Part One - Viruses

The Viruses are most often small programs written for distribution and destruction of computer systems. The Viruses most often attach code to other files and thus infect them, make their copies and thus repeatable. The viruses most often infect executable files.

Types of viruses 
1. Polymorphic viruses - viruses that are extremely difficult to detect because they constantly change their code. It is known that no two identical code polymorphic viruses. Such a virus can make its thousands of modifications to protect th antivirus software. Each new copy of these viruses is encoded differently.
2. Macro viruses - that are among the most common viruses. This is because their creation is a breeze. Distribution is also supported by the fact that they are most commonly distributed with programs that are installed on each PC that is Microsoft Office.
3. Stealth viruses - these are the most dangerous viruses because they are made so that their discovery is really hard. - Some of these viruses infect the computer system and later spread to infect new systems. - Almost always code of stealth viruses is algorithmic locked by Da altered by any multiplication of the virus code. Most viruses are resident protection technique by which to protect themselves. - These viruses are extremely difficult to clean and detection in many cases forcing antivirus scan report that detected no viral infection. They showed no difference in file size and mark the sectors themselves in memory as mechanically damaged and thus their scan is skipped.
4. Resident viruses - when such a virus is loaded into the system remains r3ezidenten to shutdown. This is done through the functions of the operating system or BIOS-a. These viruses are very common and infect very many systems ..
5. File viruses - viruses that infect executable files or files with some information as the goal is to be loaded with the file itself and thereby gain access to the resources of the infected system.
6. Boot sector viruses - such viruses are activated when the system loader then read boot sector from external memory and execute it. When you try to access a conventional boot sector often apply stealth techniques and the operation was transferred to pre-preserved original boot record. Fall to boot and viruses of type Partition table (MBR) viruses. Distributed only in hard disks.


Virus programs:
1.Worm (worm) - as opposed to viruses, computer worms are malicious programs that replicate themselves from one system to another, instead of infecting files located in your computer. - Mass mailing email worm - worms themselves are sent to all email addresses they find on the infected system. - Internet worm known as "email worms are the most widely known modern worms and because of its method of distribution - through attachments.
2. Trojan (Trojan) - Trojan horse virus which is most often a virus that is disguised as a regular program activities as listening to music or watch a multimedia file, the virus is hidden inside. Thus, users hardly understand that they are infected with viruses.

