Computer Virus
Computer virus are a destructive program that can replicate itlf and proliferation through the network, transmission. Virus code is very small, usually attached to other documents or procedures at the end, so they can easily hide in the system. Ability to lf-replicating virus on the network so that it can spread infection to other documents and procedures, once the virus spread to the network very difficult to track down.
In 1987, computer virus spread in the United States, and the first computer virus "small ball" at the end of the year spread to our country. Since then, has found a virus imported and domestic. So far, computer virus has rin to more than 20,000 kinds; which can attack more than 90% of micro-computer.
1. The characteristics of computer virus
bye bye 歌词(1) the basic characteristics of
(a) infection: a computer virus as a program that can replicate itlf to other normal procedures or systems of certain components, such as the disk part of the guide. This is the basic characteristic of the virus program. With the increasingly extensive network devel
opment, computer virus can be widely disminated through the network in a short time.
(b) latent: hidden in the infected system the virus does not immediately attack; the contrary, in its pre-attack, the need for a certain period of time or have certain conditions. Within the incubation period, it does not show any disruption of operations, making it difficult to find the virus and the virus can continue to spread. Once a virus outbreak, it can cau rious damage.
(c) can be triggered: Once certain conditions, the virus began to attack. This feature can be triggered is called. Take advantage of this characteristic, we can control its transmission range and frequency of attacks. Conditions may trigger the virus is the default date, time, file type or frequency of the computer to start.
(d) damage: the damage caud by computer virus are a wide range of - it not only undermines the computer system, delete files, change data, but also occupied system resources, such as disruption of the machine running. Its destruction of the designer's attempt to show.
(2) general characteristics
(a) Express Impact: In 1984, Dr. Fred Kordon allowed to u the UNIX operating system XAX11 / 750 computer for virus experiments. In a number of experiments, computer paralyze the average time is 30 minutes, the shortest period of time for 5 minutes. Typically, if the infected computer associated with the Internet, then the virus can be transmitted in a matter of hours thousands of computers.
(b) it is difficult to eliminate: On the one hand, day after day a new virus or its variants; the other hand, some virus may be eliminated in the resurgence of, for example, re-u when an infected floppy disk.
(c) vector characteristics: the spread of the virus can be ud as the normal vector information, thus avoiding the system we t up protective measures. In the normal operating system ur, the virus stealthily control system. Urs may also consider him the system is running normal.
(d) it is difficult to detect: the virus through a variety of ways beyond our control infection, in addition, with the illegal copying and the popularity of pirated software, virus detection
more difficult.
(e) to deceive the characteristics of: virus often hide themlves to avoid being detected.
2. The structure of computer virus
Computer virus usually five components - infection Fu, transmission modules, damage module, trigger module and main control module.
(1) infection at
Infection Fu, also known as virus signatures, a number of figures or characters from the ASCII coding constitute. When the normal procedure of transmission of the virus when it left in the program as a virus infection at the signature. Virus infection in a program intended to, it first checks whether there is any infection site; If so, the procedure has been infected, the virus will not spread it further, and if not, on the transmission of it. The majority follow this one-time transmission of the virus. If the virus does not check the site of infection, it may happen repeatedly transmitted, the length of the program would continue to increa, this situation is rare.
(2) transmission module
This is the transmission module boarding procedures. It completed three tasks: ① arch executable file or document coverage, 健身培训机构② to check whether the document has infected Fu, ③ transmitted it - if not found to be infected with FU, on the person boarding procedures Writing virus code.
original是什么意思(3) damage module环球雅思留学
It is responsible for the designers of the destruction in accordance with the virus code in an attempt to undermine the implementation of mission, including delete files, delete data, formatted floppy disk and hard disk, reducing the efficiency and reduce the u of computer space.
(4) trigger module
Its mission is to check whether the trigger conditions (for example, the date, time, resources, and transmission time, interrupt call, start number, etc.). If the conditions are ripe, it return "true" value, and damage mediator module damage, otherwi it return "fal" value.
(5) the main control module
raiderIts control of the four modules. In addition, it has procedures to ensure that the infected can continue to work correctly, the accident would not crash happened.
3. Computer Virus Classification
(1) by the parasitic Category
By parasitic, computer virus can be divided into lead-virus, file virus and mixed virus. * Boot virus: parasites in the disk guide means tho parts of a computer virus. It is a common virus, the u of computer systems do not usually check the guide part of the content is correct weakness, and retained in memory and monitor system operation, one has the opportunity to infection and destruction. According to the location of parasites in the disk, it can further be divided into the Master Boot Record boot record virus and paragraph virus. The former master boot hard drive transmission parts, such as "marijuana" virus, "2708" virus, "porch" virus; Record paragraph of transmission of the virus commonly ud hard drive Record paragraphs, such as "small ball" virus, "Girl" virus.
