51 Types of Malware: Detailed Explanation of Every Threat

Introduction

Malware, short for “malicious software,” refers to any software intentionally designed to cause harm, steal data, disrupt systems, or exploit vulnerabilities in devices and networks. The variety of malware threats has grown significantly, ranging from simple viruses to complex, self-replicating worms and ransomware attacks. Understanding the many types of malware is key to protecting your devices, systems, and sensitive information. In this extensive guide, we will cover over 40 types of malware, detailing how they operate, real-world examples, and protective measures you can take to avoid falling victim to these attacks.

Want to learn about What is a malware? Click here to read: Malware 101: Understanding What It Is, Types, and How to Protect Your System

1. Virus

A virus is one of the most commonly recognized forms of malware. It attaches itself to legitimate files or programs, and once executed, it spreads to other files and systems.

How it Works: Viruses rely on human interaction to spread. They attach themselves to executable files, documents, or software programs. Once the infected file is executed, the virus spreads to other files or systems connected to the same network.
Example: The ILOVEYOU virus, which spread rapidly in 2000 via email attachments, caused over $10 billion in damage worldwide by overwriting files and infecting millions of computers.
Protection: Keeping antivirus software updated, using firewalls, and not opening suspicious email attachments are the best ways to protect against viruses.

2. Worm

Unlike viruses, worms do not need a host file to replicate. They are self-replicating and can spread across networks without user intervention.

How it Works: Worms exploit vulnerabilities in software or systems to propagate through networks, often overwhelming servers or data systems by flooding them with traffic, leading to a crash.
Example: The WannaCry worm, which spread in 2017 by exploiting a vulnerability in Windows systems, encrypted files and demanded ransom from victims while affecting over 230,000 computers across 150 countries.
Protection: Regularly updating operating systems and software can prevent worms from exploiting known vulnerabilities.

3. Trojan Horse (Trojan)

A Trojan disguises itself as a legitimate application or file to trick the user into installing it. Once inside, it opens the door for other malicious actions.

How it Works: Trojans typically appear as innocent programs or files, such as software, games, or updates. Once executed, they often allow cybercriminals to remotely control the infected device, steal data, or install additional malware.
Example: The Emotet Trojan initially started as a banking Trojan but evolved into a powerful malware distribution tool used in targeted attacks across multiple sectors.
Protection: Avoid downloading software from untrusted sources and always verify the legitimacy of software through reviews and verified providers.

4. Ransomware

Ransomware is one of the most dangerous forms of malware today. It encrypts the victim’s data and demands payment in exchange for the decryption key.

How it Works: After infecting a system, ransomware locks files or entire systems, rendering them inaccessible to the user. Attackers demand a ransom, typically in cryptocurrency, to provide the decryption key.
Example: NotPetya (2017) was initially thought to be ransomware but was later identified as a wiper malware used to disrupt operations in the Ukraine, causing widespread damage to companies.
Protection: Regularly back up your files, use strong antivirus protection, and avoid clicking on suspicious links or email attachments.

5. Spyware

Spyware is malware designed to secretly monitor and collect information from users without their knowledge.

How it Works: Spyware runs silently in the background, tracking user activities like browsing habits, login credentials, and financial transactions. The stolen information is then sent back to the attacker.
Example:
, a well-known spyware, hijacked browsers, redirected users to unwanted websites, and collected private data without consent.
Protection: Use anti-spyware software and avoid downloading free programs from unreliable sources.

6. Adware

Adware automatically displays unwanted advertisements on the infected device, often leading to slow system performance.

How it Works: Adware typically comes bundled with free software or downloads. Once installed, it displays pop-up ads, banners, or redirects users to specific websites to generate ad revenue for attackers.
Example: Fireball was an adware malware that hijacked browsers and redirected users to malicious advertising sites.
Protection: Install reputable ad-blockers, and avoid downloading free programs from unknown sources.

7. Rootkits

Rootkits are among the most dangerous types of malware because they allow an attacker to gain unauthorized access to a system without being detected.

How it Works: Rootkits hide within system processes, modifying system files to remain undetected. Once installed, they can grant attackers access to the system, allowing them to manipulate files, steal data, and disable security features.
Example: Stuxnet was a sophisticated rootkit used to target Iran’s nuclear program, where it sabotaged industrial control systems while evading detection.
Protection: Use rootkit detection tools and ensure your system has robust security monitoring.