Virus (Virus) A computer virus is a program that was created with the ability to replicate itself by infecting other files. When it comes to boot sector (boot sector) virus then infected boot sector of the operating system on a floppy disk or tvurdiya. Although the primary function that is certain viruses that multiply, most of them are dangerous because they contain code that breaks the information into the computer. The first computer virus was discovered in 1986 and since then the world have registered tens of thousands of virus. In most cases, only a small fraction of them are active and dangerous as contemporary antivirus programs largely protect consumers against new computer viruses, offering combined protection against Internet worms, viruses and Trojans.
Worm (Worm) Unlike viruses, computer worms are malicious programs that replicate themselves from one system to another, instead of infecting files located in your computer. For example, a worm that razporostranyava mass mail (mass-mailing email worm) send copies to all email addresses that you can find recorded in the infected computer. Network worm copies itself and spreads over the network, Internet worm spreads through Internet, etc.
Internet Worm (Internet Worm) Unlike viruses, worms do not infect other files. Instead, they are copied and distributed until completely discharge system resources on your computer. The most common and popular contemporary Internet worms worms are known as "email worm" because of its method of distribution - through attachments to emails sent to addresses taken from the Outlook Address Book or Outlook Express. To prevent this type of virus is necessary to never open attachments that you receive unexpectedly.
Trojan, Trojan (Trojan) The trojan is a program that installs to do something completely normal (eg to carry mp3 music), but actually doing something malicious (eg send numbers introduced credit cards gave a email address). Trojans are often used to obtain secret access to the system which are installed ie someone remotely control your computer. Trojans do not reproduce like viruses and do not spread as worms.
Macro Virus (Macro Virus) Macro viruses are written in programming languages (eg VisualBasic), supported by some products such as Microsoft Excel and Microsoft Word. Macros are small utilities that are included in a document to automatically perform certain actions for the user (eg, fast computation of a formula set values). Macro viruses are a common form of viral infection, which is exceeded only by Internet worms because of their easy distribution. As with any other virus, and macro viruses have a high risk of data loss. However, so far, Microsoft has introduced several forms of protection against unwanted execution of macros, this form of virus is widespread. Most often macro viruses infect a so-called "global template" (global template - as Normal.dot in Word), to be disseminated in any other documents on your computer.
Malware (Malware) Malicious code such as viruses, worms or Trojan horses are sometimes called "malware."
Polymorphic viruses (Polymorphic Virus) Polymorphic viruses change their code to avoid detection by antivirus programs. Polymorphic virus recode or change each time is recorded. This makes the possibility of very large variations.
Boot sector virus (Boot Sector Virus) Boot sector viruses are spread through infected floppy disks. This usually happens when users leave the disk in the floppy drive. When the system is started next time the computer tries to first boot from the floppy. If the disk is infected with boot sector virus, it will be recorded in the boot sector-and the hard disk. To protect your computer from boot sector viruses, you should change the settings in the CMOS so as to allow boot only from hard drive - C: \, but not from floppy - A: \.
Stealth (Stealth) Stealth viruses attempt to hide and can not be found. One method is to redirect calls made to the infected file. For example, the virus can stay in memory, and only when an application be made for writing on disk, it is activated.
File Viruses (File Viruses) File viruses infect executable files by inserting code in some parts of the original file so that code can be executed when someone is paid to the original file. In some cases, file viruses can label the whole file or delete the original and create a viral copy of the same name. File viruses always have as their purpose operating system (Windows, UNIX, Macintosh, DOS etc.).. Inscribing targets files resulting in total and irrevocable loss of original data.
Antivirus (Antivirus, Anti virus, Anti-virus) Antivirus or antivirus software is called a product which is used to detect malicious software code, protect computer system from infection and remove this code, if the infected system. Antivirus software is usually turned on by the producers themselves in independent tests to certify its quality and its ability to detect and remove viruses.
Disinfection (Disinfection) Cleaning, deleting or removing a virus called disinfection. In some cases disinfection can be achieved only by deleting the infected (infected) file. For example, a Trojan horse should always be deleted because it has no useful purpose and well-intentioned. On the other hand, a document that is infected with a macro virus should only be cleaned in order not to lose user data and utility macros. Although in most cases disinfection can be done without loss of valuable data, there is no guarantee that any file can be restored to its former condition. Therefore, antivirus experts recommend data recovery from pure backup copies. Anti-virus programs should rely only on the detection of viruses. However, if you saved up to date copy can restore a file by the antivirus program.
Heuristic (Heuristics) Heuristic scanning methods vary according to their manufacturer. Some companies argue that permit execution of certain actions of viruses in a secure and isolated environment. Other scanning every file opened or processed parts of malicious code. Heuristics are designed to detect unknown viruses before, so if viruses have recently written and distributed, the user still be protected. Heuristics are not 100% accurate and therefore recommends that users follow some basic rules of security for their computers are protected.
Blocking behavior (Behavior Blocking) Program behavior blocking monitors the actions of various files on your computer by preventing the operating system and related files from unwanted changes. Programs blocking behavior can monitor registry (registry) on Windows and warn the user if a program attempts to change it. So potrebitrelya may allow (for example, if you install new software) or to refuse to change (if any malicious program tries to save to your computer). Blocking behavior is a wonderful addition to other options to protect the operating system.
Check Integrity (Integrity Checker) Programs for checking the integrity scan and maintain a database of important information in the system or record critical system files. If a program tries to change any of these files, software for checking the 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 (Scanner) Scanners are products used to detect malicious code. They also protect the system from infection and remove any existing contamination. Typically, scanners check files for malicious code in real time when the computer starts or when users make a request for verification. Scanners, also relying on methods of checking the integrity or blocking behavior to protect the system from unwanted changes.
Attachment (Attachment) Attachment is such a file is added to forwarded e-mail (email). The use of attachments is very convenient and useful. All modern programs (clients) to support sending email attachments, usually button in the program contains an image of a paper clip. On the other hand, sending attachments is the primary method of distribution of much of today's viruses. Virus writers often ask interesting names of attachments, thus causing the curiosity of the recipient. When launching the attachment, the virus runs and infects the system.
Portable Executable File (Portable Executable) Portable executable (PE EXE) is a program that can run itself on any operating system Windows (Windows 95, 98, NT, 2000, XP, and ME). An example of this file notepad.exe (Notepad). PE EXE may have an extension other than. Exe, for example. Scr - screen saver.
Active X (ActiveX) ActiveX controls are feasible or OLE. OCX files. Example of OLE (Object Linking and Embedding) is as ActiveX controls "notebook" which mozheda be integrated into a spreadsheet or text document. ActiveX controls can be performed only in the middle of the operating system Windows, as for each version create different controls. Unlike Java applets that are loaded only in browsers, ActiveX controls have access to the operating system itself, which in some cases, lead to security problems.