Page 113 - Computer - 7

SOURCES OF MALWARE
Computer viruses usually spread in one of three ways – from removable media, such as CDs, DVDs, and
pen drives, pirated software; downloads from unauthorised websites; and email attachments.

INDICATIONS OF MALWARE INFECTION
Some common warning signals that indicate a computer is infected by malware are:
• The computer becomes slow and programs take a lot of time to load.
• The hard disk does not allow you to save files, even if there is enough
space available.
• The files stored on the computer get deleted on their own.
• The computer stops responding or restarts frequently.
• The hard disk or other disk drives become unaccessible.
• The web browser opens a different page from the one you want to open.
• New files and folders keep appearing on the system, but you do not know where they came from.

TYPES OF MALWARE
Malware has various forms and can infect a computer in different ways. Types
of malware include viruses, worms, trojan horses, rootkits, fileless malware,
ransomware, botnets, adware, spyware, malvertising, phishing, and more.
Let us know more about the various types of malware.

Virus
A Virus is a software that can replicate itself and cause harm to the operating
system, other application software, or data files in a computer. It can spread from
program to program and disk to disk, manipulating and damaging valuable data
without the user’s knowledge.

A virus normally does not act on its own. Once the infected program is executed or the infected file is
accessed, the virus gets activated and infects other programs and files in the computer system. The
effect of a virus can be harmless, such as the display of pop-up messages, or it can be serious, such as
destroying programs and data.

Types of Viruses
Computer viruses are of many types. The way of working and level of harm caused by each type of virus
varies widely. Computer viruses can be classified as:

Boot Sector Virus
A Boot Sector Virus infects boot record program on a hard disk, responsible for loading the operating
system into memory. When a pen drive or DVD infected with a boot
virus is used in the system, the virus installs itself on the hard disk and
replaces the original boot record. When the system is booted with an
infected hard disk, the virus enters the memory and infects all files that
are written to or read from the disk.
Michelangelo, Disk Killer, Brain, and Stoned are examples of boot
sector viruses.

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