problem of recognizing such viruses is quite complicated, and has not yet received a completely reliable solution. However, some anti-virus programs have tools for finding such viruses, and Dr. Web - as well as heuristic methods for detecting "suspicious" sections of program code, typical of self-modifying viruses.

Basic methods of protection against computer viruses

To protect against viruses, you can use:

- general information protection tools, which are also useful as insurance against physical damage to disks, misbehaving programs or erroneous user actions;

– preventive measures to reduce the likelihood of infection with the virus;

specialized programs for protection against viruses.

General information security tools are useful for more than just protecting against a virus. There are two main types of these funds:

copying information – creation of copies of files and system areas of disks;

access control prevents unauthorized use of information, in particular, protection against changes to programs and data by viruses, malfunctioning programs and erroneous actions of users.

Despite the fact that general information protection tools are very important for protecting against viruses, they are still not enough. It is also necessary to use specialized programs to protect against viruses. These programs can be divided into several types: detectors, doctors (phages), auditors (programs for monitoring changes in files and system areas of disks), auditor doctors, filters (resident programs for protecting against viruses) and vaccines (immunizers). We give a brief definition of these concepts, and then consider them in detail.

Programs-detectors allow you to detect files infected with one of several known viruses.

Doctor Programs , or phages , “cure” infected programs or disks by “biting out” the body of the virus from infected programs, i.e. restoring the program to the state it was in before the virus infection.

Auditor programs First, information about the state of programs and system areas of disks is stored, and then their state is compared with the original one. If inconsistencies are found, the user is informed about this.

Doctors-auditors - these are hybrids of auditors and doctors, i.e. programs that not only detect changes in files and system areas of disks, but can also automatically return them to their original state in case of changes.

Filter programs are located resident in the computer's RAM and intercept those calls to the operating system that are used by viruses to multiply and cause harm, and report them to the user.

vaccine programs, or immunizers , modify programs and disks in such a way that this does not affect the operation of programs, but the virus against which vaccination is performed considers these programs or disks already infected. These programs are highly inefficient and are not considered further.

Programs-detectors and doctors

In most cases, you can find already developed detection programs to detect a virus that has infected your computer. These programs check to see if the files on the drive specified by the user contain a combination of bytes specific to a given virus. When it is found in any file, a corresponding message is displayed on the screen. Many detectors have modes for curing or destroying infected files.

It should be emphasized that detector programs can only detect viruses that are "known" to it. The Scan program from McAfee Associates and D.N. Lozinsky's Aidstest can detect about 1000 viruses, but there are more than five thousand in total! Some detector programs, such as Norton AntiVirus or Dialog-MGU's AVSP, can be configured for new types of viruses; they only need to specify the byte combinations inherent in these viruses. However, it is impossible to develop such a program that could detect any previously unknown virus.

Thus, from the fact that a program is not recognized by detectors as infected, it does not follow that it is healthy - it may contain some new virus or a slightly modified version of an old virus that is unknown to detector programs.

Auditor programs

Program-auditors have two stages of work. First, they store information about the state of programs and system areas of disks (the boot sector and the sector with the hard disk partition table). It is assumed that at this moment programs and system areas of the disks are not infected. After that, using the auditor program, you can at any time compare the state of programs and system areas of disks with the original. About identified

inconsistencies are reported to the user.

Many users include the command to run the audit program in the batch file AUTOEXEC.BAT so that the status of programs and disks is checked every time the operating system is loaded. This allows you to detect a computer virus infection when it has not yet had time to do much harm. Moreover, the same auditor program will be able to find files damaged by the virus.

Filter programs

One of the reasons why such a phenomenon as a computer virus became possible is the lack of effective means in the MS DOS operating system to protect information from unauthorized access. Due to the lack of protection tools, computer viruses can change programs imperceptibly and with impunity, corrupt file allocation tables, and so on.

In this regard, various companies and programmers have developed filter programs, or resident programs for protecting against viruses, which to a certain extent make up for this shortcoming of DOS. These programs are located resident in the computer's RAM and "intercept" those calls to the operating system that are used by viruses to reproduce and cause harm. Such "suspicious" actions are, in particular, changing .COM and .EXE files, removing the "read-only" attribute from the file, writing directly to the disk (writing to an absolute address), formatting the disk, setting a "resident" (permanently located in RAM) programs.

Each time a non-'suspicious' action is requested, a message is displayed on the computer screen stating what action is requested and what program wants to perform it. You can either allow this action or disable it (Fig. 1).

Some filter programs do not "catch" suspicious actions, but check the programs called for execution for viruses. This, of course, slows down the computer.

The degree of protection provided by filter programs should not be overestimated, since many viruses, in order to reproduce and cause harm, access operating system programs directly, without using the standard method of calling these programs through interrupts, and resident programs intercept only these interrupts to protect against viruses. In addition, filter programs do not help against infection of the hard drive with viruses that spread through the boot sector, since such infection occurs during DOS boot, i.e. before starting any programs or installing drivers.

However, the advantages of using filter programs are very significant - they allow you to detect many viruses at a very early stage, when the virus has not yet had time to multiply and spoil something. In this way, losses from the virus can be minimized.

What they can and cannot

computer viruses

Due to ignorance of the mechanism of computer viruses, as well as under the influence of various rumors and incompetent publications in the press, a peculiar complex of fear of viruses is often created, the so-called. "virusophobia". This complex has two manifestations.

1. The tendency to attribute any data corruption or unusual occurrence on a computer to viruses. For example, a floppy disk is not formatted; for a “virusophobe”, this is not a possible defect in a floppy disk or disk drive, but the action of a virus. If a bad block appears on the hard drive, then, of course, the virus is also to blame. In fact, unusual computer phenomena are more often caused by user errors, software errors, or hardware defects.

2. Exaggerated ideas about the capabilities of viruses. Some people think, for example, that it is enough to insert an infected floppy disk into the drive for the computer to become infected with a virus. It is also widely believed that for computers connected

into a network, or even just standing in the same room, the infection of one computer will necessarily immediately lead to the infection of the rest.

The best cure for virusophobia is knowing how viruses work, what they can and cannot do. Viruses are ordinary programs and cannot perform any supernatural actions.

In order for a computer to become infected with a virus, a program containing the virus must be executed on it at least once. Therefore, the primary infection of a computer with a virus can occur in one of the following cases:

– an infected program of the .COM or .EXE type or an infected overlay program module was executed on the computer;

– the computer was booted from a floppy disk containing an infected boot sector;

an infected operating system or an infected device driver was installed on the computer;

It follows that there is no reason to be afraid of a computer being infected with a virus if:

texts of programs, documents, information files of databases or spreadsheets, etc. are copied to the computer. These files are not programs and therefore cannot be infected with a virus;

on an uninfected computer, files are copied from one floppy disk to another. If the computer is "healthy", then neither it nor the copied floppy disks will be infected with a virus. The only way to transmit the virus in this situation is to copy the infected file: in this case, its copy, of course, will also be “infected”, but neither the computer nor any other files will be infected;

using word processors, spreadsheets, database management systems and other programs available on the hard disk of an uninfected computer, information files contained on diskettes are processed.

Actions in the event of a virus infection

When a computer becomes infected with a virus (or if it is suspected), it is important to follow four rules.

First of all, do not rush and make rash decisions - ill-conceived actions can lead not only to the loss of some files that could be recovered, but also to re-infection of the computer.

2. One action must be performed immediately - you must turn off the computer so that the virus does not continue its destructive actions.

