Common Malware Types and How They Infect a User's Computer

Common Malware Types Definition:

Any program intended to damage, interfere with, or grant illegal access to a computer system or network is known as malware, short for malicious software.

Malware can appear in a variety of forms, from the some the most complex to the simplest malware types:

This is a list of some of the most common malware types that are prevalent in todays digital world.

Viruses

A harmful piece of software (malware) with the ability to proliferate and infect computers is called a computer virus. To deceive people into running it, it is frequently cloaked as a trustworthy application or file. A computer virus can interrupt system operations, damage or change files and data, propagate to other computers, and other negative effects after it has entered a system.

What a Computer Virus Does to a Computer:

Computer viruses are created to carry out a variety of evil deeds, and they can have a variety of different impacts. When a computer is infected, a computer virus can do the following typical tasks:

Replication: The primary characteristic of a computer virus is its ability to self-replicate. It can make copies of itself and spread to other files, programs, or even other computers, increasing its presence.
Data Corruption or Deletion: Many viruses are programmed to corrupt or delete files, which can lead to the loss of valuable data. They may also damage the file system, making it difficult to recover the affected files.
System Performance Issues: Viruses can consume system resources, causing a computer to slow down or become unresponsive. This can result in reduced performance and productivity.
Unauthorized Access: Some viruses are designed to provide unauthorized access to a computer, allowing hackers to control the infected system remotely. This can lead to data theft, privacy breaches, and further system compromise.
Spreading to Other Computers: Viruses often seek to infect other computers on the same network or through shared files, email attachments, or removable media (like USB drives). This can lead to a widespread outbreak.
Displaying Unauthorized Messages: Certain viruses may display annoying or malicious messages on the infected computer, disrupt normal operations, or even demand a ransom (as in ransomware).
Modifying or Disabling Security Software: Some viruses can alter or disable antivirus and security software, making it harder to detect and remove them.
Network Traffic Manipulation: Certain viruses can manipulate network traffic, redirecting users to malicious websites or intercepting sensitive information.
Botnet Participation: Some viruses turn infected computers into “bots” that can be remotely controlled by cybercriminals. These botnets are often used for various cybercrimes, including distributed denial-of-service (DDoS) attacks.
Data Theft: Viruses can be designed to steal sensitive information, such as login credentials, personal data, or financial information, which can then be used for identity theft or fraud.

How Computer Viruses Infect Other Computers:

Email attachments: Email attachments are one of the most popular ways that viruses propagate. An unknowing victim will frequently receive an infected file as an attachment from hackers. The virus will run and infect the machine when the victim opens the attachment.
Downloading infected software: On occasion, hackers will spread malicious malware online. The virus will run and infect users’ computers when they download and install the program.
Infected websites: Viruses can be spread by hackers onto trustworthy websites. Users may get the virus and have their computers infected when they visit the compromised website.
Removable media: Additionally, viruses can propagate via detachable storage devices like CDs and USB drives. The virus could run and infect the computer if an infected device is linked to it.
Exploiting vulnerabilities: In order to infect computers, hackers might also take advantage of weaknesses in software or operating systems. They could deceive people into downloading and running the virus by using social engineering or phishing scams, among other methods.

Examples of Most Recent Viruses:

Ryuk: Ryuk is a kind of ransomware that first appeared in 2018 and is still present today. The decryption key is demanded in exchange for considerable quantities of money from its target corporate enterprises.
Trickbot: Trickbot is an active banking Trojan that dates back to 2016. Over time, it has changed and added additional capabilities, such the capacity to steal login credentials and propagate to other machines on a network..
Emotet: Emotet was originally identified as a malware botnet in 2014. It is typically used to distribute other software, including banking Trojans and ransomware.
SolarWinds: The SolarWinds hack was an assault on the supply chain that was found in December 2020. It entailed injecting malware into software updates for the SolarWinds Orion platform, which is utilized by several significant corporations and government institutions.
Hafnium: Hafnium is a state-sponsored hacker gang that launched many assaults against Microsoft Exchange Server in the beginning of 2021. The attacks were believed to have compromised tens of thousands of firms throughout the globe.

