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Virus classification

According to the properties of computer virus category: Media
1, virus/> under media of viruses, viruses can be divided into network viruses, file viruses, boot viruses.
network virus through computer network spread infection network in the of executable file, file virus infection computer in the of file (as: COM,EXE,DOC,), guide type virus infection started fan district (Boot) and hard disk of system guide fan district (MBR), also has this three species situation of mixed type, for example: more type virus (file and guide type) infection file and guide fan district two species target, such of virus usually are has complex of algorithm, they using non-General of approach invaded system, Both encryption and deformation.
2, the ability to destroy
according to viruses can be divided into the following types:
-harmless: reduces the available disk space in addition to the transmission, no other effect on the system.
risk-free: this type of virus is only reduced memory, display images, sounds or similar sound.
danger: this virus cause serious errors in computer systems operations.
very dangerous type: this type of virus removal program, destroying data, clear the memory area of the system and important information in the operating system.
these viruses cause harm to the system, not the algorithm itself there is a danger in calling, but when they infect can cause unexpected and catastrophic damage. Caused by a virus and other program errors can damage files and sectors, which are divided according to the damage they caused. Some harmless virus may now be on a new version of DOS, Windows, and other operating system damage. For example: in the early days of viruses, there is a "Denzuk" virus very good work on 360K disk, it will not cause any damage, but later in the high density floppy disk can cause massive data loss.

3, virus-specific algorithms based on virus-specific algorithm, viruses can be divided into:
with viruses: this kind of virus does not change the file itself, which according to the algorithm generated EXE file with, has the same name and different extensions (COM), such as XCOPY.EXE with the body is XCOPY.COM. Virus writing COM file does not change the EXE file itself, when DOS loads the file, along with priority is executed, then loaded by along with the original EXE file.
"worm" virus: transmission through computer networks, does not change the files and information using network memory from one machine to other machine memory, calculate network addresses, the virus itself is sent over the network. Sometimes they exist in the system, does not take up other resources besides memory.
parasitic viruses: in addition to accompanying and "worms" style, other viruses are called parasitic viruses attached to the boot sector of the system or in a file, transmitted through system functions, according to the algorithm is divided into:
practice virus: virus itself contains an error and cannot be well spread, such as some viruses in the commissioning phase.
of the mysterious virus: generally do not directly modify DOS interrupts and sector data, but through the equipment technology and file buffers, DOS Interior modifications, not easy to see resources, using more advanced technology. Using the DOS idle data area.
Variant virus (also known as the phantom virus): this virus uses a complex algorithm to make you spread each one with different content and length. Their general approach is a mix of unrelated to the instruction decoding algorithm and change the virus body.
malicious virus "four family"
a, and macro virus
due to Microsoft of Office series Office software and Windows system accounted for has most of PC software market, plus Windows and Office provides has macro virus prepared and run by required of library (to VB Library mainly) support and spread opportunities, so macro virus is most easy prepared and spread of virus one of, is has representative.
macro virus outbreak mode: when the document is opened in Word virus, macros can take over your computer, and then their infection to other documents, or delete files and so on. Word macro storage and other styles in the template, so the virus always put the document into a template and then store them in a macro. This results in some versions of Word will force you to infected document is stored in a template.
to determine whether the infected: macro virus attack
no signs of special, usually disguised as other dialog box lets you confirm. Machines infected with a macro virus, appears cannot print files, Office documents cannot be saved or saved as, and so on.
macro virus damage: delete files on your hard disk; private files to the public; sending files from the hard disk to the specified E-mail, FTP address.
precautions: usually better not several people share an Office program, to load a real-time virus protection. Virus variants can be attached in the message attached, and implementation when users open or preview the message, should be aware of. Anti-virus software can remove macro viruses.
CIH/> second, the CIH virus was the most famous and one of the most destructive viruses, it is the first virus that can damage the hardware.
damage: mainly by tampering with the data in the motherboard BIOS, causing computers to turn on a black screen, so that users cannot make any data salvage and removal operations. Variants of the CIH can by bundling other programs on the network or email attachment dissemination, and often delete files on your hard disk and destroying the hard disk partition table. So after the attack of CIH, even if you change the motherboard or other computer system without the correct partition table backup, exposure data especially the c partition on the hard drive of little chance to recover.
precautions: there are already many CIH immunization program was born, including virus maker himself wrote the immunization schedule. General running the immunization schedule may defy CIH. If you have been poisoned, but not attack, remember to back up your hard disk partition table and boot sector data for killing to avoid antivirus failed hard disk cannot be bootstrapped.
three, worms
the worm to copy itself as much as possible (worm-like breed) named, many infected computers and consume system and network resources, PC and server overload caused panic, and clutter the data within the system as the main failure mode. It does not delete your data immediately let you discover, such as the love bug virus and the Nimda virus.
four, Trojan virus
Trojan virus from ancient Greece Trojan war "Trojan horse" and named, as the name suggests is a kind of disguised latent viruses, bide and others.
modes of transmission: issued through e-mail attachments; tied up in other programs.
virus characteristics: modify the registry, resident memory, install backdoors on your system, boot load the included Trojans. Destructive
Trojan virus: Trojan virus attack to run client programs on the user's machine, once the attack, it can be a back door, regularly sends the user's privacy to the Trojans to the specified address, ports and built-in access to the user's computer, and any control of this computer, to file illegal operations such as delete, copy, change the password.