Virus infects computer system if antivirus software is not installed. Latest antivirus software should be installed on computer to protect it from viruses. A computer system can be protected from viruses by following these precautions:
1. The latest anti-virus should be installed on computer.
2. The antivirus software must be upgraded regularly.
3. The floppy disk should be scanned fro viruses before use.
4. Junk or unknown emails should not be opened.
5. Unauthorized or pirated software should not be installed on computer.
6. An important way of protection against virus is the use of backup of data. The backup is used if the virus deletes data or modifies it.
7. Freeware and shareware software from the internet normally contain viruses. It is important to check the software before using them.
Discuss different types of viruses.
Following are some important types of viruses:
1. Boot Sector Virus
A disk is divided into tracks and sectors. The disk that contains operating system has a special program in its first sector. The sector is known as boot sector. The program in boot sector is automatically loaded in memory when computer starts. The program then loads operating system in the memory.
The boot sector virus modifies the program in the boot sector. It is loaded into memory whenever computer is turned on. The virus is attached with the executable files like .exe, .com and .dll files. When the user uses these files, the virus attached with these files is activated. It infects other files and performs destructive commands and destroys data files.
2. Chernobal virus
The famous chernobal virus deletes all Microsoft office files. It also deletes the partition information from the disk that causes a major loss of data.
3. Logic bomb
Logic bomb is also called time bomb. It differs from other viruses. It is activated al a certain data and time. Michelangelo is an important logic bomb. It destroys data on the hard disk on march 06.
4. Trojan Horse
Trojan horse hides itself as useful program. It contains hidden instructions to erase data or cause other damage. It executes illegal, destructive instructions in the middle of a program such as computer game. FormatC is an example of a Trojan horse.
Redlof is a polymorphic virus. It is written in visual basic script. It relies on the Microsoft activeX component to execute itself. It locates folders.htt and infects that file. Folder.htt is part of Microsoft windows active desktop feature.
Some viruses make unnoticeable changes. They corrupt data being used. Some viruses may make data unusable.
A virus may detect some special information like passwords or sensitive data. It may send the data to some other user on a network. For example a virus amy read the pin code or credit card number and then send it to another user. A virus amy also make some resources unavailable to the users. For example, a virus may start sending data on a network. The network may cecome unavailable for the users.
Category: Computer & IT