Comprehensive Guide to Over 12 Malware Varieties: Definitions & Real-World Instances

Malware is a piece of bad news wrapped up in software. That’s the long and short of it. Malicious software coded with the intent of causing harm to a user, a system, or a network is nothing new, but what’s scary is its continuing evolution into new and invisible forms of threats.

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To combat cyber threats in an enterprise, you need a solid foundation of important topics like what malware is, how it spreads, and all its variants that lurk out there in the wild.

This brief guide covers all the basics you need to know about the malicious program.

Table of Contents

• What is Malware?
  • History of Malware
• Malware Terminologies
  • Ways of Spread
  • Types of Malware Attacks
  • Other Important Terms
• Different Types of Malware
  • 1. Viruses
    * 1a. System or boot infectors
    * 2a. File infectors
    * 3a. Macro viruses
  • 2. Worms
  • 3. Trojan Horses
  • 4. Rootkits
  • 5. Ransomware
  • 6. Keyloggers
  • 7. Grayware
    * 7a. Adware
    * 7b. Spyware

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What is Malware?

Malware definition is simply a malicious code. It is a software that is developed with malicious intent, or whose effect is malicious.

While the effects of such computer viruses often are harmful to users, they are devastating for companies.

The spectrum of malware is wide — and getting wider by the minute.

History of Malware

As you can imagine, the history of malware goes a long way. The term malware may have been introduced by Yisrael Rada in 1990, but these kinds of threats had been in existence decades before, referred to as computer viruses.

Let’s take a look at some common malware.

Malware Terminologies

Here is a quick look at some of the common malware terms and abbreviations that you will see when discussing computer viruses.

Ways of Spread

Drive-by download: The unintended download of computer software from a website via the Internet. User’s get infected by the download that happens without the knowledge, or without the understanding of the consequences.

Homogeneity: A setup where all the systems are running on the same operating system and connected to the same network.

Vulnerability: A security defect in software that can be attacked by malware.

Backdoor**:** An opening or break left in the operating systems, hardware, network or cybersecurity by design.

Types of Malware Attacks

0-Day: A zero-day vulnerability is an undisclosed flaw that hackers can exploit. It’s called 0-day because it is not publicly reported or announced before becoming active.

Exploit: A threat made real via a successful attack on an existing vulnerability.

Privilege escalation: Another type of malware attacks is privilege escalation. A situation where the attacker gets escalated access to the restricted data.

Evasion: Evasion is another type of malware attack. The techniques malware maker design to avoid detection and analysis of their malware by security systems.

Blended threat: A malware package that combines the characteristics of multiple kinds of the malicious program like Trojans, viruses worms, seeking to exploit more than one system vulnerability.

Other Important Terms

Botnet: A number of Internet-connected devices that are running one or more bots. Botnets are used to perform distributed denial of service attacks, send spam, and steal data.

Containment: The process of stopping the spread of malware, and preventing further damage to hosts.

Endpoint: A security approach to the protection of computer networks that are remotely bridged to client devices.

Payload: The part of the malware program that actually does the damage.

Privilege: In computing, privilege means access to modify a system.

Signature: Signs that are specific to either a certain type of behavior or a specific item of malware.

Threat: In computing security, a computer or network is deemed under threat when it harbors persistent software vulnerabilities, thereby increasing the possibility or certainty of a malicious attack

Track: Evidence of an intrusion into a system or a network.

Zombie: The operating systems connected to the Internet that has been compromised by a hacker, computer virus. It can be used to perform malicious tasks.

Different Types of Malware

Running into the word that starts with mal is a literal sign that something is bad. In general, most experts view the term malware as a contraction of two words — malicious software.

So much so that viruses are now just the tip of the iceberg.

Recent study data say that the majority of the malicious programs out there in the wild today are Trojans and computer worms, with viruses having declined in numbers. A 2011 study had Trojan horses amount to 69.99% of all malware tracked, while viruses only made up 16.82%. This is a number that has clearly gone up.

A more recent study in 2017 found that malware aimed at mobile devices like smartphones and tablets is increasing at an alarming rate, and even coming pre-installed on devices .

But what are the various types of malware, and how exactly are they classified?

Let’s see how attackers install and deploy these malware types.

