The virus is a program that may disturb the normal working of a computer without that knowledge or permission of a user. The viruses attached itself to the files in flash drives, hard drives, and email attachments. A file containing viruses is called infected file. The virus is activated when the infected file is executed.
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Following are the important types of virus:
1. Boot Sector Virus:
A disk is divided into tracks and sector. The disk that contains operating system has a special program in its first sector. This sector is known as the boot sector. The program in boot automatically loaded into memory when the computer starts. The program loads operating system in the memory.
The Boot Sector viruses modify the program in the boot sector. It loaded into memory when the computer is turned on. The viruses are attached with the executable file like .exe, .com and .dll files. When the user use uses these files, the viruses attached with these files is activated. It infects other files and performs destructive commands and destroys data files.
2. Chernobyl Virus:
The famous Chernobyl virus deletes all Microsoft Office files. It also deletes the partition information from disk and causes huge loss of data.
3. Logic Bomb:
A logic bomb is also called time bomb. It differs from other viruses. It is activated at certain date and time. Michelangelo is an important logic bomb, is damage data on hard disk on March 06.
4. Trojan Horse:
Trojan Horse hides as a useful program. It contains hidden instructions to erase data or cause other damage. It executes illegal, destructive instruction in the middle of a program such a computer game. FormatC is an example of Trojan Horse.
Redlof is a polymorphic virus and written in Visual Basic Script. It relies on Microsoft ActiveX Component to execute itself. It locates Folders.htt and infect that file. Folders.htt is a part of Microsoft Windows Active Desktop Feature.
How Does Virus Spread?
It spread on different devices due to following reasons:
The viruses are most commonly spread through emails. An email may contain an infected file attachment. It can spread if the user opens and downloads an email with an infected file.
Viruses can spread if a user connects to the network that contains a virus. The Internet is an example of such network. When a user downloads a file infected with the virus from Internet, the viruses is copied to the computer. It may damage the files stored on your PC.
3. Removable Storage Media:
4. Pirated Software:
The illegal copy of the software is called pirated software. The virus can spread if user installs pirated software. A variety of pirated software is available in CD’s and from the Internet. Some software companies intentionally add virus in the software. It is automatically activated if the user uses the software without purchasing a license.
When the virus starts working, it is called the activation of a virus. It normally runs all the time on the computer. Different viruses are activated in different ways. Many are activated on a certain date. For Example, a popular virus Friday the 13th virus is activated only if the date 13 and day is Friday.
- It can delete some or all files on the device. It may also format the hard drive.
- Some viruses make unnoticeable changes.
- They corrupt data and make it unusable.
- A virus may detect some private information like passwords or credit card information. It may send data to some other users on the network.
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The virus infects a computer if Antivirus is not installed. Latest Antivirus software should install on the device to defend viruses. Your device can be protected by following precautions:
- The latest Antivirus should be installed on your device.
- The Antivirus software must be updated regularly.
- Scan removable devices such as USB, Floppy disks, and CDs before use.
- Junk or unknown emails should not be opened.
- Unauthorized or pirated software should not be installed on your device.
- Periodic Backup of data should be taken regularly.
- Freeware and shareware software from the Internet normally contain viruses. It is important to check software before using them.
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A type of software that is used to detect and remove viruses is called Antivirus Software. It contains information about viruses. They can detect and remove them.
Many Antivirus programs are available on the Internet and in the Markets. Some software can’t detect and remove viruses because many new viruses invented and spread through the Internet. Antiviruses program also upgraded continuously to remove these new kinds of viruses. By upgrading antivirus you not only detects viruses from devices but also prevent from entering into the device.
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Some Popular and Important Antivirus programs are:
Some important advantages of using Antivirus are as follow:
- Antivirus program protects important data.
- It checks all files before entering in the device.
- It alerts the user if any virus is detected.