3. All actions to detect the type of infection and disinfect the computer should be performed only when the computer is booted from a write-protected "reference" floppy disk with the operating system. In this case, you should use only programs (executable files) stored on write-protected diskettes. Failure to comply with this rule can lead to very serious consequences, since when loading DOS or running a program from an infected disk, a virus can be activated in the computer, and if the virus is running, it will be pointless to disinfect the computer, because. it will be accompanied by further infection of disks and programs.

4. If a resident filter program is used to protect against a virus, then the presence of a virus in any program can be detected at a very early stage, when the virus has not yet managed to infect other programs and corrupt any files. In this case, you should reload DOS from the floppy and delete the infected program, and then rewrite this program from the reference floppy or restore it from the archive. In order to find out if the virus has corrupted some other files, you should run an auditor program to check for changes in files, preferably with a wide list of files to be scanned. In order not to continue infecting the computer during the scan, you should run the executable file of the auditor program located on the diskette.

Computer treatment. In the case when the virus has already managed to infect or corrupt some files on the computer's disks, you must perform the following steps.

Reboot the DOS operating system with a pre-prepared reference floppy disk. This floppy disk, like other floppy disks used in the aftermath of a computer virus infection, must be labeled with a write-protect label to prevent viruses from infecting or corrupting the files on these disks. Note that the reboot should not be performed using the keyboard shortcut Ctrl+Alt+Del, because some viruses manage to "survive" such a reboot.

If the computer has a program for setting the configuration (it is called when you press a certain key combination during the initial boot of the computer), then you should run this program and check whether the computer configuration parameters are set correctly, because. they can be damaged by a virus. If they are installed incorrectly, then they must be reinstalled.

If there are detector programs to detect the virus that infects the computer, you should run these programs to check the computer's disks. To find desired program, you can run the existing detector programs one by one to check the infected disk (in this case, it is better not to use those detector program modes in which they cure or delete infected files without confirmation). First, it makes sense to run programs that detect several viruses at once, such as Scan or Aidstest. If any of the detector programs report that it has found a virus, then it must be used in the process of eliminating the consequences of a computer infection with a virus, as described below. It should be noted, however, that very often computers are infected with several viruses at once, therefore, having discovered one virus, one should not calm down, a second or third virus may be in the computer.

Next, you should sequentially neutralize all disks that could be infected with a virus, as described below. Note that if the hard disk in the computer is divided into several logical disks, then when booting from a floppy disk, only one logical disk can be available - the one from which the DOS operating system is loaded. In this case, you should first disable the logical drive from which DOS boots, and then boot from the hard drive and disable other logical drives.

Disc treatment. If the drive has archived copies of all the files you need, it's easiest to reformat the drive and then restore all the files on that drive using the archived copies. Suppose now that the disk contains the necessary files, copies of which are not in the archive. For definiteness, we will assume that this disk is on the disk drive (B:). You need to do the following.

Run a detector program for the disk that detects the virus that the computer is being infected with (if it is not clear which detector detects the virus, you should run the detector programs in turn until one of them detects the virus). In this case, it is better not to establish a treatment regimen.

If the detection program has detected a bootable virus, you can safely use its treatment mode to eliminate the virus. If a virus of the Dir type is detected, it must also be removed using one or another anti-virus program, in no case using programs like NDD and ChkDsk for this.

Now that you know that there are no Dir-type viruses on the disk, you can check the integrity file system and surfaces

disk using the program NDD: NDD B: C. If the damage to the file system is significant, then it is advisable to copy all the necessary files from the disk, copies of which are not in the archive, to floppy disks and re-format the disk. If the disk has a complex file structure, then you can try to correct it using the DiskEdit program from the Norton Utilites kit.

If information about the files on the disk for the auditor program has been preserved, then it is useful to run the auditor program to diagnose changes in the files. This will determine which files have been infected or corrupted by the virus. If the auditor program also performs the function of a doctor, you can entrust it with the restoration of damaged files.

Delete everything from disk junk files, as well as files, copies of which are in the archive. Those files that have not been modified by the virus (this can be installed using the auditor program) do not need to be deleted.

Under no circumstances should .COM and .EXE files be left on the disk, for which the audit program reports that they have been changed. Those .COM and .EXE files that are not known to have been modified by a virus or not should be left on the disk only when absolutely necessary.

If the disk you are working on is a system disk (that is, it can boot the DOS operating system), then the boot sector and operating system files should be written to it again. This can be done with the SYS command.

If the computer has become infected with a file virus and you have not treated it with the help of a doctor-auditor, you should run a doctor program to disinfect this disk. Infected files that the doctor could not recover should be destroyed. Of course, if

Similar abstracts.

Computer virus- this is a specially written, small-sized program (i.e., some set of executable code) that can "attribute" itself to other programs ("infect" them), create copies of itself and embed them in files, computer system areas, etc. .d., as well as perform various unwanted actions on the computer.

There are network viruses - self-replicating and spreading malicious software products online. They can affect both network and system information, as well as user information.

Computer viruses owe their name to a certain similarity with "biological" viruses in:

The ability to self-reproduce;

High propagation speed;

Selectivity of affected systems (each virus infects only certain systems or homogeneous groups of systems);

The ability to "infect" still uninfected systems;

Difficulties in fighting viruses, etc.

The most famous case of mass infection of Internet computers, which entailed serious consequences, is an emergency on November 2, 1988, when thousands of computers were practically disabled as a result of the spread of the Morris virus ("worm", WORM), which was a complex 60-kilobyte program written in C language. The program ran on several different, albeit similar, operating systems: BSD-Unix, VAX, SunOS. "Settled" on one computer, the virus tried to infect all other PCs connected to this one. First, he tried to find the next victim by trying to establish a connection with Telnet services, or SMTP, or Rexec. If a computer was detected on the other end of the connection, the virus tried to infect it in one of three ways. In the case of a trusting relationship between an already infected computer and a new victim, infection occurred using standard Bourne shell commands rch. In the absence of such relationships, infection occurred using the fingerd or sendmail utilities. For infection using the fingerd utility, 536 bytes of data were written to the input buffer of this utility. When the buffer overflowed, the return code from the utility turned out to be equal to the instruction to execute the virus code. For infection using the sendmail command, the debug option of this command was used, intended for debugging. With its help, commands were entered into the victim computer, leading to the copying of the virus on the PC. After penetrating the victim computer, the virus found the Unix password file and tried to guess the passwords of privileged users of the computer. The virus had several password splitting algorithms. One of them tried to guess a password using various derivatives of usernames, another had a built-in table of 432 most commonly used passwords, and a third guessed a password by brute force. To speed up the process of splitting passwords, the virus launched several parallel processes. Having received the passwords of all users, the virus tried to use them to capture the following computers. In the short time of its existence (no more than a day), the virus multiplied indefinitely and paralyzed most of the large US computer complexes connected to the Internet with its work.

On October 16, 1999, a message appeared on the Internet about an attack on the SPAN network of VAX / VMS systems by a W.COM network worm. This virus only infects DEC VMS operating systems and spreads over networks using DECnet family protocols. TCP/IP networks were not exposed to the threat of infection, but could serve as a transport medium for the spread of the virus if encapsulated DECnet packets were transmitted over TCP/IP networks.

The W.COM worm modified executable files by adding its own code to them, which resulted in the issuance of threats to developers of nuclear weapons on the screen. To propagate, the worm searched the network for users without a password or with a password that matched the username. When such a user was found, the worm ran on behalf of that user and modified new files. The worst consequences were when the worm was executed on behalf of a privileged user. In this case, it created new users and modified the passwords of existing users, i.e., created conditions for its initialization in the future. Penetration into other systems was carried out by random enumeration of network addresses and access on behalf of active users to remote systems.

