Computer viruses: names, description, methods of infection and control

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Computer viruses: names, description, methods of infection and control
Computer viruses: names, description, methods of infection and control

Questions related to what are computer viruses and their names, what are the ways they penetrate the system and the impact on computers or user data, ordinary users usually do not care at all until a certain point. But when the operating system or the programs installed in it begin to behave completely inappropriately, many begin to look for answers, but it is often too late. But there are many cases when the OS (most often this applies to Windows systems) is not something that does not work correctly, but may even turn out to be blocked or completely fail. Let's try to figure out what computer viruses are. The names of the main threats will also be given, but it’s worth saying right away that the classification below is purely conditional, since today there is a unified structured system for recognizing computer threats and classifying them asa certain class does not exist. And this is mainly due only to the fact that more and more often there are mixed types of threats that are simply impossible to include in any particular class.

The simplest classification of computer threats

So, for starters, let's consider the simplest division of threats into main types. It is believed that viruses and worms are the main ones at the moment.

The difference between viruses and worms
The difference between viruses and worms

The difference between these two big categories is that the former penetrate computers through malicious files and inject their own codes into programs, while the latter can infect files of a strictly specific type (for example, all EXE-format objects, office documents or multimedia content). Such a division does not allow a clear understanding of the full difference between some types of threats, therefore, for a more detailed classification, additional features are used, which will be discussed below.

Ways to introduce threats to computers

But let's leave the names of computer viruses aside for now, and pay special attention to finding out exactly how threats can penetrate user computers. Most often, experts identify several main loopholes here:

  • vulnerability of the operating system and browsers used for web surfing;
  • removable media;
  • networks;
  • poor quality of antivirus software;
  • Stupidity or carelessness of the user himself.

As far as operating systems are concerned, it is naïve to believe that virusesaffect only legacy DOS systems or Windows. Until recently, it was believed that virus threats do not work in the environment of "apple" and UNIX-like operating systems, including Linux. However, now an absolutely confirmed fact is the impact of viruses and malicious codes with the incapacitation of the same iPhones running on iOS, or Android devices whose operating systems are based on the Linux kernel.

With browsers, I think, everything is clear, because when visiting unreliable resources that may contain threats, using the same Internet Explorer, you can pick up viruses quite elementarily, and not only when downloading some files, but and just by logging into a site that can automatically execute ActiveX scripts.

The quality of antiviruses can also play a trick on the user, since some of the widely advertised and praised antiviruses are unable to fully protect the computer and user information from threats. In this case, advertising virus applets can be called a striking example, many of which even have security certificates.

An example of a virus on a flash drive
An example of a virus on a flash drive

On removable media, threats are most often present in the form of autorun files (Autorun.inf), and when connected to a PC or laptop, computer viruses infect the device when it is triggered.

As for the inattention of users, this most often manifests itself when installing programs downloaded from dubious sources(for example, from torrent trackers) when they do not pay attention to offers to install accompanying supposedly partner software, which actually turns out to be an adware or spyware type virus. Well, we are not talking about ignoring antivirus warnings that may appear when you try to go to virus-containing sites on the Internet.

Besides, when computers are combined in a network, threats can be transmitted from one infected terminal to all the others through gaps in the network that does not have an antivirus or firewall.

Signs of a computer system infection

Due to the impact, which may take some time to manifest itself, the system starts to slow down with an unreasonably high load on system resources (CPU, RAM or hard disk).

Blue screen of death
Blue screen of death

Sometimes installed applications stop working, or driver errors occur, which can lead to the notorious blue screens. Finally, the browser can be flooded with ads, but, the saddest thing, sometimes some files are blocked or encrypted, the operating system stops loading, and in this case only a full format of the disk with reinstallation of the OS helps.

Computer viruses: types and their names in the main classes

Now let's move on to a more extended classification. The main computer viruses in general are:

  • file viruses contained in an infected file and activated only when it is launched by itselfby the user or accessed by the system/program;
  • boot viruses that embed their own codes or startup commands into the autostart of the system or removable media;
  • macro viruses contained on websites on the Internet or sent by e-mail in the form of scripts that are executed exclusively in installed programs or add-ons;
  • network viruses.