Antivirus vs Anti-Malware

1. Viruses

The primary characteristic that a piece of software must possess to qualify as a virus is an urge to reproduce that is programmed into it. This mechanism means that this type of malware will distribute copies of itself, using any means to spread.

They hide within computer files, and the computer must run that file (execute that code, in other words) for a virus to do its dirty functions.

How Antivirus Works?

1a. System or boot infectors

A virus can infect a system as a resident virus by installing itself as part of the operating system.

2a. File infectors

Many viruses sneak up into ordinary executable files like .EXE and .COM in order to up their chances of being run by a user. Programs including batch files and script files like .BAT, .JS. .VB, and .SCR extension is susceptible.

3a. Macro viruses

These kinds of viruses are the ones that run inside specific application files that allow macro programs in order to extend the capabilities of a given software.

Some infamous examples of viruses over the years are the Concept virus, the Chernobyl virus (also known as CIH), the Anna Kournikova virus, Brain and RavMonE.exe.

2. Worms

The second of the two kinds of infectious malware. A worm is a standalone software that replicates without targeting and infecting specific files that are already present on a computer. They usually target the operating system files and work until the drive they are in becomes empty.

Basically, whereas viruses add themselves inside existing files, worms carry themselves in their own containers.

Computer worms usually show up via email and instant messages. They use a computer network to spread.

Difference between Virus and Worm

Examples include Melissa, Morris, Mydoom, Sasser, Blaster, and Mylife.

3. Trojan Horses

A Trojan is a malicious program that misrepresents itself to appear as a legitimate program. The term is derived from the Ancient Greek story of the wooden horse that was used to invade the city of Troy by stealth — these are just as deadly on computers.

Trojan horse payload is usually a backdoor that allows attackers to gain access to the infected computer. Trojans also give cybercriminals access to the personal information of a user like IP addresses, passwords and banking details.

Trojan horse is now considered to be the most dangerous of all malicious program, particularly the ones that are designed to gain access and steal sensitive information from the victim’s computer.

5 Best Trojan Removal Tools

Example – Notable examples also include Trojan developed by government agencies like the FBI, NSA, and GCHQ. Names like Magic Lantern, FinFisher, WARRIOR PRIDE, Netbus, Beast, Blackhole exploit kit, Gh0st RAT, Tiny Banker Trojan, Clickbot.A, Zeus, and Android Trojan Shedun.

4. Rootkits

A rootkit is a collection of software specifically designed to permit malicious program that gathers sensitive information, into your system.

These software work like a back door for different types of malware to enter and gain access, and are now being used extensively by hackers to infect systems.

The root access in other words.

Detecting and removing a rootkit is difficult — more so in cases where the rootkit resides inside the kernel of an operating system. Reinstalling the operating systems is often the only solution to protect your PC.

Example – The first malicious rootkit to gain notoriety on Windows was NTRootkit in 1999, but the most popular is the Sony BMG copy protection rootkit scandal .

5. Ransomware

The most devastating type of malicious programs, by some counts. Definitely one of the most advanced and constantly on the rise these days. Ransomware blocks access to the data of a victim, threatening to either publish it or delete it until a ransom is paid. Worse yet, there is no guarantee that paying a ransom will return access to the data, or prevent it from deletion. Usually, ransomware uses phishing to spread.

This manner of digital extortion has been in play since the late 80s, it returned to prominence in late 2013 with the advent of digital currency that is used to collect the ransom money.

6. Keyloggers

Software that records all the data that is typed using a keyboard. Keyloggers usually are not capable of recording information that is entered using virtual keyboards and other input devices, but physical keyboards are at risk with this type of malware.

Keyloggers store the gathered data and send it to the attacker, who can then extract sensitive data like username and passwords as well as credit card details.

7. Grayware

Grayware is a recently coined term that came into use around 2004. It is used to describe unwanted applications and files that though are not classified as a malicious program, can worsen the performance of computers and lead to security risks.

Grayware alludes to both adware and spyware. Almost all commercially available security software can detect these potentially unwanted programs .

7a. Adware

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Although ad-supported software is now much more common types and known as adware in some circles, the word has been linked to malicious program for quite some time. While adware can refer to any program that is supported by advertising, malicious adware usually shows advertisements in the form of popups and windows.