Often viruses on the Internet disguise themselves as zip or otherwise compressed files. The case of 1995 is indicative, when it was possible to write off pkz300B.exe or pkz300B.zip files. When they were launched or unzipped, self-extracting archives were activated, causing the hard drive to be reformatted.

In 1999, the emergence of a macro virus that steals the keys of the PGP encryption system was noted. It belongs to a class that some experts call spyware. These viruses are designed to steal information stored in other people's computers. Caligula gets on a PC along with an infected document in the format Microsoft Word. Once on a new PC, this macro virus checks to see if a copy of the PGP software is installed on it. If such a system is successfully discovered, the secret keys to the ciphers used in it - the most important component in terms of the security of data encrypted using the PGP algorithm - will be copied to one of the FTP servers on the Internet.

The Soubig virus can be translated from English as "so big", it first declared itself on August 18, 2003. Soubig is a new generation of superviruses and is dangerous because it has an incredible ability to spread and reproduce itself. Especially dangerous is his version of Soubig - Ef. The purpose of the virus is to infect email. Its peculiarity is that it can change the content of the texts of e-mails and attack through e-mail every separate computer hundreds of different messages.

In 2005, one of the active viruses was the W32.Codbot.AL worm. This virus spreads by exploiting known vulnerabilities in processes SQL Server LSASS and RPC-DCOM. For its installation on a computer, it registers itself as system process, which is run every time the system starts. While running, it connects to various IRC servers and waits for commands. The virus can receive all kinds of commands, such as gathering information about the computer, recording keystrokes, activating FTP services, and even downloading and running other malware.

The second worm, W32.Semapi.A, spreads via e-mail in a message with different headers, sender, and other properties, as an attachment with a different name and extension. When a worm is installed on a computer, it copies several files to HDD and creates a series of entries in the registry to ensure that it starts every time the computer is turned on. Then he searches email addresses in all files with certain extensions on the affected computer and sends copies of itself to them.

The Trojan Banker.XP attempts to obtain sensitive data such as access passwords various services on the infected computer. Upon receipt, it compiles them and sends them to the hacker.

In June 2005, Kaspersky Lab announced that it had registered the first malware that infects known system automation "1C: Enterprise". This virus was named Tanga.

Tanga is distributed in the "1C: Enterprise 7.7" system by infecting user files responsible for external reports and having the "ERT" extension. The method of placing Tanga in infected files largely corresponds to macro viruses that infect documents and tables of the package. Microsoft programs office. Malicious modules are located in a special data block and are activated when a report file is opened. To work, the virus uses a special library "Compound.dll". If given file missing from the system, the virus will not run.

It should be noted that the author of this version of Tanga showed an understanding of the complexity of the work of anti-virus experts and did everything to minimize the time of code analysis and the damage from its possible distribution. To do this, the creator of the virus deprived it of any destructive functions, making the program safe even in the event of infection.

Computer viruses can be classified according to the following criteria:

- according to the habitat of the virus:

network;

file;

loading;

- according to the method of infection:

resident;

· non-resident;

− according to destructive possibilities:

harmless;

· non-hazardous;

· dangerous;

very dangerous;

- according to the features of the virus algorithm.

Full text search:

Home > Test work >Informatics

Ministry of Education and Science of the Russian Federation

Russian Trade and Economic University

Kazan Institute (branch)

Department of Mathematics and Higher Mathematics

Test No. 1

discipline: "Informatics"

COMPUTER VIRUSES

Performed:

1st year student

departments of special faculty

"Finance and credit" group

Checked:

Kazan, 2007

PLAN

Introduction

Essence and manifestation of computer viruses

The main types and types of computer viruses

How do viruses spread?

Detection of computer viruses

5. Preventive measures against viruses

Conclusion

Bibliography

Introduction

Computer virus- a specially created program designed to perform certain actions that interfere with working on a computer. Many programs - viruses are harmless, but unfortunately not all are completely harmless. First, they take up space in random access memory and on disk. Secondly, they may contain errors, which can lead to system crashes and reboots. Therefore, if the virus is fairly harmless, then you should still get rid of it.

Currently, there are several types and types of viruses. The main types of computer viruses are: software, boot viruses and macro viruses. Over 5,000 species are currently known. software viruses, they can be classified according to the following features: habitat; method of contamination of the habitat; impact; features of the algorithm.

The main ways in which viruses enter a computer are removable drives(flexible and laser), as well as computer networks. Hard disk infection with viruses can occur when the computer is booted from a floppy disk containing a virus. Such an infection can also be accidental, for example, if the floppy disk is not removed from drive A: and the computer is restarted, while the floppy disk may not be a system disk. It is much easier to infect a floppy disk. A virus can get on it even if the floppy disk is simply inserted into the disk drive of an infected computer and, for example, its table of contents is read. But the most common way for viruses to spread is through a network of computers, and in particular the Internet, when other programs, such as games, are rewritten and launched. There may be other, quite rare cases, when another hard drive that has been infected is inserted into the computer. To avoid this, boot from the system floppy and either check the hard drive with special anti-virus programs, or, better, partition and format the drive with Fdisk and Format.

To detect viruses, there are special anti-virus programs that allow you to detect and destroy viruses. There is a fairly wide selection of antivirus programs. These are Aidstest (Lozinsky), Dr Web, Norton antivirus for Windows, DSAV kit and others.

Essence and manifestation of computer viruses

The mass use of personal computers, unfortunately, turned out to be associated with the emergence of self-reproducing virus programs that prevent the normal operation of the computer, destroy the file structure of disks and damage the information stored in the computer. Having penetrated into one computer, a computer virus is able to spread to other computers.

The reasons for the appearance and spread of computer viruses, on the one hand, are hidden in the psychology of the human personality and its shadow sides (envy, revenge, vanity of unrecognized creators), on the other hand, due to the lack of hardware protection and counteraction from operating system personal computer.

Despite the laws adopted in many countries to combat computer crimes and the development of special software to protect against viruses, the number of new software viruses is constantly growing. This requires the user of a personal computer to be knowledgeable about the nature of viruses, how to infect and protect against viruses.

The main ways for viruses to enter a computer are removable disks (floppy and laser), as well as computer networks. Hard disk infection with viruses can occur when the computer is booted from a floppy disk containing a virus. Such an infection can also be accidental, for example, if the floppy disk is not removed from drive A: and the computer is restarted, while the floppy disk may not be a system disk. It is much easier to infect a floppy disk. A virus can get on it even if the floppy disk is simply inserted into the disk drive of an infected computer and, for example, its table of contents is read.

When a computer becomes infected with a virus, it is very important to detect it in a timely manner. To do this, you should know about the main signs of the manifestation of viruses. They can include:

termination of work or incorrect operation of previously successfully functioning programs;

slow computer performance

inability to boot the operating system;

disappearance of files and directories or distortion of their contents;

changing the date and time of file modification;

resizing files;

unexpected significant increase in the number of files on the disk;

a significant reduction in the size of free RAM;

displaying unexpected messages or images on the screen4

submission of unforeseen sound signals;

frequent freezes and computer crashes.

However, by all these signs it is impossible to say with certainty that a virus has wound up in the computer. Since there may be other malfunctions caused by malfunctions or malfunctions of the system. For example, in a purchased computer, when it starts, instead of Russian characters, strange characters are displayed that you see for the first time. The reason for this may be that the Cyrillic driver for the display is not installed. The same reason - the lack of a driver for the printer - can also explain the strange behavior of the printer. System failures can be caused by a bad chip inside the system unit or in the cord connection.

The main types and types of computer viruses

The main types of computer viruses are:

software viruses;

boot viruses;

macro viruses.

Computer viruses are also related to the so-called Trojan

horses (Trojans, Trojans).

Software viruses.