Again, this distribution can also be called conditional, since today there are also mixed types of threats such as file-boot or network macro viruses.

Main types of computer viruses: names and impact descriptions

Finally, the most accurate description of threats can be found in the following classification:

  • Trojan applications that infiltrate computers under the guise of safe legal software that can access installed programs and user data, transfer computer control or "leak" information to intruders;
  • spyware stealing extremely sensitive confidential information or tracking user activity on a computer;
  • keyloggers related to spies that monitor keyboard input;
  • ransomware (winlockers) blocking the system and requiring money transfer for unlocking;
  • encryptors that completely encrypt user or system files of a certain type;
  • vandals seeking to cause maximum damage to the operating system in terms of loss of performance;
  • hybrid rootkits that simultaneously track actionsuser and interfering with the operation of the system according to a certain scenario;
  • botnets that turn a computer into a kind of zombie and use its resources to carry out DDoS attacks or influence other terminals via networks or the Internet.

In general, it is worth saying that these are only the main names of computer viruses, since they are replenished almost daily with more and more new instances that cannot be attributed to any of the known categories.

Functioning algorithms

Computer virus infection and its types have been sorted out a bit. However, we should dwell separately on the classification of threats in terms of the algorithms they use. For this, a division into resident and non-resident viruses has been adopted.

Resident and non-resident viruses
Resident and non-resident viruses

Resident threats are programs that load their executable components directly into RAM and can be constantly active from the moment the operating system is loaded until the computer is turned off. Non-resident threats usually have a limited duration of activity, although they can also load their small resident part into RAM, but usually this does not happen.

A vivid example of residents are all kinds of macro viruses in the form of executable scripts, and many of them also use ste alth technology, which allows them to remain unnoticed in the system, replacing the elements accessed by the operating system with their own processes.

One more distributionnames of computer viruses by class is associated with self-encryption and polymorphism. Encryption in some ways resembles ste alth camouflage, but polymorphic viruses are able to constantly change, which makes it very difficult to detect by protective means.

An example of a polymorphic virus code
An example of a polymorphic virus code

Some of these threats may not contain signatures of malicious code at all, according to which one could at least with some degree of probability classify them as viruses. But the most dangerous threats very often even use some non-standard methods of disguise, allowing them to hide deep in the kernel of the operating system, where no antivirus can reach.

Destructive properties of viruses

Despite their names, computer viruses of different classes are very similar to each other. But in order to classify them according to the degree of impact, it is customary to distinguish four categories:

  • harmless (prank programs);
  • non-dangerous (limited only by the consumption of system resources);
  • dangerous (resulting in very serious OS failures);
  • very dangerous (completely incapacitating the system or destroying data stored on the computer).

Basic methods of combating computer threats

Naturally, as the first method of detecting all kinds of known threats or initializing suspicious objects, it is recommended to use standard antiviruses that have at their disposal signature and behavioral analysis modules, as well as Anti-Ste alth modules.

Modern antiviruses
Modern antiviruses

Antiviruses look good in this respect too, with the ability to send suspicious objects for analysis to the "cloud" or "sandbox". But one cannot absolutely rely only on such tools.

Tips for removing some adware yourself

Advertising viruses, of which there have been a lot of lately, can be removed by yourself. As a rule, such threats are not particularly masked in the system, and you can find them either in the list of installed programs, or among panels or browser extensions.

Clearing the browser shortcut
Clearing the browser shortcut

To neutralize these threats, it is enough to uninstall the main application, clean the registry and residual files in Explorer, change the search engine and home page in browsers, and then finally correct the path to the browser launch executable file in the shortcut properties, removing all unnecessary links and postscripts after specifying its name with the extension. Not bad in terms of uninstallation, uninstallers help to automatically clean up leftovers.


That's briefly everything that concerns the names of computer viruses, their distribution into classes, groups and categories, based on various criteria. As additional recommendations, the following can be advised:

  • install only powerful antiviruses, even shareware (many of these programs can be permanently activated for 30 days or more using special free codes);
  • don't ignore warningsantiviruses when working with the Internet;
  • do not visit sites that are known to be questionable and do not download files from them;
  • carefully consider suggestions for installing additional software;
  • check the contents of removable media before doing anything with them;
  • do a preventive check at least once a month using portable utilities.

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