8. Keylogger

A keylogger records every keystroke made on a device, allowing attackers to capture sensitive information, such as passwords and credit card numbers.

How it Works: Keyloggers run in the background and can capture keystrokes from physical keyboards or virtual keyboards, sending the data back to the attacker.
Example: Zeus is a well-known banking Trojan that features keylogging functionality, which helped cybercriminals steal banking credentials from millions of users.
Protection: Use password managers, avoid using public Wi-Fi for financial transactions, and implement multi-factor authentication.

9. Fileless Malware

Unlike traditional malware, fileless malware doesn’t rely on files stored on the system to function. Instead, it runs directly in the computer’s memory, making it difficult to detect.

How it Works: Fileless malware often uses trusted system tools, such as PowerShell, to execute malicious scripts. Since it operates in memory, it doesn’t leave traces on the hard drive, making it harder for antivirus programs to detect.
Example: PowerShell-based malware attacks have become more common, exploiting the built-in capabilities of Windows to perform malicious actions without leaving a trace.
Protection: Use endpoint protection software and implement strict control over scripts and remote execution tools.

10. Scareware

Scareware tricks users into believing their computer has been infected or is in danger, prompting them to purchase fake antivirus software or services.

How it Works: Scareware presents fake alerts or pop-ups that appear to come from legitimate antivirus programs, scaring users into paying for unnecessary and often harmful software.
Example: Fake antivirus programs that tell users their systems are infected with malware and offer a “solution” in exchange for money.
Protection: Never trust unsolicited pop-ups or software that urges you to take immediate action. Always use reputable antivirus programs.

11. Backdoor Malware

Backdoor malware allows unauthorized access to a system by bypassing security mechanisms.

How it Works: Backdoors are typically installed by Trojans or other malware. They enable attackers to remotely control an infected device without the user’s knowledge or consent.
Example: DarkComet is a popular backdoor malware tool often used for remote surveillance and data exfiltration.
Protection: Use strong firewalls, ensure operating systems are updated, and scan for unauthorized processes regularly.

12. Botnet Malware

Botnet malware forms a network of infected devices, controlled by a central attacker. These networks can be used to conduct attacks such as DDoS (Distributed Denial of Service) attacks.

How it Works: Devices infected with botnet malware become “zombies” that can be remotely controlled to launch large-scale attacks on websites, often overwhelming them with traffic.
Example: Mirai was a botnet malware that turned insecure IoT devices into bots and used them to carry out massive DDoS attacks.
Protection: Secure all devices on your network, especially IoT devices, and monitor traffic for unusual spikes.

13. Wiper Malware

Wiper malware is designed to destroy or erase all data on a device, leaving it unusable.

How it Works: Wipers delete or corrupt files, making them unrecoverable. This type of malware can cause significant damage, especially if data backups are not in place.
Example: Shamoon is a wiper malware that targeted Saudi Arabian organizations in 2012, erasing data from tens of thousands of computers.
Protection: Regularly back up your data and use enterprise-grade security solutions.

14. Cryptojacking Malware

Cryptojacking uses an infected system’s resources to mine cryptocurrency, without the user’s consent.

How it Works: Cryptojacking scripts run in the background, using a computer’s CPU and power to mine cryptocurrencies for the attacker.
Example: Coinhive was a cryptojacking script that ran in the browser and mined Monero cryptocurrency without the user’s knowledge.
Protection: Block mining scripts with ad blockers, monitor CPU usage, and ensure web browsers have the latest security patches.

15. Fake AV Malware

Fake AV malware tricks users into believing they have a virus, prompting them to install fake antivirus software.

How it Works: The malware often presents alarming pop-up messages, warning users of infections and offering a “solution” in the form of fraudulent software that is either useless or malicious.
Example: WinFixer is a well-known fake antivirus program that falsely claimed to detect security issues and offered to fix them for a fee.
Protection: Never trust unsolicited warnings or software that promises immediate fixes for unspecified threats.

16. Dropper

A dropper is malware designed to deliver and install additional malicious files onto a system.

How it Works: Droppers execute when opened and then “drop” or install additional malware onto a victim’s computer. They often disguise themselves as legitimate software or files.
Example: Backdoor.Fraser is an example of a dropper that installs other malicious software to enable remote access to the infected system.
Protection: Avoid downloading software from unreliable sources and use endpoint protection software to detect droppers.

17. Downloader

Downloaders are similar to droppers but differ in that they fetch and execute additional malware from an online server, rather than installing it directly.