(2) by the conquences of classification
From the conquences of watch, computer virus can be divided into "benign" virus and "vicious" virus. "Benign" virus would destroy data or programs, but it will not make computer systems paralyzed. Initiator of the virus are most mischievous hackers - they created the virus is not in order to undermine the system, but in order to show off their technical capacity; Some hackers u the virus to disminate their political thought and ideas, such as "small ball" virus and "Ambulance car "virus. "Vicious" virus would destroy data and systems, resulting in paralysis of the entire computer, such as the CHI virus, "Porch" virus. Once the virus attack, the conquences will be irreparable.英语课件ppt
It should be noted that "dangerous" are a common feature of computer virus. "Benign" virus are not dangerous, but the risk of the conquences of relatively light. "Virtuous" is a relative concept. In fact, all computer virus are malignant.
4. Computer virus detection, elimination and prevention
(1) computer virus detection
At prent, caud by computer virus in software and hardware failures cau increasi
ngly rious damage. Most failures happen with the virus. In the computer by the computer virus infection or virus attack, there will be anomalies. Through the obrvation of the anomalies, you can determine the computer whether the initial infection of computer virus. The following anomalies may indicate that the computer virus has infected your computer:
* Procedures for loading longer than usual.
* The size of executable files change.
* Visit to the hard drive longer.班车英文
* Print slowly.
* Screen some strange characters and unusual display.
* Some system failures, such as the system can not access the hard disk.
* The actual memory size significantly smaller.
* Abnormal death.
* Program and data mysteriously disappeared.
* Abnormal sound from loudspeakers.
(2) the elimination of computer virus
(a) the principle of the elimination of the virus
毕业舞会* Prior to the elimination of the virus, backup all important data to prevent loss.
* U clean (no virus) the system disk to guide the computer, thereby ensuring that the virus program to kill virus-free environment in the run, otherwi the virus will again have disinfection of infected documents.
* To retain the guidance system of the order in the system will not boot recovery.
* Be careful when operating. Repeatedly to check read and write data until the beginning of the operation did not find any errors.
马赫是什么单位(b) how to eliminate computer virus?
At prent, in order to eliminate computer virus, artificial methods or tools can be ud; but most u the latter method.
If it is found that part of the hard disk boot record has been destroyed, can be ud to restore the correct boot record it. If any documents are found to be infected, u the normal document covering the same name it, or delete the file. All of the are artificial.
(c) the prevention of computer virus
First, we must rely on the law and the fight against computer virus. Law must be clear that the deliberate creation and dismination of computer virus is a crime. China has promulgated and implemented for the protection of information system curity requirements. This reflects the work of computer curity has embarked on the legal system. Each person should attach importance to computer curity issues. Secondly, we need to develop regulations and the implementation of management measures will be "prevention" as the fight against computer virus transplantation "major measures." Specific measures include the following:
* The u of an important ctor of the computer should be "special plane", with external isolation;
* Do not u a source of unknown or unclear whether the infected floppy disks and CD-ROM;
* Ud with caution and common utility software;
* Contains important data in the floppy disk t "write-protected." Writing when the person,
the temporary elimination of protection, write protection, after re-tting.
* Regular inspection of computer systems and regular backup procedures;
* U the hard disk boot. If you u a floppy disk, first of all virus-free floppy disk verification;
* Do not hesitate to lend to others floppy disk. If you have to lend, should first make a backup disk, and also to re-format the disk;
* When buying a new CD-ROM or floppy disk, u the former should first check the virus; * upgrade to the computer equipped with the latest anti-virus software;
* If possible, install on your computer anti-virus software;
* Strictly forbidden to play games on the computer, becau the virus often parasitic in the game software;
* Internet-linked computer online or offline should have anti-virus system (firewall);
* When you discover new virus, timely reporting to the local computer curity departments.
Anti-virus software tools can automatically prevent, detect and eliminate computer viru
commissions
s. U anti-virus tool is a speedy, efficient and accurate method. At prent, there are many excellent
Anti-virus software tools, such as the KILL 2000, KV300, AV95, etc. and Rising. U anti-virus software should upgrade to the latest version, becau new virus are emerging. Computer virus and anti-struggle between a computer virus will continue.
