Hacker (----) virus attack and defense of viruses

In the Internet, computer viruses are programs that threaten the security of computers. For computer viruses, users not only need to master their basic knowledge, but also to understand the common virus and simple virus production methods. Whether the virus is based on viruses or simple viruses, users need to master the effective measures and professional software to protect against viruses.

Computer virus is not caused by sudden or accidental factors, it is a program written by man. Computer viruses can disrupt the functionality or data of computers, affect the use of computers, and replicate themselves . To fully understand the virus, you need to understand the classification of viruses, characteristics, transmission pathways and computer poisoning after the common symptoms.

I. Classification of viruses

There are countless computer viruses in the Internet, and their classifications do not have a fixed standard, and the same virus may belong to different types according to different classification criteria. Common classification criteria: classified by operating system , by Media classification, by link or by virus destruction .

1, by operating system classification

Can be divided into: Windows system virus, Unix/linux virus two kinds.

1) Windows system virus: This type of virus is also known as Windows virus. Because of the widespread use of Windows systems, the system became the main object of computer virus attacks. In addition to viruses that infect files, Windows virus also has a variety of macro viruses, including viruses that infect Office files. One of the concept virus is a more famous Word macro virus .

2) unix/linux virus: UNIX and Linux used to be a virus-free operating system, with the development of computer viruses, virus targets began to target Unix and Linux. The Bliss virus is a well-known virus that attacks Linux systems, followed by a cross-platform Win32.winux virus. It can infect both PE files in Windows systems and elf files in Linux systems .

Tips: Attacking viruses from other systems

In addition to the two common viruses, there are viruses that attack other operating systems. such as attacking the Mac OS system of the Macmag virus, attacking the smartphone operating system of the Vbs.timofonica virus, etc.

2. Classification by media

Can be divided into single-machine virus and network virus two kinds.

1) stand-alone virus: This type of virus carrier is a disk that infects the operating system through a disk, and then infects other disks, removable devices, and so on, infecting other computers . Early computer viruses fall into this category.

2) network virus: The media is the Internet. With the increase of Internet users, the network virus spreads faster, the scope is wider, the harm is greater. Network viruses often cause network congestion, modify Web pages, or even combine with other viruses to modify or destroy files . such as GPI virus is the world's first special attack computer network virus, and CIH, Sircam, Code redxode Red H xode Blue, nimda.a and other viruses in the Internet more and more serious, has become the most harmful species of virus.

3, by Link form classification

Computer viruses must enter the system before they can infect and disrupt operations, so that computer viruses must be linked to files within the operating system that may be executed. These linked files can be either system files, applications, or data files (such as Word documents) that are used by your application. According to the computer virus to the link form of these files, can be divided into the implementation of file infection virus and operating system-type virus two.

1) Executable file infection virus: This kind of virus infects an executable program, link the virus code and the executable program, when executable program is executed, the virus will initiate with it.

2) Operating system virus: This kind of virus program uses its own logic to replace some of the legitimate program modules in the operating system, thus parasitic in the system partition . When you start your computer, the virus program is run first, and then you run the startup program, which is very destructive and can cause the system to fail to start or even paralyze.

Tips: source-based viruses

Source-type viruses are inserted into the source program before they are compiled in a high-level language, and become part of a legitimate program after compilation. This type of virus is generally parasitic in the compiler handler link sequence. The virus is not uncommon at present.

4, according to virus destruction situation classification

Viruses can be classified as benign and malignant viruses by virus destruction.

1) Benign virus: refers to those who express themselves, without destroying the system of the virus . Many of these viruses come from the hands of mischievous authors, who are not designed to destroy computer systems, but to show their skills and talents in programming. Although this type of virus is not destructive, they can affect the normal operation of the operating system and occupy computer resources .

2) Malignant virus: Compared to benign virus, the result of malignant virus is more serious. This kind of virus has the function that destroys the System Information resource . Some malicious viruses can delete data and files stored in the operating system ; some malicious viruses randomly write to the disk, the surface can not see the virus destruction traces, but the file and data content has been changed; there are some malignant viruses Format the entire disk or a specific sector so that the data in the disk disappears .

Ii. characteristics of the virus

Although there are many viruses in the Internet, and the classification is not uniform, but the characteristics can be broadly summarized as: destructive, contagious, covert, latent and non-predictable.

1. Destructive

After the computer suffers a virus invasion, may cause the normal program to be unable to run, the virus follows the built-in instruction to the computer inside the file to delete, the modification and so on, may even format the partition of the disk .

2. Contagious

The virus is not only destructive, but also contagious. infectious is a basic feature of computer virus, once the virus has been copied or produced variants, its propagation speed is very difficult to prevent.

3. Concealment

After the virus successfully invades the system, the target computer can still run normally, the infected program can run normally, the user will not feel obvious abnormality. Because the virus is automatically hidden in the system after it invades the system, the virus will not destroy the operating system or files according to instructions until it meets the trigger conditions set in advance .

4. Latent sex

The latent sex mainly manifests in two aspects:

First, if the user does not use professional testing procedures (often referred to as anti-virus software) can not detect the potential computer viruses in the system, so the virus in the system quietly stay for a few days, months, or even a few years, once the time is ripe, will continue to reproduce and spread;

Second, refers to the computer virus is preset a trigger mechanism, does not meet the trigger conditions, the computer virus in addition to the infection will not do any damage, once the departure conditions meet, it will cause great damage to the system.

5. Non-predictable

With the development of science and technology, virus production technology is also constantly improving, computer viruses always walk in front of anti-virus software . new operating system and application software, to provide new space for computer viruses, which makes the future of virus prediction more difficult , so users need to constantly improve the knowledge of computer viruses, while enhancing the protection of virus awareness.

Tips: Capturing system control

Computer viruses successfully invade the target computer, usually take control of the operating system, so as to achieve the purpose of infection and damage system. Anti-virus technology is to seize this feature, to seize the virus before the control of the system, so as to prevent computer viruses to seize.

　　

　　

　　

　　

　　

Hacker (----) virus attack and defense of viruses