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• They can reduce or block the memory of the computer or hard disk.
• They can prevent you from restarting your computer or cause it to restart repeatedly.
• They send e-mails from your account without your knowledge.
i + TYPES OF COMPUTER VIRUS
There are various types of computer viruses that infect the computer in different ways. The most
commonly known categories of computer viruses are:
• Program File Virus • Boot Sector Virus • Macro Virus • E-mail Virus
Let us learn about these in detail.
Program File Virus
A program file infecting virus is a type of malware that targets the executable files such as .exe or
.com files of a program with the intention of causing permanent damage or making the program
useless. This type of virus typically inserts its code into the existing code of a program file, ensuring
that it is activated whenever the infected program is executed. Once active, the virus can spread
to other files, corrupt data, or disrupt system operations. A program file infecting virus is also
known as a ‘File Injector’. Sunday and Cascade are the common examples of program viruses.
Boot Sector Virus
Booting is the process of loading operating system in the primary memory from the boot sector. The
boot sector is a critical section of a storage device that contains the code necessary to start the boot
process.
A boot sector virus is a type of malware that infects the boot sector or the Master Boot Record
(MBR) of a storage device. The MBR is the first sector of a hard drive that contains information
about how to load the operating system into memory.
A boot sector virus can replace or alter the MBR or boot sector code, preventing the operating
system from loading correctly and causing errors during the boot process. Examples of boot
sector viruses include Michelangelo, Polyboot.B, Stones, and AntiEXE.
Macro Virus
A macro virus is a type of computer virus that is primarily designed to infect a specific type of
document, such as Word or Excel files. When a user opens an infected document, the macro virus
activates and can execute malicious actions, often including the infection of other documents.
Sometimes, a macro virus sends itself as an e-mail attachment to the people in the user's address
book. Melissa and Bablas are the most commonly known macro viruses.
E-mail Virus
An e-mail virus is a type of computer virus that is transmitted from one computer to another
through e-mail messages. It often arrives as an infected attachment or, in some cases, through
malicious links within the email body. It gets active in the memory when a user opens an infected
e-mail or attachment. Email viruses can cause significant harm, such as deleting files, corrupting
data, or crashing systems.
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