Computer Viruses Types

What are Computer Viruses?

Computer viruses – a type of malicious software that can make copies of itself and implemented into the code of other programs, system memory, boot sectors, as well as distribute their copies on a variety of communication channels, with the aim of disrupting software and hardware, delete files, bring into disrepair accommodation structures data. Lock users 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 and begins to create copies of themselves, 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, may be noticeable because will consume system resources and data channels, resulting in 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 consist of violating the boot loader of the operating system, which leads to the impossibility of its work, or change the file table, which makes inaccessible certain files.
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 Windows, the 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 is in the file is activated when you access the file. File viruses – 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, because the infection does not stay in the same computer, or even a local area network and begins to spread on a variety of 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 a modification of 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 actions of the user, keeping information about his activities, the entered password, sites which you visit, etc.

Non-resident virus

Is an integral part of the infected program and can only function when program operating.

Most viruses really dangerous, that can destroy user data, documents, system areas, render useless the operating system or even the hardware components of the computer.

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 places of storage and data communications. 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 their modules under the program modules that are used to create files with similar names and parameters, as well as 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 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 own masking algorithms from scanning. Masked by spoofing malicious code on a useful during scanning, a temporary breeding functional modules of work in the case of 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 string 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 very dangerous 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, which could cause the simultaneous infection of a huge scale. An example of such a virus is a virus 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, as 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 computer viruses, we can help you get rid of them in the shortest time. Cure your computer, you can use our elaboration – Trojan Killer.

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