Worms

While both worms and viruses have the ability to replicate themselves, viruses do so by using other programs or data.

Worms, on the other hand, may independently propagate across systems and networks. Once a computer has been infected by a worm, it may offer hackers access to the system through a “backdoor” and steal private information.

How Computer Worms Infect Other Computers:

Exploiting software vulnerabilities: Operating system flaws and other software weaknesses can be used by worms to enter a computer. Once a computer has been infected, the worm can search the network for more susceptible machines to attack.
Sending themselves through email: By distributing copies of themselves to the contacts in an infected computer’s address book, worms can also propagate over email. The worm can infect the recipient’s machine when they open the email and open the attachment.
Using instant messaging and social media: Worms may also propagate via social media and instant messaging by distributing links to infected files or websites. The worm can download and run on the user’s machine after they click the link.
Exploiting removable media: Some worms can also propagate via portable storage devices like CDs or USB drives. The worm may run and infect a computer when an infected device is linked to it.
Using network shares: Shared network folders can potentially be used by worms to infect other machines. The worm can look for shared files on the network when one computer is infected, then utilize those folders to propagate to additional infected machines.

Examples of Computer Worms:

Morris Worm: The Morris Worm is among the most well-known computer worms ever. Robert Morris, a PhD student, developed it in 1988, and it quickly swept throughout the internet, seriously harming computer systems. The worm replicated itself, clogged networks, and crashed computers by taking advantage of flaws in Unix systems.
Conficker: Conficker is a worm that initially surfaced in 2008 and spread over millions of systems. It propagated by taking advantage of a flaw in Microsoft Windows, downloading more software onto affected computers to give hackers control over them.
Stuxnet: Stuxnet is a worm that was found in 2010 and is thought to have been created by the US and Israel to attack Iran’s nuclear program. The worm attacked industrial control systems and physically harmed uranium enrichment centrifuges.

How the U.S. Hacked Iran’s Nuclear Facility

Trojans

Trojans are forms of malware that pretend to be a trustworthy application or file.

The Trojan can perform a number of malicious activities after it has been downloaded and installed, such as steal data or grant remote access to the machine.

The most common ways that trojans are propagated are through phishing emails and misleading software downloads.

How Computer Trojans Infect Other Computers:

Bundled with other software:Online malware transmissions involving trusted software programs are also possible. When people download and install a program, the Trojan will also be installed on their computers along with the software.
Email attachments: Like other types of malware, trojans may spread through email attachments. When the user opens the attachment, the Trojan will launch and infect the computer.
Social engineering attacks: Trojans can also spread through social engineering attacks, in which the attacker manipulates the target into installing the Trojan. As an example, an attacker may send the victim an email that seems to be from a reliable organization urging them to apply a software update. The Trojan will be placed on the user’s PC when they apply the update.
Drive-by downloads: Another way to propagate Trojans is by drive-by downloads, which take place when a user visits a website that is infected and the Trojan is downloaded and installed without their knowledge.
Software vulnerabilities:Trojans may also infect computers through software weaknesses. For instance, a Trojan may download and set up shop on a user’s machine by exploiting a web browser bug.

What is a Trojan Horse and How Does It Work?

Examples of Computer Trojans:

Zeus: Zeus, also known as Zbot, is a Trojan that first appeared in 2007. It is primarily used for stealing banking credentials and has been responsible for the theft of millions of dollars from individuals and organizations worldwide.

What is Zeus or ZBot Trojan?

SpyEye: SpyEye is another banking Trojan that emerged around the same time as Zeus.It was created by a separate gang of hackers but shares many of Zeus’ features.
Back Orifice: Back Orifice is a Trojan The Cult of the Dead Cow, a gang of hackers, initially published the Trojan called Orifice in 1998. A computer may be accessed remotely, providing hackers access to the network.
BlackEnergy: BlackEnergy is a Trojan that was first discovered in 2007. It has been used in a variety of attacks, including the 2015 Ukraine power grid cyberattack. The Trojan is capable of disabling security software and giving hackers control over infected systems

Ransomware

a form of malware that encrypts a user’s data and requests money in exchange for the key to unlock them.