It is perhaps the most lucrative and least harmful malware, designed with the specific purpose of displaying advertisements on your computer .

How to Remove Adware from Google Chrome

7b. Spyware

Spyware , as the name gives away, is software that constantly spies on you. Its main purpose is to keep track of your Internet activity in order to send adware. Spyware is also used to gather sensitive information about an organization without their knowledge, and send that data to another entity, without consent of the victim.

What can Hackers do with Malware?

Hackers can gain full access to your computer using the malicious program. They can steal your sensitive files like images and personal videos. They can deploy keyloggers that could steal your confidential information like bank login details and credit card information. Or simply hackers could use your PC to deploy an attack.

What is the Most Dangerous Malware?

All malicious program is created to harm the users. While some of them are just to annoy users and track their activity, others could cause significant damage. Some of the most dangerous malware are Ransomware, Rootkits, and Trojan horse.

Is a Virus a Type of Malware?

Yes, malware is a malicious program. Every software that is created with malicious intent is malware. Viruses are designed to delete and corrupt the user’s data. Thus they are malicious.

How is Malware Spread?

The malicious program uses various means to spread. Some of the major methods are drive-by download, homogeneity, vulnerability, and backdoor.

20 thoughts on “List of Types of Malware”

1. 
   Ion Ciuca

September 3, 2017 at 5:13 am
thank you for mentioning all kind of bad software!
Congratulations!
Reply

• 
  Earl Randhawa

August 22, 2018 at 12:22 pm
I got what you mean , thanks for putting up.
Reply
2.
Leo C.T.

October 15, 2017 at 9:32 pm
Informative and helpful overview.
Thank you for sharing!
Reply
3.
Sandeep
October 24, 2017 at 1:41 am
Hi,
very useful updated information about different types of this infection…!!
Reply
4.
Nubian
December 20, 2017 at 1:00 am
Thank you for the information. This was very helpful!
Reply
5.
Mahesh
May 26, 2018 at 6:18 pm
That is very useful and pointed information about emerging computer malwares
Reply

• 
  mahesh420
  March 19, 2019 at 12:26 am
  That is very useful and pointed information about emerging computer malwares
  Reply

6. 
   Last Marara
   November 1, 2018 at 7:37 pm
   Very helpful, Thank you
   Reply
7. 
   bob
   April 9, 2019 at 7:42 am
   epic
   Reply
8. 
   yurt blitherwart

April 24, 2019 at 9:15 pm
thank you kanye, very cool!
Reply
9.
Vivek Kumar Singh

May 11, 2019 at 10:56 pm
very helpful.
Reply
10.
onganyo1

June 24, 2019 at 8:47 pm
Thanks for the overview
Reply
11.
Sechaba Edgar Nthako
October 3, 2019 at 12:17 pm
I didn’t know the cause of my keyboard logged keys. I am thankful now I know it’s a malicious program
Reply
12.
Sam

April 14, 2020 at 8:41 pm
This was very informative. Thank you for sharing!
Reply
13.
Jan

May 13, 2020 at 3:08 am
When I open Task Manager how do I know by looking at the names of all the processes performing which ones are PUPs or other malware and which ones are legitimate programs?
Reply

• 
  GameResetYT

March 22, 2021 at 5:57 pm
What is a PUP tho? Sounds like a puppy! I like puppies!
Reply
14.
Kristel

August 24, 2020 at 10:26 pm
Hello Shawn! I’m very glad to read this very informative article as it explains everything properly especially on the type of malware. Didn’t know that keyloggers can be a malware.
Reply
15.
GameResetYT

March 22, 2021 at 5:56 pm
Thank you! Im doing a malware types project for my school and this helped a lot. Also, i wanted to mention, you could also mention “scareware” which attempts to scare the users, usually with disturbing photos, gore, etc. Some examples are NoEscape.exe, MrsMajor, 000.exe… There are hundreds!
Reply
16.
Eden Okata
May 1, 2021 at 2:14 pm
I have a project to do and it’s given me a tip. Thanks!!
Reply
17.
miriam
September 17, 2021 at 7:08 pm
so good explanations…wow
Reply

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