1 What is a computer virus:
A computer virus is a program that can replicate itself and spread from one infected computer to another. The objects can be infected with the system, program, or document files. After infecting a computer, it is possible to slow down the damage to the contents of the infected files, lose data or switch to the normal operation of computer systems.
The virus can also use your computer to distribute illegal advertisements and send spam emails that take advantage of security (adware), steal personal information such as bank account number, credit card number, etc. (spyware). Some types of viruses can use a computer to create a bot net (Virtual Network Computer) server to attack other systems, websites, etc.
Type 2 viruses for Windows-based computers:
Van many computer viruses that prevent the functioning of the computer. Here are some of the different types of viruses:
Trojan: This file is created by the e-mail viruses attached to e-mail. If you are open, you can scour the hard drive of your personal and financial information, such as social security, account and PIN numbers. Once collected the info, you can send over the Internet by a hacker or thief.
Macro Virus: This is a computer virus that infects the Visual Basic language documents for applications, such as Microsoft Word, Microsoft Excel, etc. This type of virus can cause damage (such as removing the data on your hard drive, for example).
Worms: This is a program that can self-replicate itself. It can be moved from one computer to another and replicate itself in the computer system and then spread to hundreds of copies to other computers, which can cause widespread damage.
Rootkit Virus: This is a program that can cover the processes, files and registry data to your computer (a database that is used to save the Windows and program settings). Rootkit is usually to hide the activities and processes of viruses that can damage your computer. Promote a hacker to control the system.
bootsector Virus: A virus that can hold up to the first part of the hard disk to read the computer's boot time. They are usually covers floppy disks.
Logic Bombs: This is a program that can send data to many of the same e-mail address and overwhelm the system, or block the connection to the server. It is also used to threaten the other (for example, mail bombs, etc).
memory-resident viruses: This type of virus to the RAM. From there, you can overcome and interrupt the operation of the supply system. It can corrupt files and programs that are open, closed, copy, rename, etc.
multipartite virus: These viruses are spread in different ways. This can vary in its action, depending on where the installation, and the presence of certain files.
3- How to get a virus and prevention:
These are three common ways that your computer can get infected by viruses:
E-mail: e-mail to get the a person with one or more viruses. If the attachment is opened the virus to infect the files on your computer. Viruses can also send emails to people's email address books, or e-mail folder automatically. So, do not open unknown email attachments, or they are not after you open an antivirus.
Internet: If you download an exe file or a data file from the Internet or other public networks, viruses may be transferred to the computer. Sometimes the free software on the internet viruses, especially if the download sources such as Torrent or Usenet news groups. Therefore, if necessary, you should download the files from reliable sources.
Peripherals: The devices such as MP3 players, USB flash drive, memory card or CD Rom is also spread viruses. So remember to scan for them after they have been connected to the computer.
4- symptoms of virus infection
These are some of the symptoms that indicate virus activity
• the computer unusual activity (such as programs to crash a lot or slow rotating) .
• Messages and images (not the current job) comes unexpectedly.
• The program starts up unexpectedly.
• Firewall information about a particular application tries to connect to the Internet (independent of what works).
• friends say they receive an e-mail, but you did not send them.
• get lots of system error notifications. (Note: This can also come from another activity, such as hardware problems, system failure or true)
• Windows is not running when you start the computer. (Note: This can also come from hard disk failure)
• You realize that the folders and files are removed or changed.
• It finds that there is an access to the hard drive (one of the small flashing lights), although there are no programs running.
• abnormal signals to the browser, for example, opens an unfamiliar website or close your browser tabs.
• Advertisement pages pop up, change your desktop wallpaper.
• occur .exe files and folders with the same name.
• the right corner of the computer, there is a small sign posted "your computer is infected" or "Virus Alert" etc.
• If you open a USB thumb drive, unknown files like Autorun inf, New Folder.exe etc. will be displayed.
• do not press Ctrl + Alt + Delete (Task Manager), and warned that the administrator has disabled it.
• Folder Options disappear.
• The computer continuously restarts when you try to shut down.
• You can not log on to your Windows account the appropriate login information.
5 Do's infected
• Make sure that your antivirus software to the latest update. If necessary, download the update on another computer, and update it manually.
• downloaded from the Internet or a local area network (LAN).
• If Windows is not running, start it in safe mode (if you turn on your computer, press F8 when the computer starts up, then select "Safe Mode" in the menu).
• Run a full scan Anti-Virus.
• If your computer is infected enough, but you have important files and documents on it, do a full virus scan with updated antivirus software. If you find a virus, then delete all of them open to additional disk (USB, thumb drive, etc.) and search for autorun.inf file and remove them. Then restart the computer.
• If you have any difficulty in finding a way to remove the bad software, read the Internet Security Software Vendor in search of a core of dedicated tools to remove them.
• If you find a bad program, follow the instructions for Internet Security Software Supplier. Good Security software provides options such as blocks infected files, isolating potentially infected files, worms and Trojan removal.
• If there are no important files from computer disks, format the disk and reinstall Windows and your applications. That's pretty extreme and lengthy process, and it is recommended to backup before starting the machine settings. When you're done, do not open any ancillary storage devices (USB memory sticks, etc.) have installed antivirus software, do a full scan, you can find Autorun.inf files and remove them. Restart the computer after.
• If your antivirus software does not find anything, your computer might not be infected. Check the hardware and software installed on your computer meets the hardware specifications of the operating system. Delete unnecessary or unwanted programs to save resources and ensure that you have updated your Windows operating system via Windows Update.