There are several ways that a computer might get infected with ransomware, including email attachments, fake software updates, and malicious websites.

Ransomware Explained?

How Ransomware Infect Other Computers:

Email phishing: Email phishing assaults, in which the attacker sends a legitimate-looking email with a malicious attachment or a link to a malicious website, can spread ransomware. The ransomware is downloaded and run on the victim’s computer when they open the attachment or click the link.
Drive-by downloads: Drive-by downloads, in which the victim inadvertently accesses a website that is infected and downloads and runs the ransomware on their computer, are another way that ransomware may propagate.
Exploiting vulnerabilities: In order to infect computers, ransomware can also take use of weaknesses in software or operating systems. Users may be tricked into downloading and running ransomware by attackers using strategies like phishing or social engineering.
Infected software: Additionally, corrupted software can spread ransomware. On the internet, hackers may disseminate tainted software, and when consumers download and install it, the ransomware is launched on their machine.
Remote desktop protocol (RDP) attacks: virus may also spread using RDP attacks, in which the attacker connects to the victim’s computer remotely to get access and install the virus.

Some Examples of Ransomware:

WannaCry: In 2017, this ransomware outbreak hit more than 200,000 systems across 150 different countries. It exploited a vulnerability in Microsoft Windows and demanded payment in Bitcoin to unlock the victim’s files.
Petya/NotPetya: This ransomware attack in 2017 affected several major companies worldwide. It spread through a software update and encrypted the victim’s files, demanding a Bitcoin payment for decryption.
Locky: This ransomware was first discovered in 2016 and spread through email phishing campaigns. It encrypted the victim’s files and demanded payment in Bitcoin to unlock them.
Ryuk: is Ransomware often distributed through malicious spam emails and has been responsible for several high-profile attacks against government organizations, healthcare providers, and financial institutions.
Maze: This ransomware attack was first discovered in 2019 and was known for stealing the victim’s data before encrypting it. Once they had the decryption key, the attackers would demand money and threaten to reveal the data they had stolen if the ransom was not paid.

Spyware

Spyware is a covert class of malicious software that was created with the sinister intent of secretly tracking and gathering sensitive user data.

This data can include a variety of private and sensitive details, including login information, credit card information, and even browsing patterns.

This intrusive malware functions covertly, frequently eluding the user’s knowledge and, in certain situations, even prevailing antivirus defenses.

Spyware may enter a computer using a variety of ingenious entry points. Here are some further details on how spyware infestations work and their effects:

Ways Spyware can Infect your Computer:

Software Downloads: Spyware can be downloaded together with seemingly innocent programs and is frequently packed with beneficial programs or utilities. Spyware might be unintentionally installed alongside software that users meant to use, acting as a sneaky partner.
Social Engineering Techniques: Social engineering techniques are used by cybercriminals to persuade consumers into downloading malware without their knowledge. These strategies may include false system alarms, fraudulent pop-up adverts, or alluring offers that induce users to click on harmful URLs or download harmful files.
Email Attachments: Email attachments are another popular method for distributing malware. Cybercriminals send emails with seemingly innocent attachments that are compromised. When the attachment is opened, malware might enter the user’s computer and start secretly watching them.
Drive-By Downloads: Drive-by downloads, when malicious malware is run when a user visits a hacked website, are another way that spyware may infect a computer. This technique delivers and installs malware without the user’s knowledge by taking advantage of flaws in web browsers or plugins.
File Sharing: Peer-to-peer (P2P) file-sharing networks can be used to spread certain malware. Users run the danger of unintentionally installing malware along with the desired material while downloading files from these networks.

Effects of Spyware on your Computer:

Infections with spyware have serious, diverse effects. In addition to jeopardizing private information, spyware may dramatically reduce computer speed, impede internet access, and interfere with standard system operations.

