Computer Viruses Types

What are Computer Viruses?

Computer viruses – a type of malicious software that can make copies of itself and implement into the code of other programs, system memory, boot sectors, as well as distribute their copies on a variety of communication channels, to disrupt software and hardware, delete files, bring into disrepair accommodation structures data. Lock user’s work or the destruction of computer hardware systems.



Computer viruses may exist in the system at various stages of functioning:

  1. The latent stage. At this stage, the virus code is in the system, but no action is taken, for the user will not notice. It can be calculated by scanning the file system and the files.
  2. Incubation stage. At this stage, the virus code is activated. It begins to create copies of itself, spreading them on the computer’s storage devices, local and wide-area computer networks, in the form of e-mail messages, and so on. For the user, it may be noticeable because it will consume system resources and data channels. The computer may run slower, downloading information from the Internet, mail, and other data may be slowed down.
  3. The active stage. At this stage, the virus continues to multiply its code in ways that are available to him, begins to destructive actions have targeted. Noticeable to the user because the main function of the virus to emerge – missing files, disable services, disrupted the functioning of the network, there is damage to the equipment.

Today, there are a lot of computer viruses. Every day appears thousands of new. However, all this defies classification.

By habitat, computer viruses can be divided into these types:

Boot viruses get into the boot sector of data storage devices (hard drives, floppy disks, portable storage devices). When you load the operating system from an infected disk, the virus is activated. His actions may violate the operating system’s boot loader, which leads to the impossibility of its work or changing the file table, which makes certain files inaccessible.
File viruses are often embedded in the executive program modules (files with the help of which made the launch of a program) that allows them to be activated at the time of starting the program, virus affect its functionality. Less common, file viruses, registry files, script files, driver files. An implementation may be conducted either by changing the code of the attached file or creating a modified copy. Thus, the virus in the file is activated when you access the file: file viruses are the most common type of computer viruses.
Multipartite virus combines features of two previous groups, enabling them to present a serious threat to your computer.
Network viruses spread through the network services and protocols. Such as sending mail, access files via FTP, accessing files through the local area network service. What makes them very dangerous is that the infection does not stay in the same computer or even a local area network and begins to spread on various communication channels.
Document viruses (often called macro viruses) infect files modern office systems (Microsoft Office, Open Office …) through the use of macros in these systems. Macros – a pre-defined set of actions, the firmware embedded in the document, and directly from modifying this document or other functions. Exactly the macros purpose of the macro viruses.

By the method of the existence in the computer environment viruses are divided into types:

Resident virus

Having caused by launching an infected program remains in memory even after its completion. He can create additional processes in memory, wasting resources. It can infect other programs run by distorting their functionality. Can “watching” the user’s actions, keeping information about his activities, the entered password, sites you visit, etc.

Non-resident virus

It is an integral part of the infected program and can only function when the program operates.

Most viruses are hazardous and can destroy user data, documents, system areas and render the operating system or even the computer’s hardware components.

According to the principle of operation, the viruses can be divided into several types:

  1. Parasitic – viruses, working with program files, partly exempting them from the system. They can be easily identified and destroyed. However, often file that was carrier considered unsuitable.
  2. Worm – viruses whose main task as quickly as possible propagate in all possible storage and data communications places. Often they do not take any destructive action. There is transportation for other types of malicious code.
  3. Trojans – received its name in honor of the “Trojan horse” because they have a similar principle. This type of virus disguises its modules under the program modules used to create files with similar names and parameters and replace the registry entries, changing the reference program modules working on their own, called by the virus. Destructive actions are reduced to the destruction of user data, send spam, and tracking user activity. They multiply themselves often can not. Identify them is quite difficult, as simply scanning the file system is not enough.
  4. Viruses Invisible (Stealth) – named for the aircraft invisible “stealth”, the most difficult to detect because they have their own masking algorithms from scanning. Masked by spoofing malicious code during scanning, a temporary breeding functional modules of work in the scanning process, concealment of its processes in the memory, etc.
  5. Encrypted viruses – viruses, which malicious code is stored and distributed in an encrypted form that allows them to be not available for most scanners.
  6. Matting viruses – viruses do not have a permanent signature. Such a virus is constantly changing code strings in the operation and reproduction. Thus, it becomes invulnerable for simple virus scanning. To detect them, it is necessary to apply the heuristic analysis.
  7. “Rest” viruses – are hazardous because they can very long time in a state of dormancy, spreading across computer networks. Activation of the virus occurs when certain conditions, often at a certain date, could cause the simultaneous infection of a huge scale. An example of such a virus is CHIH or Chernobyl, which was activated on the anniversary of the Chernobyl accident. He caused the failure of thousands of computers.

Thus, a computer virus can be a major threat to the home user and the computer network of a large company. To avoid such threats, the engineers of our company carried out many operations that reduce the chance of infecting your computer or network to a minimum. If your computer is already infected with computer viruses, we can help you get rid of them in the shortest time. Cure your computer, you can use our elaboration – Trojan Remover.