How it Works: The downloader malware sits on a device, silently fetching new threats from remote servers and executing them once they’re downloaded.
Example: Downloader.COVID was a downloader malware that fetched various payloads, including ransomware, during the height of the pandemic.
Protection: Ensure you have strong antivirus programs that monitor internet traffic and downloads, and don’t click on suspicious links.

18. Fleeceware

Fleeceware is a type of malware that tricks users into installing apps that appear legitimate but charge exorbitant fees for basic or useless features.

How it Works: Fleeceware apps typically offer a free trial or appear harmless but later impose recurring charges for very basic services or features that the user never intended to pay for.
Example: Several apps on Google Play Store, such as Balloons Pop or Camera Scanner, were found to be fleeceware after gaining user trust and charging hidden fees.
Protection: Always check app permissions and reviews before installing them, and never provide your payment information unless you trust the app.

19. MIME (Multipurpose Internet Mail Extensions) Malware

MIME malware uses email attachments disguised with legitimate MIME file types, like PDFs or images, to trick users into opening malicious files.

How it Works: These types of malware are often delivered via phishing emails that appear to be from trusted sources. Once the user opens the attachment, malware is executed.
Example: MIMECast was a known malware campaign using MIME-based attachments to distribute ransomware via email.
Protection: Always verify the legitimacy of emails and attachments before opening them. Use email filtering tools to block suspicious content.

20. Logic Bomb

A logic bomb is a type of malware that lies dormant until triggered by a specific event, such as a time, date, or specific action from the user.

How it Works: The malware remains inactive until a predefined condition is met, such as a specific date or system configuration, then activates to perform malicious actions like deleting data or disrupting system functionality.
Example: The Duqu malware used a logic bomb that was set to activate if a specific configuration file was opened on the target system.
Protection: Regularly monitor and audit system behaviors, and employ a robust backup strategy to prevent major damage if triggered.

21. Zombie

A zombie is a device that has been compromised and is now under the control of an attacker, often used in botnet attacks.

How it Works: Zombies are typically infected by Trojans or worms and used to launch attacks, like DDoS (Distributed Denial of Service) attacks, without the user’s knowledge.
Example: The Mirai Botnet turned over 600,000 devices into zombies, using them to launch massive DDoS attacks that targeted critical infrastructure.
Protection: Use firewalls, endpoint protection software, and avoid using insecure Internet of Things (IoT) devices that can easily be compromised.

22. Crypter

Crypters are malicious tools used to encrypt or obfuscate malware, making it harder for antivirus software to detect.

How it Works: Crypters disguise the true nature of a malware file by encrypting it or modifying its code. This allows the malware to bypass security tools and remain undetected until it’s too late.
Example: RATs (Remote Access Trojans) often use crypters to hide their malicious payload and avoid detection by security software.
Protection: Regularly update and patch your security software and operating systems to improve your defenses against crypters.

23. Hijacker

A browser hijacker redirects your web browser to unwanted websites or modifies your browser’s settings without your consent.

How it Works: This type of malware typically alters your homepage, search engine, or browser settings, forcing you to visit specific websites or display ads.
Example: MyWebSearch hijacked browsers and changed search settings, generating unwanted pop-ups and redirecting users to promotional websites.
Protection: Use trusted antivirus tools and avoid downloading free software that may contain bundled unwanted programs.

24. Internet of Things (IoT) Malware

IoT malware targets Internet of Things (IoT) devices, such as cameras, thermostats, and smart devices, often using them as part of a larger botnet or to launch attacks.

How it Works: IoT malware can infect smart devices by exploiting vulnerabilities, giving attackers access to control them for DDoS attacks or data exfiltration.
Example: Reaper malware targeted IoT devices, turning them into a botnet to carry out cyber-attacks.
Protection: Secure IoT devices with strong passwords, disable unnecessary features, and ensure they’re running the latest security patches.

25. Macro Virus

A macro virus infects documents or spreadsheets that contain macros, often through software like Microsoft Word or Excel.

How it Works: Macro viruses are usually embedded in documents with macros and activated when the user opens the file. They can cause data corruption or spread malware further.
Example: The Concept virus was one of the first macro viruses that spread via infected Word documents, wreaking havoc on office environments.
Protection: Disable macros in document settings, and be cautious when downloading files from untrusted sources.

26. Banking Trojan

A banking Trojan is a type of malware specifically designed to steal login credentials and financial information from banking applications or websites.

