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The computer virus

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Computer virus is a program that has created the opportunity to multiply itself by other infected files. When it comes to buut sector (boot sector) virus then infected boot sector of the operating system on floppy or hard disk. Although the main function which is determined viruses that multiply, most of them are dangerous, because code that damaging information on the computer. The first computer virus was discovered in 1986 and since then until now in the world have registered tens of thousands of virus. In most cases, only a small proportion of them are active and dangerous as contemporary antivirus programs largely prevent new users from computer viruses, offering protection from a combined Internet worms, viruses and Trojan horses.


Unlike viruses, computer worms are malicious programs that copy themselves from one system in another, instead of infected files in your computer. For example, worm, which is widely spreading by mail (mass-mailing email worm) send copies to all e-mail addresses that you saved to open the infected computer. Network worm is copied and distributed network, Internet worm spreads via the Internet, etc.

Internet Worm

Unlike viruses, worms do not infect other files. Instead, they are copied and distributed until completely exhausted system resources on your computer. The most widely known modern worms and web worms are known as "email worm" because of its method of distribution - through attachments to the letters sent to addresses taken from the address books in Outlook or Outlook Express. To prevent this type of virus is necessary never to open attachments that you receive unexpectedly.

Trojan horse

Troyan horse program that installs to do something completely normal (eg, mp3 music to perform, but actually doing something malicious (eg send numbers entered credit card nadaden email address). Troyantsite are often used to obtain secret access to the system, which installed a remote that can control your computer. Trojan horses do not breed like viruses and are not spread as worms.

Macro Virus

Macro viruses are written in programming languages (eg VisualBasic, which is supported by some products such as Microsoft Excel and Microsoft Word. macros are small program that are included in a document to automatically perform certain actions for the user (eg a quick calculation on the formula set values). Macro viruses are a common form of viral infection, which is surpassed only by the Internet worm, because of their easy distribution. As with any virus, macro viruses and when there is a great danger of losing data. However, so far Microsoft has introduced several forms of protection against unwanted execution of macros, this form of virus is widely spread. The most common macro viruses infect a so-called "global template" (global template - example in Word, to spread in all other documents computer.


Deceptive code like viruses, worms or Trojan horses are sometimes called "malware".

Polymorphic Virus

Polymorphic viruses change their code to avoid detection by antivirus programs. polymorphic virus is prekodira or change each time is recorded. This makes the possibility of occurrence of very large variations.

Boot Sector Virus

Boot sector viruses are spread through infected floppy disks. This usually happens when the user left disk in floppy drive. When the system is started next time the computer tries to load the first of floppy. If the disk is infected with boot sector virus, it will be recorded in the boot sector-a hard disk. To protect your computer from boot sector viruses, you can change the settings in the CMOS so that it allows loading the operating system only by hard drive - C:, but not by floppy - A:.

Stealth Virus

Stealth viruses attempt to hide and can not be found. One of the methods of this shift is the call made to the infected file. For example, the virus can remain in memory only when a request to write to disk, it is activated.

File Viruses

File viruses infect executable files by inserting a code in some parts of the original files so that code can be executed when someone is paid to the original file. In some cases, file viruses can nadpishat whole file or delete the original and copy to create a virus with the same name. file viruses always have as their object operating system (Windows, UNIX, Macintosh, DOS, etc.).. captions files goals and leads to complete loss nevazvratima original data.

Antivirus, Anti virus, Anti-virus

Antivirus or anti-virus software product is called, which is used to detect malicious software code that protects the computer system from infection and remove such code if the system is infected. antivirus software is usually included by producers themselves, in independent tests that certify the quality and ability to detect and remove viruses.


Cleaning, deleting or removing a virus is called disinfection. In some cases disinfection can be achieved only through Remove contaminated (infected) file. For example, a Trojan horse should always be removed as it no good and useful purpose. On the other hand, a document that is infected with a macro virus should only be cleaned to not lose user data and utility macros. Although in most cases disinfection can be carried out without loss of valuable data, there is no guarantee that any file can be restored to its previous condition. For this reason, experts recommend antiviral recovery Data from pure backup copy. antivirus programs should be made only to detect viruses. If you do not have a recent saved copy you can restore a file by the antivirus program.


Heuristic scanning methods vary according to their manufacturer. Some companies argue that permit execution of certain actions of viruses in protected and isolated environment. Other scan every file open or cultivated in parts of the malicious code. heuristic methods are designed to discover previously unknown viruses, so if the viruses are quickly written and distributed, the user still be protected. heuristic methods are not 100 percent success rate and is therefore recommended that consumers observe some basic safety rules to protect their computers.

Behavior Blocking

Program monitors conduct in blocking the action of various files on your computer, such as to prevent the operating system and related files from unwanted changes. Programs crash in behavior may occur registers (registry) on Windows and warn the user if a program attempt to change it. potrebitrelya This may allow (for example, installing new software) or to refuse to change (if a malicious program tries to write on the computer). blocker behavior is a great addition to other options to protect the operating system.

Integrity Checker

Programs for checking the integrity scan and maintain a database of important information stored in the system or critical system files. If a program attempts to modify any of these files, software verification integrity, will notify the user and will ask for consent. Programs for checking the integrity, can help a lot in protecting your computer system, but they require a higher level of knowledge in the field of viruses and computer software.

Antivirus Scanner

Scanners are products used to detect malicious code. They also protect the system from contamination and remove any existing infections. Generally, scanners check files for malicious code in real time when you start the computer or when the user made a request for verification. Scanners, also rely on methods for verifying the integrity or blocking in conduct to protect the system from unwanted changes.


Attachment is a file that is added to email (email). The use of attachments is very convenient and useful. All modern programs (clients) for e-mail can send attachments, such as simple button in the program contains image of the paper clip. On the other hand, the sending of attachments is the main method of distribution of most modern viruses. virus authors often ask interesting names attachments thus provoke curiosity of the recipient. When you start attachment , the virus is executed and the infected system.

Portable Executable

Mobile executable files (PE EXE) is a program that can start itself each operating system Windows (Windows 95, 98, NT, 2000, XP, and ME). Examples of such file notepad.exe (Notepad) . PE EXE extension may be different from. exe, for example. scr - screen saver.


ActiveX controls are executable or OLE. OCX files. Example of OLE (Object Linking and Embedding) is the ActiveX control as "notebook" which mozheda be integrated in a spreadsheet or text document. ActiveX controls can to be implemented in mid operatsionata system Windows, as each version create different controls. Unlike Java applets that are downloaded only browsers, ActiveX controls have access to the operating system itself, which in some cases leads to safety problems.


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