Software viruses are blocks of code that are purposefully embedded inside other application programs. When a program carrying a virus is launched, the virus code implanted in it is launched.

The operation of this code causes changes hidden from the user in the file system of hard drives and / or in the content of other programs. So, for example, a virus code can reproduce itself in the body of other programs - this process is called reproduction. After a certain time, having created a sufficient number of copies, a software virus can proceed to destructive actions: disrupting the operation of programs and the operating system, deleting information stored on the hard drive. This process is called virus attack.

The most destructive viruses can initiate formatting hard drives. Since disk formatting is a rather lengthy process that should not go unnoticed by the user, in many cases software viruses are limited to multiplying data only in the system sectors of the hard disk, which is equivalent to losing file system tables. In this case, the data on the hard disk remains intact, but it is impossible to use it without the use of special tools, since it is not known which sectors of the disk belong to which files. Theoretically, it is possible to recover data in this case, but the complexity of this work can be extremely high.

It is believed that no virus is able to disable computer hardware. However, there are times when hardware and software are so intertwined that software corruption must be repaired by replacing the hardware. So, for example, in most modern motherboards base system input/output (BIOS) is stored in writable read-only storage devices (so-called flash memory).

The ability to overwrite information in a flash memory chip is used by some software viruses to destroy BIOS data.

In this case, to restore the computer to working capacity, either the replacement of the chip that stores the BIOS is required, or reprogramming using special software tools.

Software viruses enter your computer when you run unchecked programs received on external media (floppy disk, CD, etc.) or received from the Internet. Particular attention should be paid to the words at startup. During normal copying of infected files, the computer cannot become infected. In this regard, all data received from the Internet must undergo mandatory verification.

on security, and if unsolicited data is received from an unknown source, it should be destroyed without consideration. A common technique for distributing "Trojans" is to attach to an email with a "recommendation" to extract and run a supposedly useful program.

boot viruses.

Boot viruses differ from software viruses in the way they spread. They hit not program files, certain system areas of magnetic media (floppy and hard disks). In addition, when the computer is turned on, they can be temporarily located in RAM.

Usually, infection occurs when a computer is booted from magnetic media, the system area of ​​which contains a bootable virus. So, for example, when you try to boot a computer from a floppy disk, the virus first penetrates into the RAM, and then into boot sector hard drives. Further, this computer itself becomes a source of distribution of a boot virus.

Macroviruses.

This particular type of virus infects documents executed in some application programs. Having the means to carry out the so-called macros. In particular, such documents include documents of the word processor Microsoft Word (they have the extension

doc). Infection occurs when a document file is opened in the program window, unless the ability to execute macros is disabled in the program.

As with other types of viruses, the result of an attack can be either relatively harmless or destructive.

The main types of computer viruses.

Currently, more than 5,000 software viruses are known, they can be classified according to the following features (Fig. 1):

habitat;

the method of contamination of the environment;

impact;

features of the algorithm.

Fig.1 Classification of computer viruses:

a - by habitat; b - according to the method of infection;

c - according to the degree of impact; d - according to the features of the algorithms.

Depending on the habitat viruses can be divided into network, file, boot and file-boot.

Network viruses distributed over various computer networks.

File viruses are implemented mainly in executable modules, i.e. to files with COM and EXE extensions. File viruses can also infect other types of files, but as a rule, they are written in such files, they never get control and, therefore, lose the ability to reproduce.

Boot viruses are embedded in the boot sector of the disk (Boot) or in the sector containing the boot program system disk(Master Boot Record).

File-boot viruses infect both files and boot sectors of disks.

According to the mode of infection Viruses are divided into resident and non-resident.

Resident virus when infecting a computer, it leaves its resident part in RAM, which then intercepts the operating system's access to infected objects (files, boot sectors, etc.) and injects itself into them. Resident viruses reside in memory and remain active until shutdown or restart. computer boot.

Non-resident viruses do not infect computer memory and are active for a limited time.

By degree of impact Viruses can be divided into the following types:

non-hazardous not interfering with the operation of the computer, but reducing the amount of free RAM and disk space, the actions of such viruses are manifested in any graphic or sound effects;

dangerous viruses that can lead to various malfunctions of the computer;

very dangerous, the impact of which may lead to loss of programs, destruction of data, erasure of information in the system areas of the disk.

How do viruses spread?

There are several ways, primarily through floppy disks. If you received a floppy disk from a friend who has a virus in his computer, then most likely the disk will be infected. There are two options here. The first is that the virus is located in the system area of ​​the disk, and the second is that there are one or more infected files. As already mentioned, the virus must take control, so if this is a system floppy, then booting from it can infect the computer. If this is a system floppy disk, and you tried to boot a computer from it and a message appeared on the screen: Non system disk (non-system disk), then in this case you could infect your computer, since any floppy disk has an operating system loader and when you turn it on, it will take control.

The second option is infected files. Not all files can be infected. So, for example, if there is a text of a letter or some other document typed using the Norton Commander editor, then there will be no virus. Even if he accidentally ended up there, then by viewing the file using the same editor or the like, you can see incomprehensible characters at the very beginning or end of such a file that are best destroyed. Other editors create files that contain control information, such as font size or type, indents, different conversion tables, etc. As a rule, it is almost impossible to get infected through such a file. However, the Word 6.0 and 7.0 editors have the ability to contain macro commands at the very beginning of the document, to which control will be transferred, and thus a virus can spread through documents.

Other ways of spreading viruses are transferring them on other media, such as CD-ROMs, which is quite rare. It happened that when buying licensed software, it turned out to be infected with a virus, but such cases are extremely rare.

The peculiarity of CD - ROM-disks is that information is not recorded on them. If a virus-free CD - ROM disk has been in an infected computer, this will not make it infected. However, if information infected with a virus is recorded on it, then in this case no antivirus programs will be able to clean the disk from viruses.

The most common way for viruses to spread is through a network of computers, and in particular the Internet, when other programs, such as games, are rewritten and run. There may be other, quite rare cases, when another hard drive that has been infected is inserted into the computer. To avoid this, boot from the system floppy and either check the hard drive with special anti-virus programs, or, better, partition and format the drive with Fdisk and Format.

Detection of computer viruses

To detect viruses, there are special anti-virus programs that allow you to detect and destroy viruses. However, not all viruses can be detected, as more and more of their forms appear.

An antivirus program is like a medicine, that is, it acts selectively on some viruses, skipping others. So if an anti-virus program is launched on a computer every day (week, month), then there is still no absolute certainty that it will detect viruses.

There is a fairly wide selection of antivirus programs. These are Aidstest (Lozinsky), Dr Web, Norton antivirus for Windows, DSAV kit and others. According to the way they work, they can be divided into three types:

1) Detectors producing scanning. This is the simplest and most common form, which involves viewing files and boot records in order to check their contents for a signature (signature - code virus program). In addition to scanning for a signature, a heuristic analysis method can be used: by checking the codes to identify virus-specific codes, the detectors remove the detected viruses, called polyphages. Such programs can perform heuristic analysis and detect new viruses.

2) auditors- programs that remember the state of files and system areas, often by calculating the checksum or file size.

3) Programs - filters, or resident watchmen, permanently located in the computer's RAM and analyzing executable files and inserted floppy disks. They inform the user about an attempt to change the boot sector, the appearance of a resident program, the possibility of writing to disk, etc.

4) Hardware protection is a controller that plugs into an expansion slot and monitors calls to flex and hard drives. you can protect certain parts, such as boot records, executable files, configuration files, etc. Unlike the previous methods, it can also work when the computer is infected.

5) There are also programs installed in BIOS computer, when a message appears on the screen when trying to write to the boot sector.