It may also result in financial losses, privacy violations, and identity theft.

Users are advised to maintain strong cybersecurity practices, such as routinely updating their operating systems and software, using reliable antivirus and anti-spyware tools, exercising caution when downloading software or clicking on links, and carefully examining email attachments for legitimacy, in order to protect themselves against spyware.

In order to mitigate this widespread threat in the digital era, user education and knowledge about the risks of spyware and its numerous penetration tactics are essential.

Examples of Spyware:

FinFisher: Governments deploy this malware to keep an eye on their populations’ internet activity. It has the ability to intercept emails, record keystrokes, and take screenshots.
AdLoad: This spyware is used by advertisers to track users’ online behavior and display targeted ads. It can also install other malware on the victim’s computer.
Netbus: This spyware is a remote access tool that allows an attacker to control a victim’s computer. It can be used to monitor the victim’s activities, steal sensitive information, or install other malware.
FlexiSPY: This spyware is marketed as a parental control app, but it can also be used for spying on employees or partners. It can record phone calls, track location, and capture text messages.
Regin: This spyware is a sophisticated tool used by nation-state actors to conduct espionage. It can steal passwords, capture screenshots, and monitor network traffic.

Adware

What is Adware from a Computer Security Standpoint?

Adware, short for “advertising-supported software,” is a type of potentially unwanted program (PUP) that displays advertisements to computer users. While not as malicious as malware or viruses, adware can be disruptive and compromise a user’s online privacy. Here’s a closer look at adware from a computer security standpoint:

1. How Adware Infects a Computer:

Bundled Software: Adware often comes bundled with legitimate software or free applications, which is why it’s essential to be cautious during software installations.
Drive-by Downloads: In some cases, adware can be silently installed on a user’s computer when they visit a compromised or malicious website without their consent.
Malicious Links or Email Attachments: Clicking on malicious links or downloading email attachments from unknown sources can also lead to adware infections.

2. Effects of Adware on a Computer System:

Advertisement Display: The primary purpose of adware is to display advertisements. These can be in the form of pop-ups, banners, or auto-playing videos, often disrupting the user’s online experience.
Browser Modifications: Adware may alter browser settings, such as the homepage, search engine, or install browser extensions without user consent.
Tracking and Privacy Issues: Many adware programs track user behavior, collecting data on browsing habits, which can lead to privacy concerns.
System Slowdown: Adware can consume system resources, leading to slower computer performance.
Security Risks: Some adware may also open vulnerabilities in the system, potentially making it easier for more malicious software to infect the computer.

3. Examples of Well-Known Adware Programs:

Conduit: Conduit is notorious for changing browser settings and redirecting users to Conduit’s search engine. It is often bundled with free software.
Superfish: Superfish came pre-installed on some Lenovo laptops and injected third-party ads into web pages, creating security vulnerabilities.
Genieo: Genieo is known for tracking user behavior and modifying browser settings. It can be bundled with free software downloads.
AdChoices: While AdChoices is a legitimate advertising program, it can be considered adware if it displays excessive, intrusive ads.
Vonteera: This adware infects computers through software bundling and displays various types of ads, including pop-ups.

It’s essential for users to protect their computers by being cautious during software installations, avoiding downloading from suspicious websites, regularly updating their security software, and using browser extensions or ad blockers to help mitigate the impact of adware. Removing adware from an infected computer often requires the use of reputable anti-malware or antivirus software.

Rootkits

Rootkits are a type of malware that are designed to hide their presence on a user’s computer. Once a rootkit has infected a computer, it can allow cybercriminals to remotely control the system and steal data.