How it Works: Banking Trojans monitor your actions on banking websites and apps, stealing sensitive financial information such as usernames, passwords, and credit card details.
Example: Zeus is one of the most notorious banking Trojans, stealing sensitive data from banking customers and facilitating fraudulent transactions.
Protection: Enable multi-factor authentication (MFA) on all your banking accounts and avoid using public Wi-Fi for financial transactions.

27. Android Malware

Android malware targets devices running Android, the world’s most popular mobile operating system. These malware types can steal personal information, track user activity, and hijack apps.

How it Works: Android malware typically spreads via infected apps, fake updates, or malicious links. Once installed, it can monitor the user’s activity or use the device for other malicious purposes.
Example: Joker malware, a notorious Android malware, subscribed users to premium services without their knowledge and sent their sensitive data to remote servers.
Protection: Always download apps from the official Google Play Store, and use mobile security software.

28. File Infector Virus

A file infector virus specifically targets executable files, infecting them and causing the system to execute the malicious code whenever the infected file is opened.

How it Works: The file infector virus attaches itself to executable files and spreads when those files are opened or run, often causing the program to crash or behave abnormally.
Example: Cascade, a famous file infector virus, spread by infecting executable files and causing system instability.
Protection: Keep file extensions visible, monitor your files for unusual changes, and avoid running files from untrusted sources.

29. SMS Trojan

An SMS Trojan is malware that sends premium-rate text messages to other phones or services without the user’s consent.

How it Works: The SMS Trojan infects a device, and once activated, it sends SMS messages to premium-rate services, generating revenue for the attacker.
Example: Trojan-SMS.AndroidOS.FakeInst is a known example, which used SMS Trojans to sign users up for expensive services.
Protection: Keep your mobile devices updated, and only install apps from trusted sources.

30. Firmware Malware

Firmware malware targets the firmware (low-level software) of a device, such as a router or a hard drive, to compromise the hardware itself.

How it Works: Firmware malware typically requires physical access or a sophisticated exploit to install on devices. Once installed, it can render the hardware unusable or provide persistent access to attackers.
Example: BadUSB is a firmware attack that turns USB devices into malware-delivery systems, infecting the hardware with malicious code.
Protection: Use hardware-based security, update firmware regularly, and employ physical access control to prevent these attacks.

31. Polymorphic Malware

Polymorphic malware changes its code every time it infects a new system, making it difficult for signature-based security systems to detect.

How it Works: Polymorphic malware encrypts itself or modifies its code upon infection, allowing it to avoid detection by traditional antivirus solutions.
Example: Storm Worm is an example of polymorphic malware that continually changes its code to stay ahead of security measures.
Protection: Use heuristic and behavior-based detection tools to identify polymorphic threats.

32. Rootkit Trojan

A rootkit Trojan is a malware designed to provide attackers with root-level access to a device while hiding its presence.

How it Works: Rootkits can be installed on a system through malware or exploits, and they remain stealthy to avoid detection. Once installed, they give attackers deep access to the system, allowing them to modify files and even control the device remotely.
Example: TDSS Rootkit was a notorious malware that used rootkit technology to hide itself and steal sensitive data.
Protection: Regularly update operating systems, use security tools that detect rootkits, and employ firewall solutions to block unauthorized connections.

33. Fake Antivirus Malware

Fake antivirus malware tricks users into believing their computer is infected, prompting them to download fake antivirus software that actually contains malware.

How it Works: The fake antivirus software alerts the user about supposed infections, encouraging them to download and pay for a fake program that only infects their computer further with additional malware.
Example: Rogue antivirus software like Antivirus 2009 misled users into purchasing fraudulent software that didn’t provide any real protection but actually installed additional threats.
Protection: Only download software from trusted sources, and ensure your antivirus software is always up to date.

34. Backdoor

A backdoor is a type of malware that allows cybercriminals to gain unauthorized access to a system, bypassing security mechanisms.

How it Works: Once installed, backdoor malware enables attackers to remotely access the infected system, often used for further exploitation or data theft. Backdoors can be installed through phishing, exploits, or Trojan horses.
Example: The DarkComet RAT is a well-known backdoor trojan that allows attackers to access and control an infected system.
Protection: Regularly update software and use advanced endpoint protection software to detect backdoors. Also, avoid interacting with suspicious emails and links.

35. Remote Access Trojan (RAT)

A Remote Access Trojan (RAT) gives an attacker control over a device remotely, allowing them to steal data, monitor activities, or execute commands.