Preventive measures against viruses

For prevention you need:

1. Perform data archiving. Archiving is the recording of files on removable media. Most often, this role is played by floppy disks or magnetic tapes used in special devices (streamers). For example, there is no need to memorize Windows files if you have an installation disk that can be used to reboot the system and restore files. Therefore, if the computer has only floppy disks from removable devices, then you need to remember information that is difficult to recover.

Archiving. As a rule, information is written to more than one disc. Let's say the information is placed on one floppy disk, and copying is done once a week. First, the information is recorded on August 4, the next time on August 11, the recording is made on another floppy disk from the same directories. On August 18, the recording takes place again on the first floppy disk, on August 25 on the second, then again on the first and so on, for this you need to have at least two diskettes. The fact is that when writing to a floppy disk, a failure may occur and most of the information will be lost. On a home computer, it is necessary to copy from time to time, the frequency is determined by the user himself.

2. To the whole information received from other computers, checked antivirus programs. Previously, it was already written that some files, for example, with graphic information, are quite safe from the point of view of virus infection. Therefore, if only this kind of information is on a diskette, then this information is not dangerous. If a virus is detected, then you need to check all computers that were connected to the infected via floppy disks, network. It is necessary to remove the virus not only from the hard drive, but also from floppy disks and archive files. If there is a suspicion of the existence of a virus in the computer, or information is transferred to the computer using floppy disks or the Internet, then you can install antivirus programs inAutoexec. INat so that when you turn on the computer, they start working.

3. Do not boot from unknown floppy disks. When booting from a hard drive, make sure there are no floppy disks in drive A: or B:, especially from other machines.

Conclusion

The mass use of personal computers, unfortunately, turned out to be associated with the emergence of self-reproducing virus programs that prevent the normal operation of the computer, destroy the file structure of disks and damage the information stored in the computer.

Computer virus- a specially created program designed to perform certain actions that interfere with working on a computer.

Having penetrated into one computer, a computer virus is able to spread to other computers.

The virus program is written in Assembly language to be small and fast, although there are programs written in C, Pascal, and other languages. Many resident virus programs use the principles developed in drivers, that is, they set the address of the virus program in the interrupt table, and after the end of the virus, they transfer control to the regular program, the address of which was previously in the interrupt table. This is called control takeover.

There are automated programs for creating new viruses that allow you to create the source code of the virus online in assembly language. When entering the package, you can set options to specify what destructive actions the virus will perform, whether it will encrypt its machine code text, how quickly it will infect files on disks, and so on.

The main thing for a virus is to get control in order to start its work. If the virus immediately began to perform the action that is inherent in it, then it would be easier to identify it and clean the computer from it. The difficulty lies in the fact that viruses may not appear immediately when they appear on a computer, but after certain time e.g. on a certain day.

In the modern world, there are many antivirus programs that can detect and destroy viruses. However, not all viruses can be detected, as more and more of their forms appear.

To prevent a virus program from spoiling the anti-virus program, it should be loaded from the system diskette by booting the computer from the system disk and starting the anti-virus program.

Keep your anti-virus software up to date, as later versions may detect more types of viruses. To update the latest versions of anti-virus programs, you can receive them via a modem, and you can also call specialists from anti-virus companies.

Bibliography

A. Kostov, V. Kostov. Big encyclopedia. Everything about the personal computer. - M .: "Martin", 2003. - 720s.

Informatics: Textbook. - 3rd revision. ed. / Ed. N. V. Makarova. - M.: Finance and statistics, 2005. - 768 p.: ill.

Informatics for lawyers and economists. / Under the editorship of S. V. Simonovich and others - St. Petersburg: St. Petersburg, 2001. - 688 p.6 ill.

virus- variety computer programs, the distinguishing feature of which is ... the protection of information in computers, the fight against computer viruses, child porn sites and information security...

Introduction………………………….…………………………………………………3

1. Computer viruses. Classification…………………………………….4

2. Creators of malware……………………………………………...5

3. Description of malware……………………………………………....6

3.1. Polymorphic viruses ……………………………………………………7

3.2. Stealth viruses…………………………………………………………………7

3.3Trojan viruses…………………………………………………………….7

3.4 Worms………………………………………………………………………..8

4. Signs of the appearance of viruses……………………………………………………8

5. Fight against antiviruses…………………………………………………………..9

Conclusion…………………………………………………………………………10

List of used literature………………………………………………..11

Introduction

Computers have become real helpers of a person and no one can do without them. commercial firm or a government organization. However, in connection with this, the problem of information security has become especially acute.

Viruses that have become widespread in computer technology, shocked the whole world. Many computer users are concerned about rumors that cybercriminals use computer viruses to break into networks, rob banks, and steal intellectual property.

Today, the mass use of personal computers, unfortunately, turned out to be associated with the emergence of self-reproducing virus programs that prevent the normal operation of a computer, destroy the file structure of disks and damage the information stored in a computer.

Increasingly, there are reports in the media about various kinds of pirate tricks of computer hooligans, about the emergence of more and more advanced self-propagating programs. Quite recently, the infection of text files with a virus was considered absurd - now you will not surprise anyone with this. Despite the laws adopted in many countries to combat computer crimes and the development of special software to protect against viruses, the number of new software viruses is constantly growing. This requires the user of a personal computer to be knowledgeable about the nature of viruses, how to infect and protect against viruses.

1. Computer viruses

computer virus is a program (some set of executable code/instructions) that is able to create copies of itself (not necessarily identical to the original) and embed them into various objects/resources of computer systems, networks, etc. without the knowledge of the user. At the same time, copies retain the ability to further distribution.

Virus classification:

1) according to the habitat of the virus

File viruses most often they are embedded in executable files with the extensions .exe and .com (the most common viruses), but they can also be embedded in files with operating system components, drivers external devices, object files and libraries, into command batch files, program files in procedural programming languages ​​(they infect executable files during translation).

Boot viruses are embedded in the floppy boot sector (boot-sector) or in the sector containing the system disk boot program (master boot record). When booting DOS from an infected disk, such a virus changes the program bootstrap or modify the file allocation table on the disk, making it difficult for the computer to operate or even making it impossible to start the operating system.

File-boot viruses integrate the capabilities of the two previous groups and have the greatest "efficiency" of infection.

Network viruses use commands and protocols of telecommunication systems for their distribution ( Email, computer networks).

Document viruses(often referred to as macro viruses) infect and corrupt text files (.doc) and files spreadsheets some popular editors.

Combined network macro viruses not only infect created documents but also send copies of these documents by e-mail.

2) according to the method of environmental contamination;

Residential virus when infecting a computer, it leaves its resident part in RAM, which then intercepts the operating system's calls to infected objects and injects itself into them. Non-resident viruses do not infect computer memory and are active for a limited time.

3) by destructive possibilities

Harmless those. that do not affect the operation of the computer in any way (except for the reduction of free disk space as a result of its distribution);

Non-hazardous , the influence of which is limited to a decrease in free disk space and graphic, sound, etc. effects;

4) according to the features of the virus algorithm .

Companion viruses (companion) are viruses that do not modify files.

Viruses are "worms" (worm)- viruses that spread in computer network and, like companion viruses, do not modify files or sectors on disks. They penetrate into the memory of a computer from a computer network, calculate the network addresses of other computers and send copies of themselves to these addresses. Such viruses sometimes create working files on system disks, but may not access computer resources at all (with the exception of RAM).

2. Malware creators

The bulk of viruses and Trojans in the past were created by students and schoolchildren who had just learned a programming language, wanted to try their hand, but could not find a more worthy application for them. Such viruses were written and are being written to this day only for the self-affirmation of their authors.