Ways that Rootkits can Infect a Users Computer:

Exploiting vulnerabilities in software: Rootkits can exploit vulnerabilities in software such as web browsers, plugins, and operating systems to gain access to a computer.
Social engineering: Attackers may use social engineering techniques such as phishing emails or social media messages to trick users into clicking on a link or downloading an attachment that contains the rootkit.
Drive-by downloads: Drive-by downloads occur when a user visits a website that has been compromised, and the website automatically downloads and installs the rootkit without the user’s knowledge or consent.
Bundled with legitimate software: Rootkits can be bundled with legitimate software and installed along with it. This can occur when a user downloads software from an untrusted source or fails to read the installation prompts carefully.

Fileless Malware

Fileless malware is a type of malware that does not rely on files to infect a computer. Instead, it resides in the computer’s RAM or other system components, making it difficult to detect and remove.

Ways that Faceless Malware infect a Users Computer:

Fileless malware can infect a computer in several ways, including:

Exploiting vulnerabilities in software: Fileless malware can exploit vulnerabilities in software such as web browsers, plugins, and operating systems to gain access to a computer’s memory.
Social engineering: Attackers may use social engineering techniques such as phishing emails or social media messages to trick users into clicking on a link or downloading an attachment that contains the malware.
Malvertising: Malicious advertisements (malvertising) can be used to deliver fileless malware. These ads can be displayed on legitimate websites, and when a user clicks on them, they may be redirected to a site that contains the malware.
Watering hole attacks: In a watering hole attack, attackers compromise a website that is frequently visited by a specific group of users. When users visit the site, they may unknowingly download the fileless malware.

Cryptojacking Malware

Type of malware that uses a user’s computer to mine cryptocurrency without their knowledge or consent.

Cryptojacking malware can slow down a computer and cause it to overheat, leading to hardware damage.

Ways that Cryptojacking Malware can Infect a Computer:

Drive-by downloads: Cryptojacking malware can be installed on a user’s computer when they visit a website that has been compromised. The website may automatically download and install the malware without the user’s knowledge or consent.
Phishing emails: Attackers may use phishing emails to trick users into downloading and installing the cryptojacking malware. The email may contain a link or attachment that, when clicked or downloaded, installs the malware on the user’s computer.
Malicious ads: Malicious ads (malvertising) can be used to deliver cryptojacking malware. These ads can be displayed on legitimate websites, and when a user clicks on them, they may be redirected to a site that contains the malware.
Software vulnerabilities: Cryptojacking malware can exploit vulnerabilities in software such as web browsers, plugins, and operating systems to gain access to a user’s computer.

Banking Malware

Malware that are designed to steal sensitive information, such as login credentials or banking information, from a user’s computer.

Banking malware is often spread through phishing emails or fake software updates.

Bots

Malware that are designed to perform automated tasks on a user’s computer, such as sending spam emails or launching DDoS attacks.

Ways that Computers can become infected by Bots:

Malicious software downloads: Bots can be installed on a user’s computer when they download and install malicious software, often disguised as legitimate software or files.
Malicious email attachments: Bots can be spread through email attachments that appear to be legitimate, such as Microsoft Office documents or PDF files. Once the attachment is opened, the bot can be installed on the user’s computer.
Drive-by downloads: Bots can be installed on a user’s computer when they visit a website that has been compromised. The website may automatically download and install the bot without the user’s knowledge or consent.
Social engineering: Attackers may use social engineering techniques such as phishing emails or social media messages to trick users into clicking on a link or downloading an attachment that contains the bot.

Backdoors

A malware backdoor is a type of malware that creates a hidden access point in a victim’s computer that can be used by attackers to gain remote access to the computer without the user’s knowledge or consent.

Ways that Backdoors infect a Users Computer:

Phishing emails: Attackers may use phishing emails to trick users into downloading and installing the malware backdoor. The email may contain a link or attachment that, when clicked or downloaded, installs the malware on the user’s computer.
Software vulnerabilities: Malware backdoors can exploit vulnerabilities in software such as web browsers, plugins, and operating systems to gain access to a user’s computer. Once the malware backdoor gains access, it can be used to install additional malware or to create a remote access point.
Malicious downloads: Malware backdoors can be installed on a user’s computer when they download and install malicious software, often disguised as legitimate software or files.
Drive-by downloads: Malware backdoors can be installed on a user’s computer when they visit a website that has been compromised. The website may automatically download and install the malware backdoor without the user’s knowledge or consent.