How it Works: RATs often disguise themselves as legitimate software or attachments. Once installed, they open a channel for attackers to control the system remotely, capturing keystrokes, screenshots, or even activating the camera.
Example: njRAT is a popular RAT malware that allows attackers to remotely control infected systems.
Protection: Use firewall and antivirus software that can detect RATs and monitor network traffic for unusual activity.

36. Ransomware-as-a-Service (RaaS)

Ransomware-as-a-Service (RaaS) allows anyone, including non-technical users, to launch ransomware attacks by renting malware for a fee.

How it Works: The creators of RaaS provide a platform where attackers can customize and deploy ransomware attacks, often in exchange for a share of the ransom payments.
Example: REvil (Sodinokibi) is a well-known RaaS platform, where affiliates can customize and launch ransomware attacks on victims.
Protection: Always back up important files, avoid suspicious links, and use anti-ransomware solutions that monitor suspicious file encryption behavior.

37. Polymorphic Virus

A polymorphic virus changes its code or appearance each time it infects a new system, making it harder to detect by signature-based antivirus tools.

How it Works: When the virus infects a new system, it mutates its code or obfuscates itself, thus avoiding detection by traditional security software. It spreads similarly to regular viruses but remains difficult to track.
Example: The Storm Worm is an example of a polymorphic virus that continuously changed its code to evade detection.
Protection: Use behavior-based security tools that analyze the actions of files and processes, rather than relying solely on signatures.

38. Exploit Kit Malware

Exploit kits are tools used by cybercriminals to exploit vulnerabilities in software applications and deliver malware.

How it Works: Once an exploit kit identifies a vulnerability in the victim’s software (like a browser or Flash Player), it automatically delivers malicious code that installs malware on the system.
Example: Angler Exploit Kit was one of the most popular exploit kits used to deliver ransomware and banking Trojans.
Protection: Keep software updated and patched, and employ web application firewalls to protect against exploit kit infections.

39. ATM Malware

ATM malware targets ATMs (Automated Teller Machines) to steal sensitive card information, including PIN codes and bank account details.

How it Works: ATM malware is often installed on compromised ATM systems, allowing attackers to collect card data by skimming, or even manipulate the ATM to dispense cash fraudulently.
Example: GreenDispenser is a type of ATM malware that allows cybercriminals to hijack the operation of ATMs, instructing them to dispense cash or gather card information.
Protection: Banks and financial institutions can secure ATMs by using updated antivirus software and ensuring that ATM software is regularly patched and monitored.

40. Infostealer

An Infostealer is a type of malware designed specifically to steal sensitive information from infected systems, such as login credentials, credit card numbers, and banking details.

How it Works: Infostealers target and extract stored information from browsers, email clients, or even desktop applications. The collected data is sent back to attackers for exploitation or sale on the dark web.
Example: Emotet is a well-known infostealer that primarily targets email communication and banking credentials.
Protection: Use multi-factor authentication, update passwords regularly, and employ endpoint protection solutions to block the theft of personal information.

41. Time Bomb

A Time Bomb is a type of malware that remains dormant until a certain date or event triggers its malicious activity.

How it Works: Time bombs are programmed to execute their payload after a certain amount of time has passed or after a specific condition is met (such as an anniversary, system error, or system shutdown).
Example: Chernobyl virus was a time bomb malware that activated on April 26, the anniversary of the Chernobyl disaster, causing system crashes and data loss.
Protection: Ensure that antivirus software is running and regularly updated to scan for malware with time-triggered behaviors. Frequent system backups also help mitigate damage.

42. Mail Bombing

Mail bombing refers to the use of large volumes of emails, often containing malicious attachments, sent to overwhelm a victim’s inbox or email server.

How it Works: By sending an overwhelming number of emails, the attacker can flood the victim’s inbox, causing denial-of-service (DoS) issues or even crashing the email server. The emails may also contain malware attachments or phishing links.
Example: The 1997 Microsoft email bomb attack targeted Microsoft’s email servers by sending thousands of emails, blocking legitimate communications.
Protection: Implement robust spam filters, email validation, and system defenses against DoS attacks to mitigate the impact of mail bombing.

43. Zombie Malware

Zombie malware refers to infected computers that become part of a botnet, which is a network of compromised systems controlled remotely by an attacker.