The second group of virus creators are also young people (usually students) who have not yet fully mastered the art of programming. From the pen of such "craftsmen" viruses often come out extremely primitive and with a large number errors ("student" viruses). The life of such virus writers has become much easier with the development of the Internet and the emergence of numerous websites focused on teaching how to write computer viruses. Often here you can find ready-made source code, in which you just need to make minimal "author's" changes and compile in the recommended way.

The third, most dangerous group that creates and launches "professional" viruses into the world. These carefully designed and fine-tuned programs are created by professional, often very talented programmers. Such viruses often use rather original algorithms for penetrating into system data areas, errors in the security systems of operating environments, social engineering, and other tricks.

Separately, there is a fourth group of virus authors - "researchers", who are engaged in the invention of fundamentally new methods of infection, hiding, counteracting antiviruses, etc. Often, the authors of such viruses do not distribute their creations, but actively promote their ideas through numerous Internet resources dedicated to creating viruses. At the same time, the danger posed by such "research" viruses is also very great - having fallen into the hands of "professionals" from the previous group, these ideas very quickly appear in new viruses.

3. Description of malware

Malicious software includes network worms, classic file viruses, Trojan horses, hack tools, and other programs that knowingly cause harm to the computer they run on or to other computers on the network.

3.1Polymorphic viruses

Polymorphic viruses- viruses that modify their code in infected programs in such a way that two instances of the same virus may not match in one bit. This type of computer virus is by far the most dangerous. Such viruses not only encrypt their code using different encryption paths, but also contain the generation code of the encryptor and decryptor, which distinguishes them from ordinary encryption viruses, which can also encrypt sections of their code, but at the same time have a constant code of the encryptor and decryptor.

3.2 Stealth viruses

Stealth viruses deceive anti-virus programs and as a result go unnoticed. However, there is an easy way to disable the stealth virus cloaking mechanism. It is enough to boot the computer from a non-infected system floppy disk and immediately, without running other programs from the computer disk (which may also be infected), scan the computer with an anti-virus program. When loaded from a system floppy, a virus cannot gain control and install a resident module in RAM that implements a stealth mechanism. Antivirus program will be able to read the information actually written on the disk and easily detect the virus.

3.3Trojan viruses

Trojan horse- this is a program that contains some destructive function, which is activated when a certain trigger condition occurs. Usually such programs are disguised as some useful utilities. "Trojan horses" are programs that implement, in addition to the functions described in the documentation, some other functions related to security breaches and destructive actions. Cases of creating such programs in order to facilitate the spread of viruses have been noted. Lists of such programs are widely published in the foreign press. They usually disguise themselves as gaming or entertainment programs and cause harm with beautiful pictures or music.

Software bookmarks also contain some function that damages the aircraft, but this function, on the contrary, tries to be as inconspicuous as possible, because. the longer the program does not arouse suspicion, the longer the bookmark will be able to work.

3.4Worms

Worms called viruses that spread over global networks, affecting entire systems, not individual programs. This is the most dangerous type of virus, as the objects of attack in this case are Information Systems state scale. With the advent of the global Internet networks this type of security breach poses the greatest threat, as any of the 40 million computers connected to this network could be exposed to it at any time.

4. Signs of the appearance of viruses

When a computer is infected with a virus, it is important to detect it. To do this, you should know about the main signs of the manifestation of viruses. These include the following:

1. cessation of work or incorrect operation of previously successfully functioning programs

2. slow work computer

3. inability to boot the operating system

4. Disappearance of files and directories or distortion of their contents

5. change the date and time of file modification

6. resizing files

7. unexpected large increase in the number of files on the disk

8. significant reduction in the size of free RAM

9. displaying unexpected messages or images

10. giving unintended sound signals

11. frequent freezes and computer crashes

It should be noted that the above phenomena are not necessarily caused by the presence of the virus, but may be due to other causes. Therefore, it is always difficult to correctly diagnose the state of the computer.

5. Fight against antiviruses

At all times, there have been malicious programs that protect themselves quite actively. Such protection can be:

Targeted search in the system of an antivirus, firewall or other security utility and disruption of its operation. An example is when a malware searches for the name of a specific antivirus in the process list and tries to unload that antivirus;

Blocking files and opening them with exclusive access as a countermeasure against file antiviruses;

Modification hosts file in order to block access to anti-virus update sites;

Detection of prompt windows from the security system and simulation of pressing the "Allow" button.

In fact, a targeted attack on the defenses is more of a "forced measure", a defense of the pinned against the wall, than an active offense. In modern conditions, when antiviruses analyze not only the code of malicious programs, but also their behavior, the latter are more or less unarmed: neither polymorphism, nor packaging, nor even the technology of hiding in the system provides them with full protection. Therefore, malware can only target specific manifestations or functions of the “enemy”. Outside of unavoidable necessity, this method of self-defense would not be so popular, since it is too disadvantageous from the point of view of the widest possible protection.

Conclusion

From the foregoing, we can conclude that a computer virus is a specially written small-sized program that can “attribute” itself to other programs, as well as perform various unwanted actions on a computer. A program that contains a virus is called "infected". When such a program starts, the virus first takes control. The virus finds and "infects" other programs, and also performs some harmful actions (for example, it corrupts files or the file allocation table on the disk, "contaminates" RAM, etc.). A virus is a program that has the ability to reproduce itself. This ability is the only property common to all types of viruses. A virus cannot exist in "complete isolation". This means that today it is impossible to imagine a virus that would not somehow use the code of other programs, information about the file structure, or even just the names of other programs. The reason for this is quite clear: the virus must somehow ensure that control is transferred to itself.

The most effective way to protect against computer viruses is not to enter information into the computer from the outside. But, unfortunately, it is almost impossible to protect yourself from viruses 100% (it is understood that the user exchanges floppy disks with friends and plays games, and also receives information from others).

Bibliography

1. Leontiev V.P. The latest encyclopedia of the personal computer 2003.- 5th ed., revised. and additional - M.: OLMA-PRESS, 2003

2. Levin A.Sh. Self-instruction manual for working on a computer. - 9th ed., St. Petersburg: St. Petersburg, 2006

3. www.yandex. en

4. www.google. en

4. CD-ROM. Best of the best: essays, term papers, diplomas, 2007

Varieties of viruses

Parameter name	Meaning
Article subject:	Varieties of viruses
Rubric (thematic category)	Computers

What are Viruses, the history of creation

Viruses

John von Neumann in 1951 proposed a method for creating self-reproducing mechanisms

The appearance of the first computer viruses is erroneously attributed to the 1970s and even the 1960s. Usually referred to as ʼʼvirusesʼʼ such programs as Animal, Creeper, Cookie Monster (the first and last in modern terminology are worms, CREEPER was neither a virus nor a worm, but a self-moving program, that is, when on remote computer launched new copy CREEPER, the previous copy stopped working.)

Viruses spread by copying their body and ensuring its subsequent execution: embedding themselves in the executable code of other programs, replacing other programs, registering themselves in autorun, and more. A virus or its carrier are not only programs containing machine code, but also any information containing automatically executable commands - for example, batch files and Microsoft Word and Excel documents containing macros. However, to penetrate a computer, a virus can use vulnerabilities in a popular software(For example, Adobe Flash, Internet Explorer, Outlook), for which distributors embed it in ordinary data (pictures, texts, etc.) along with an exploit that exploits the vulnerability.

When they reproduce, worms only copy their code to some disk directories in the hope that these new copies will someday be run by the user.

The first known viruses are Virus 1,2,3 and Elk Cloner for Apple II PCs. Both viruses are very similar in functionality and appeared independently of each other with a short time interval in 1981.

A computer virus was named after biological viruses for a similar propagation mechanism.