Keyloggers

Keyloggers are malware that are designed to record a user’s keystrokes.

This allows cybercriminals to capture sensitive information, such as passwords or credit card numbers.

How do Keyloggers infect a users Computer:

Phishing emails: Attackers may use phishing emails to trick users into downloading and installing the keylogger. The email may contain a link or attachment that, when clicked or downloaded, installs the keylogger on the user’s computer.
Software vulnerabilities: Keyloggers can exploit vulnerabilities in software such as web browsers, plugins, and operating systems to gain access to a user’s computer. Once the keylogger gains access, it can be used to record every keystroke made on the computer.
Malicious downloads: Keyloggers can be installed on a user’s computer when they download and install malicious software, often disguised as legitimate software or files.
Drive-by downloads: Keyloggers can be installed on a user’s computer when they visit a website that has been compromised. The website may automatically download and install the keylogger without the user’s knowledge or consent.

Ad Fraud Malware

Ad fraud malware is a type of malware that generates fake clicks on online ads. This can lead to advertisers paying for clicks that are not genuine, resulting in financial losses.

Examples of Ad Fraud Malwares:

Kovter: Kovter is a Trojan malware that hijacks users’ web browsers and generates fraudulent ad clicks in the background. It is particularly effective at avoiding detection by security software.
Methbot: Methbot is a sophisticated ad fraud scheme that uses a network of infected computers to generate fake video ad impressions. It is estimated to have cost the advertising industry millions of dollars in lost revenue.
Chameleon: Chameleon is a botnet that infects computers and mobile devices to generate fake ad clicks and traffic. It can be difficult to detect because it uses a range of techniques to avoid detection by security software.
Redirect: Redirect is a type of ad fraud malware that hijacks users’ web browsers and redirects them to fake websites, generating fraudulent ad clicks in the process.
Zeus: Zeus is a Trojan malware that is primarily known for stealing financial information, but it can also be used for ad fraud. It can hijack users’ web browsers and generate fraudulent ad clicks, as well as carry out other malicious activities.

Macro Viruses

These are malware that infect software macros, which are small programs that automate tasks within larger software programs.

Macro viruses can spread through email attachments or malicious websites.

Examples of Macro Viruses:

Melissa: This macro virus was one of the first major macro viruses and caused widespread damage in 1999. It infected Microsoft Word documents and sent copies of itself to the first 50 people in a user’s Microsoft Outlook address book.
Concept: The Concept virus was first detected in 1995 and infected Microsoft Word documents. It was notable for its ability to spread quickly and for its message that appeared when infected documents were opened: “That’s enough to prove my point.”
Bablas: This macro virus appeared in 2000 and infected Microsoft Excel files. It was particularly dangerous because it could delete files and format hard drives.
W97M.Marker: This macro virus appeared in 1999 and infected Microsoft Word documents. It was notable for its ability to infect multiple platforms, including Windows, Macintosh, and Unix.
X97M.Thus: This macro virus appeared in 1999 and infected Microsoft Excel files. It was particularly sneaky because it didn’t immediately show any signs of infection, making it difficult to detect.

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The Evolution of Malware

In recent years, cybercriminals have become increasingly sophisticated in their use of malware. They use a variety of techniques to infect systems, such as:

Social engineering
Exploiting software vulnerabilities
Drive-by downloads
And more

The Importance of Awareness

It’s now more important than ever for computer users to be aware of the various types of malware and the methods they use to infect systems. This article will provide an overview of:

The most common types of malware
The most common methods of infection
Steps users can take to protect themselves from malware and minimize the risk of infection

Whether you’re a casual computer user or a business owner with sensitive data to protect, this information is essential for keeping your computer and your data safe. By understanding the different types of malware and how they work, you’ll be better equipped to avoid falling victim to cyberattacks and other malicious activities.

Common Malware Types and How They Infect a User’s Computer