How it Works: Once a device is infected with zombie malware, it is turned into a “zombie” or “bot” and can be remotely controlled by the attacker to carry out malicious activities such as launching DDoS attacks or sending spam.
Example: The Mirai botnet turned IoT devices into zombies and used them in massive DDoS attacks that took down major websites like Twitter and Reddit.
Protection: Use firewalls and security tools to detect botnet activity and prevent devices from becoming infected with zombie malware.

44. Eavesdropping Malware

Eavesdropping malware listens in on communications between devices, such as voice or video calls, and captures sensitive information.

How it Works: Once installed, eavesdropping malware monitors incoming and outgoing communications, which could include email, messages, or voice calls, and transmits the data to the attacker.
Example: FlexiSpy is an example of surveillance software used for eavesdropping and spying on communication data, often used by attackers to gather sensitive details.
Protection: Encrypt communications and use strong security protocols like SSL/TLS for internet connections to protect data from eavesdropping.

45. Social Media Malware

Social media malware exploits the popularity of social media platforms to spread malicious links or content that leads to malware infections.

How it Works: Attackers post infected links or attachments disguised as something interesting or engaging (like a funny video) on social media platforms. Users who click the links inadvertently download malware.
Example: Koobface is a social media malware that spread via Facebook and MySpace by enticing users to click on infected links that led to social engineering attacks.
Protection: Be cautious when clicking on links from unknown users, and use social media security features to block or report suspicious accounts.

46. Minespoiler

Minespoiler is a type of malware that silently hijacks a system’s processing power to mine cryptocurrency without the user’s consent.

How it Works: This malware infects systems and runs in the background, using the CPU to mine cryptocurrencies like Bitcoin or Monero. The attacker profits from the computing power of infected devices.
Example: Coinhive was a popular JavaScript-based miner that ran in users’ browsers to mine Monero, often without their knowledge.
Protection: Ensure that your devices are protected by ad blockers and monitor system performance for any unusual spikes in CPU usage.

47. Hacktivist Malware

Hacktivist malware is used by cybercriminals who have political or ideological motivations, often to disrupt government, corporate, or other organizations they disagree with.

How it Works: Hacktivists deploy malware to steal sensitive information, bring down websites, or cause general chaos as part of a broader political or social agenda.
Example: The Anonymous hacking group has used a variety of malware to target governments, corporations, and other organizations for political activism.
Protection: Implement strong cybersecurity protocols, including firewalls and intrusion detection systems, to defend against politically motivated malware attacks.

48. Malvertising

Malvertising involves embedding malicious code into advertisements on legitimate websites, which users unknowingly click on, leading to malware infections.

How it Works: Malvertising typically uses malicious online ads to spread malware, often through JavaScript. When users click on these ads, they may be redirected to a site that exploits vulnerabilities or directly downloads malware.
Example: The Angler Exploit Kit used malvertising to distribute ransomware and other types of malware by embedding malicious ads on trusted websites.
Protection: Use ad blockers, ensure that your web browser and plugins are up-to-date, and be cautious about clicking on advertisements online.

49. Keylogger Malware

Keylogger malware is a type of surveillance tool that records every keystroke made by the user, including login credentials, credit card numbers, and other sensitive information.

How it Works: Keyloggers can be installed through phishing emails, malicious downloads, or via other malware types. They track every keystroke and send this data back to attackers.
Example: Spybot is an example of a keylogger that can monitor user activity, including usernames and passwords, making it a popular tool for cybercriminals.
Protection: Use strong passwords, implement two-factor authentication, and use anti-keylogging software to detect and block keyloggers.

50. Bootkit

A Bootkit is a type of malware that infects the boot sector of a computer’s hard drive, which is the part of the system that loads the operating system during startup.

How it Works: Bootkits can alter the boot sequence to load malicious software before the operating system is even loaded, making it difficult to detect by traditional antivirus programs.
Example: Mebroot is a famous bootkit that alters the Master Boot Record (MBR) of a system to gain persistent access.
Protection: Use secure boot settings, install trusted antivirus software that can detect boot-level malware, and keep your system firmware updated.

51x. Destructive Malware

Destructive malware is designed to cause harm to a system or network, often by deleting files, damaging data, or rendering systems inoperable.

How it Works: Destructive malware can wipe out data, overwrite system files, and cause irreversible damage to hardware or software. It can be deployed in both targeted and indiscriminate attacks.
Example: Shamoon is an example of destructive malware that targeted energy companies, wiping data and rendering systems useless.
Protection: Regularly back up important files, and use malware detection software to identify destructive threats before they cause significant damage.