Apparently, the first use of the word ʼʼvirusʼʼ in relation to a program was by Gregory Benford in the fantasy story ʼʼThe Scarredʼʼ, published in Venture magazine in May 1970.

The first antivirus - 1984.

Viruses spread by copying their body and ensuring its subsequent execution: embedding themselves in the executable code of other programs, replacing other programs, registering themselves in autorun, and more. A virus or its carrier are not only programs containing machine code, but also any information containing automatically executable commands.

according to the habitat of the virus

‣‣‣ File viruses

‣‣‣ Boot viruses

‣‣‣ Combined network macro viruses

‣‣‣ Document viruses

‣‣‣ Network viruses

‣‣‣ File-bootable

According to the method of contamination of the habitat:

Resident virus- when a computer is infected, it leaves its resident part in RAM, which then intercepts the operating system's calls to the infected objects and injects itself into them.

Non-resident viruses do not infect computer memory and are active for a limited time.

By destructive possibilities:

1. harmless (do not affect the operation of the computer, except for the reduction of free memory due to its distribution)
2. non-hazardous (reduce free memory on disk)
3. dangerous (lead to failures)
4. Very dangerous (damage to parts of mechanisms, loss of programs, destruction of data)

According to the features of the virus algorithm .

Companion viruses are viruses that do not modify files.

Worm viruses are viruses that spread over a computer network and, like their companion viruses, do not modify files or sectors on disks. Οʜᴎ penetrate into the memory of a computer from a computer network, calculate the network addresses of other computers and send their copies to these addresses. Such viruses sometimes create working files on system disks, but may not access computer resources at all (with the exception of RAM).

Polymorphic viruses- viruses that modify their code in infected programs in such a way that two instances of the same virus may not match in one bit. This type of computer virus is by far the most dangerous. Such viruses not only encrypt their code using different encryption paths, but also contain the generation code of the encryptor and decryptor, which distinguishes them from ordinary encryption viruses, which can also encrypt sections of their code, but at the same time have a constant code of the encryptor and decryptor.

Stealth viruses - They cheat antivirus programs and as a result go unnoticed. However, there is an easy way to disable the stealth virus cloaking mechanism. It is enough to boot the computer from a non-infected system floppy disk and immediately, without running other programs from the computer disk (which may also be infected), scan the computer with an anti-virus program. When loaded from a system floppy, a virus cannot gain control and install a resident module in RAM that implements a stealth mechanism. The anti-virus program will be able to read the information actually written on the disk and easily detect the virus.

Trojan horses (Especially for Den =)) - this is a program that contains some destructive function that is activated when a certain trigger condition occurs. Usually such programs are disguised as some useful utilities. ʼʼTrojan horsesʼʼ are programs that implement, in addition to the functions described in the documentation, some other functions associated with security breaches and destructive actions. Cases of creating such programs in order to facilitate the spread of viruses have been noted. Lists of such programs are widely published in the foreign press. They usually disguise themselves as gaming or entertainment programs and cause harm with beautiful pictures or music.

Worms - viruses that spread over global networks, infecting entire systems, not individual programs. This is the most dangerous type of virus, as the objects of attack in this case are information systems of a national scale. With the advent global network Internet, this type of security breach poses the greatest threat, since any of the 40 million computers connected to this network can be exposed to it at any time.

Varieties of viruses - concept and types. Classification and features of the category "Varieties of viruses" 2017, 2018.

Content

A person is most susceptible to various colds in the autumn and spring. Viral infectious diseases - a type of disease that causes an infection that has penetrated into a weakened body. They can show up in an acute form or sluggish, but treatment should be carried out in both cases, so as not to aggravate the situation, to avoid dangerous complications. A person on average gets sick from 2 to 3 times a year with catarrhal pathologies, but the disease always develops due to viral DNA.

What are viral diseases

Types of viruses

Can cause symptoms of pathology different types bacteria that differ in location, rate of development, signs. Human viruses have a special classification, conventionally they are divided into rapid and slow. The second option is very dangerous because the symptoms are very weak and it is not possible to immediately detect the problem. This gives her time to multiply, to strengthen. Among the main types of viruses, the following groups are distinguished:

1. Orthomyxoviruses all influenza viruses.
2. adenoviruses and rhinoviruses. Provoke ARVI - acute respiratory viral infection that affects the respiratory system. Symptoms are very similar to the flu, can cause complications (bronchitis, pneumonia)
3. Herpesviruses- herpes viruses, which can for a long time live in the body asymptomatically, are activated immediately after the weakening of the immune system.
4. Meningitis. It provokes meningococcal infection, the brain mucosa is damaged, the virus feeds on cerebrospinal fluid (cerebrospinal fluid).
5. Encephalitis- affects the membrane of the brain, provokes irreversible disturbances in the work of the central nervous system.
6. parvovirus which is the causative agent of poliomyelitis. A very dangerous disease that can cause convulsions, inflammation of the spinal cord, paralysis.
7. picornaviruses- causative agents of viral hepatitis.
8. Orthomyxoviruses- cause mumps, measles, parainfluenza.
9. Rotavirus- cause enteritis, intestinal flu, gastroenteritis.
10. rhabdoviruses- causative agents of rabies.
11. Papoviruses Cause of human papillomatosis.
12. Retroviruses- the causative agents of AIDS, first develops HIV, and then AIDS.

List of human viral diseases

Medicine knows a huge number of contagious viruses and infections that can provoke various diseases in the human body. Below are only the main groups of diseases that are likely to be encountered:

1. One of the largest groups of viral diseases - influenza (A, B, C), different types of colds that cause inflammation in the body, high fever, general weakness and sore throat. Therapy is carried out with the help of restorative agents, antiviral drugs, if necessary, antibacterial drugs are prescribed.
2. Rubella. A common childhood pathology, less common in adults. Symptoms include damage to the membranes of the respiratory tract, skin. eyes, lymph nodes. The virus is transmitted by droplets, always accompanied by high fever, skin rashes.
3. Piggy. A dangerous viral disease affecting the respiratory tract, the salivary glands are severely affected. Rarely found in adult men, testes are affected by this virus.
4. Measles- often found in children, the disease affects the skin, respiratory tract, intestines. It is transmitted by airborne droplets, the causative agent is paramyxovirus.
5. Poliomyelitis (infantile paralysis). Pathology affects the respiratory tract, intestines, then penetrates into the blood. Next, the motor neurons are damaged, which leads to paralysis. The virus is transmitted by droplets, sometimes a child can become infected through stool. In some cases, insects act as carriers.
6. Syphilis. This disease is sexually transmitted, it affects the genitals. Then it affects the eyes, internal organs and joints, heart, liver. Antibacterial agents are used for treatment, but it is very important to determine the presence of pathology immediately, because it may not cause symptoms for a long time.
7. Typhoid. It is rare, characterized by a rash on the skin, damage to blood vessels, which leads to the formation of blood clots.
8. Pharyngitis. The disease provokes a virus that enters the human body along with dust. Cold air, streptococci, staphylococci can also provoke the development of pathology. Accompanied by a viral disease fever, cough, sore throat.
9. Angina- a common viral pathology, which has several subspecies: catarrhal, follicular, lacunar, phlegmonous.
10. Whooping cough. This viral disease is characterized by damage to the upper respiratory tract, swelling of the larynx is formed, severe coughing attacks are observed.

