Malware

Malware is the collective name for a number of malicious software variants, including
viruses, ransomware and spyware. Shorthand for malicious software, malware typically
consists of code developed by cyberattackers, designed to cause extensive damage to data
and systems or to gain unauthorized access to a network.

“Malware” is short for “malicious software” - computer programs designed to infiltrate and
damage computers without the users consent. “Malware” is the general term covering all
the different types of threats to your computer safety such as viruses, spyware, worms,
Trojans, rootkits and so on.

What does a malware do?

Although malware cannot damage the physical hardware of systems or network equipment
(with one known exception—see the Google Android section below), it can steal, encrypt,
or delete your data, alter or hijack core computer functions, and spy on your computer
activity without your knowledge or permission.

Examples of Malware are as listed below …..

Viruses

A computer virus is a type of malware that propagates by inserting a copy of itself into and
becoming part of another program. It spreads from one computer to another, leaving
infections as it travels. Viruses can range in severity from causing mildly annoying effects to
damaging data or software. Almost all viruses are attached to an executable file, which
means the virus may exist on a system but will not be active or able to spread until a user
runs or opens the malicious host file or program. When the host code is executed, the viral
code is executed as well. Normally, the host program keeps functioning after it is infected by
the virus. However, some viruses overwrite other programs with copies of themselves,
which destroys the host program altogether. Viruses spread when the software or
document they are attached to is transferred from one computer to another using the
network, a disk, file sharing, or infected email attachments.

Worms

Computer worms are similar to viruses in that they replicate functional copies of themselves
and can cause the same type of damage. In contrast to viruses, which require the spreading
of an infected host file, worms are standalone software and do not require a host program
or human help to propagate. To spread, worms either exploit a vulnerability on the target
system or use some kind of social engineering to trick users into executing them. A worm
enters a computer through a vulnerability in the system and takes advantage of file-
transport or information-transport features on the system, allowing it to travel unaided.
More advanced worms leverage encryption, wipers, and ransomware technologies to harm
their targets.
Trojans

A Trojan is another type of malware named after the wooden horse that the Greeks used to
infiltrate Troy. It is a harmful piece of software that looks legitimate. Users are typically
tricked into loading and executing it on their systems. After it is activated, it can achieve any
number of attacks on the host, from irritating the user (popping up windows or changing
desktops) to damaging the host (deleting files, stealing data, or activating and spreading
other malware, such as viruses). Trojans are also known to create backdoors to give
malicious users access to the system. Unlike viruses and worms, Trojans do not reproduce
by infecting other files nor do they self-replicate. Trojans must spread through user
interaction such as opening an email attachment or downloading and running a file from the
Internet.

A Trojan horse or Trojan is a type of malware that is often disguised as legitimate

software. Trojans can be employed by cyber-thieves and hackers trying to gain access to
users' systems. Users are typically tricked by some form of social engineering into loading
and executing Trojans on their systems.

How do Trojans spread?

Unlike viruses and worms, Trojans do not reproduce by infecting other files nor do they self-
replicate. Trojans must spread through user interaction such as opening an email
attachment or downloading and running a file from the Internet

Virus vs Worm
The primary difference between a virus and a worm is that viruses must be triggered by the
activation of their host; whereas worms are stand-alone malicious programs that can self-
replicate and propagate independently as soon as they have breached the system.

What is the difference between virus worm and Trojan horse?

Worms spread from computer to computer, but unlike a virus, it has the capability to travel
without any help from a person. ... A Trojan horse is not a virus. It is a destructive program
that looks as a genuine application. Unlike viruses, Trojan horses do not replicate
themselves but they can be just as destructive.

Ransomware

Ransomware is a type of malicious software that threatens to publish the victim's data or
perpetually block access to it unless a ransom is paid. While some simple ransomware may
lock the system in a way that is not difficult for a knowledgeable person to reverse, more
advanced malware uses a technique called cryptoviral extortion, which encrypts the victim's
files, making them inaccessible, and demands a ransom payment to decrypt them.

Bots

"Bot" is derived from the word "robot" and is an automated process that interacts with
other network services. Bots often automate tasks and provide information or services that
would otherwise be conducted by a human being. A typical use of bots is to gather
information, such as web crawlers, or interact automatically with internet messaging. They
may also be used to interact dynamically with websites.

Distribution Channels for Malware

Advanced malware typically comes via the following distribution channels to a computer or
network:

• Drive-by download—Unintended download of computer software from the Internet

• Unsolicited email —Unwanted attachments or embedded links in electronic mail
• Physical media—Integrated or removable media such as USB drives
• Self-propagation—Ability of malware to move itself from computer to computer or
network to network, thus spreading on its own

Symptoms of a Computer Virus:

There are many warning signs or symptoms which show that a computer is infected with a
virus, some of which are as follows:

o Slow computer performance: The machine may work slowly, e.g., it will take more
time to open or shut down the computer or while opening a file, document,
computer application, etc. The operating system and internet speed may get slow.
o Frequent pop-ups: A virus may cause unusual frequent pop-ups on your window.
o Hard Drive issue: The hard drive may exhibit unusual high activity even when it is
not in use. It may cause unwanted changes to your hard drive and may freeze or
crash this device.
o Frequent crashes: One may experience frequent sudden system crashes while
playing games, watching videos, or doing some other work using the infected
system. A blue screen appears when it crashes.
o Unknown programs: Unwanted programs may open or start automatically when you
start your computer. You can see these programs in your computer's list of active
applications. Sometimes, the window shuts down unexpectedly without any reason.
o Unusual activities: Your machine may perform differently, such as you may not be
able to log into your accounts, to delete the corrupt files, and Blue Screen of Death
(BSOD) may appear frequently, and more. Furthermore, the hardware, software, or
OS may start malfunctioning leading to crashing the system abruptly.
o Impaired security solutions: Sometimes, security measures taken by you, such as
antivirus may not work smoothly due to virus attack on your computer.
o Network issue: Sometimes, you experience high network activity even if you are not
connected to the internet and vice versa.
o Unnecessary advertisement: We often see advertisements while browsing, but if
you see them even when you are not browsing, it may indicate a virus on your
computer.
o Display problems: You may experience different colors in your display if your
computer is affected by a virus.
o Affected Applications: Some viruses are developed to affect specific applications.
Consequently, some applications may not work on your computer if it is infected.
o Blocked by Antivirus Sites: An antivirus site may deny access to a computer that is
infected by a virus.
o Dialog Boxes: Many dialog boxes keep appearing suddenly on your screen.
o Printer Issues: A printer attached to an infected computer may print documents
without getting any command or in an inappropriate manner.
o Changed Homepage: Your home page may get changed without any effort from your
side. For example, you may see a new toolbar on your screen, and you may be
redirected to a different web address instead of the page visited by you initially.