The most rare human viral diseases

Most viral pathologies are contagious diseases that are transmitted sexually, by airborne droplets. There are a number of diseases that are extremely rare:

1. Tularemia. Pathology in its symptoms strongly resembles the plague. Infection occurs after Francisella tularensis enters the body - this is an infectious bacillus. As a rule, it enters along with the air or when bitten by a mosquito. The disease is also transmitted from a sick person.
2. Cholera. This disease is very rare in modern medical practice. Vibrio cholerae virus, which enters the body through dirty water, contaminated food, causes symptoms of pathology. The last outbreak of pathology was recorded in 2010 in Haiti, the disease claimed the lives of more than 4,500 people.
3. Creutzfeldt-Jakob disease. A very dangerous pathology that is transmitted through the meat of infected animals. The causative agent is considered to be a prion - a special protein that begins to actively destroy body cells after penetration. The insidiousness of the pathology lies in the absence of symptoms, a personality disorder begins in a person, severe irritation and dementia appear. It is impossible to cure the disease and the person dies within a year.

Virus Symptoms

Symptoms do not always appear immediately, some types of viral diseases can occur for a long time without obvious signs, which becomes a problem with further treatment. Each infectious disease goes through the following stages:

• incubation period;
• premonitory;
• the height of pathology;
• recovery.

The duration of the first stage always depends on the specific type of virus and can last from 2-3 hours to six months. Symptoms will differ depending on the developing disease, but, as a rule, the following manifestations are among the common symptoms of viral pathologies:

• soreness, muscle weakness;
• slight chills;
• persistent body temperature;
• sensitivity of the skin when touched;
• cough, sore throat, watery eyes;
• dysfunction of some organs;
• swollen lymph nodes.

Temperature during a viral infection

This is one of the main reactions of the body to the penetration of any pathogen. Temperature is a defense mechanism that activates all other immune functions to fight viruses. Most diseases occur with a high body temperature. Viral pathologies that provoke this symptom include:

• flu;
• SARS;
• tick-borne encephalitis;
• childhood diseases: chicken pox, infectious parotitis, rubella, measles;
• polio;
• Infectious mononucleosis.

Often there are cases of the development of diseases, in which the temperature does not rise. The main symptoms are watery compartments with a runny nose, sore throat. The absence of temperature is due to the insufficient activity of the virus or the immunity is strong, therefore, it does not fully use all possible methods of fighting the infection. If the growth has begun, then high rates are kept, as a rule, for about 5 days.

signs

Most viruses provoke the development of acute respiratory pathologies. There is some difficulty in identifying diseases that were caused by bacteria, because the treatment regimen in this case will be very different. There are more than 20 varieties of viruses that cause SARS, but their main symptoms are similar. The primary symptoms include the following:

• rhinitis (runny nose), cough with clear mucus;
• low temperature (up to 37.5 degrees) or fever;
• general weakness, headaches, poor appetite.

How to distinguish a cold from a virus

There is a difference between these two concepts. A cold occurs when you stay in the cold for a long time, severe hypothermia of the body, which leads to a weakening of the immune system and the appearance of an inflammatory process. This is not the name of the disease, but only the cause of the development of other pathologies. Viral pathology often becomes a consequence of a cold, because the body does not have enough defenses to resist the pathogen.

Virus Diagnostics

When contacting a doctor, he must visual inspection and collect history. Usually. viral diseases are accompanied by fever, cough, runny nose, but after 3-4 days a person feels better. Specialists can determine the type of disease by general symptoms or based on seasonal outbreaks of diseases, for example, influenza epidemics often begin in winter, and SARS in autumn. Determination of the exact type of virus will be required for specific treatment (HIV, syphilis, etc.). For this, a virological study is used.

This method in medicine is the "gold standard", which is carried out in a special laboratory. As a rule, such methods are used during epidemic outbreaks of viral infectious diseases. Methods of immunodiagnostics (immunoindication, serodiagnosis) have found wide distribution for diagnosing pathogens. They are implemented through a variety of immune responses:

• enzyme immunoassay (ELISA);
• radioisotope immunoassay (RIA);
• hemagglutination inhibition reaction;
• complement fixation reaction;
• immunofluorescence reaction.

Treatment of viral diseases

The course of therapy is depending on the type of pathogens. For example, if it is necessary to treat SARS, childhood viral pathologies (mumps, rubella, measles, etc.), then all medicines are used to eliminate symptoms. Subject to bed rest, diet, the body itself copes with the disease. Treatment of viruses is carried out in cases where they cause tangible discomfort to a person. Apply for example:

• antipyretics if the temperature is above 37.5 degrees;
• vasoconstrictor drops are used to relieve swelling of the nose;
• in rare cases, antibiotics (if a bacterial infection has joined);
• NSAIDs that relieve pain and lower the temperature, for example, aspirin, paracetamol, ibuprofen.

During treatment, doctors recommend drinking more fluids to combat intoxication of the body, moderate nutrition, bed rest and humidity in the room at least 50% where the patient is located. Therapy for influenza is no different, but the doctor must be sure to monitor the patient, because this disease can cause serious consequences. One of them is pneumonia, which can lead to pulmonary edema and death.

If such complications have begun, then treatment must be carried out in a hospital with the use of special medications (Zanamivir, Oseltamivir). When diagnosing the human papillomavirus, the therapy consists in maintaining immunity in good shape, surgical removal of warts, genital warts. In cases of severe viral pathologies. For example, HIV requires a course of antiretroviral drugs. It cannot be eliminated completely, but it can be kept under control and prevent the spread of the disease.

When genital herpes is infected, it is necessary to take special preparations, their maximum effectiveness is confirmed in the first 48 hours. If you use the funds later, their medicinal effect is significantly reduced and the course of treatment can last from several weeks to several months. Herpes on the lips should be treated with local remedies (ointments, gels), but even without them, the wound heals within a week.

Antivirals

In medicine, there is a certain number of medicines of this group, which have proven their effectiveness and are used constantly. The entire list of drugs is conditionally divided into two types:

1. Medicines that stimulate the human immune system.
2. Means that attack the detected virus are direct-acting drugs.

The first group refers to broad-spectrum agents, but their use leads to serious complications. One example of such drugs is interferons and the most popular of these is interferon alfa-2b. It is prescribed for the treatment of chronic forms of Hepatitis B, and was previously prescribed for hepatitis C. Patients had a hard time tolerating such therapy, which led to side effects from the central nervous system and the cardiovascular system. In some cases, pyrogenic properties are manifested - they cause fever.

The second type of PPD medications is more effective and easier to tolerate by patients. Among the popular drugs, the following treatment options are distinguished:

1. Herpes- acyclovir. Helps to overcome the symptoms of the disease, but does not kill it completely.
2. Flu Influenza neuraminidase inhibitors (Zanamivir, Oseltamivir). Current influenza strains have developed resistance to previous drugs (adamantanes) and are not effective. Name of drugs: Relenza, Ingavirin, Tamiflu.
3. Hepatitis. For the treatment of group B viruses, interferons are used together with Ribavirin. For hepatitis C, a new generation of drugs is used - Simeprevir. Its effectiveness reaches 80-91% of a persistent virological response.
4. HIV. It cannot be completely cured, antiretroviral drugs provide a lasting effect, cause remission, and a person cannot infect others. The therapy continues throughout life.

Prevention

Preventive measures may vary slightly depending on the type of virus. For example, to prevent infection with hepatitis or HIV, it is necessary to protect yourself during sexual intercourse. There are two main areas of prevention of viral diseases:

1. specific. It is carried out to develop specific immunity in humans through vaccination. A person is injected with a weakened strain of the virus so that the body develops antibodies to it. This will help protect you from measles, influenza, polio, hepatitis (liver disease). Most life-threatening diseases can be prevented with vaccines.
2. Nonspecific. Strengthening the immune defense of a person, a healthy lifestyle, physical activity and normal nutrition. A person must follow the rules of hygiene, which will protect him from intestinal infections, be protected during sexual intercourse in order to prevent HIV infection.