The 10 categories of malware you need to know about to protect your business from cyberthreats
Do you want to protect yourself against the risks of computer attacks? The first barrier is knowledge. As Sun Tzu said in The Art of War: "to win, you must know your enemy".
This maxim also applies to virtual conflicts! That's why we've put together a comprehensive guide to everything you need to know about malware. The main categories of malware, new forms to watch out for in 2025, good security practices, anti-malware software... We take you through it all in detail.
Definition of malware: what you need to understand
What is malware?
Let's go back to basics: what is malware? Malware is software designed to harm the endpoints of a network system. From disrupting operation to damaging files, cybercriminals impose different missions on their malicious code, depending on the objectives to be achieved.
What are the objectives of malware?
As is often the case when it comes to criminal activities, the main motivation is the lure of profit. Bank data theft, blackmail using ransomware... There are many ways of monetising computer attacks. And there's no denying it: cybercriminals are pretty creative! 🙃
Malware is also often used for espionage purposes. Governments, competing companies or the merely curious seek access to your personal or professional information for all sorts of nefarious reasons.
Finally, it may sound crazy, but some malware is aimed purely at destruction. Deleting files, paralysing systems... These attacks seek only to cause harm without making any profit from the attack.
What are the risks associated with malware?
The consequences of an infection can be disastrous for your business.
- Firstly, financially: theft of money, bank fraud, or the cost of restoring systems. The bill can quickly soar.
- Your privacy is also at risk from identity theft, blackmail and surveillance of your online activities. Your personal data is extremely valuable and must not fall into the wrong hands!
- Operational risks are particularly acute for corporate IT systems. Loss of important files, data corruption, paralysis of your business... Malware can quickly turn your daily digital life into a nightmare.
What are the two categories of malware?
Passive malware
This type of malware acts discreetly, which is why it is so dangerous. 😶🌫️
Their main objective? To remain invisible for as long as possible in order to collect sensitive information. They install themselves silently and observe your habits, sometimes for months. Because they don't disrupt your system, you don't notice a thing.
Active malware
Active malware, on the other hand, does not seek discretion. They act, without hiding, to do maximum damage or make maximum profits. This category includes ransomware that encrypts your sensitive files and worms that saturate your networks.
Their main weapon? Speed of action. They can cause irreversible damage in just a few minutes.
The 10 best-known categories of malware
1- Viruses
Viruses are the most common type of malware. It is malicious code that is inserted into an application and runs alongside it. It then infects the network system to steal data or launch DDoS or ransomware attacks. The virus is therefore generally the first link in a more global malware attack. Its concealment within an application makes it a particularly dangerous threat.
Case in point:
In 2000, a virus spread via e-mail attachments. It included the subject line "I Love You" and infected millions of computers, destroying all their data.
2- The computer worm
The worm infiltrates networks through vulnerabilities in operating systems. It has two major characteristics: it requires human interaction to spread and then replicates itself, without any intervention.
Case study :
Discovered in 2010, and probably developed by US intelligence services, Stuxnet was introduced into Iran using a USB key. The aim? To thwart the smooth operation of Iran's uranium enrichment centrifuges in order to slow down their nuclear programme.
The creator, Sylvqin, told this story on video a few months ago on his YouTube channel:
3- Trojans
Trojans disguise themselves as legitimate software to fool users. Once installed, they open a back door in your system for cybercriminals. 🐎 Unlike viruses, they do not replicate, but remain permanently hidden. They are often used as a launch pad for other, more sophisticated attacks.
Case in point:
In 2016, the Emotet trojan spread via fake bank emails. It stole millions of login credentials before acting as a gateway to deploy other malware on infected systems.
4- Ransomware
Ransomware encrypts your files and demands a ransom to unlock them. Ransomware is a company's nightmare, because it can completely paralyse a business in a matter of hours. Cybercriminals particularly target critical data to maximise the pressure. But beware: paying does not guarantee the recovery of your files!
Case in point:
WannaCry infected more than 300,000 computers in 150 countries in 2017. Hospitals, businesses, government departments... Everything came to a standstill for days, causing millions of euros worth of damage.
✅ Fortunately, solutions exist to protect you:
5- Spyware
Spyware (or spyware 🕵️) discreetly monitors your digital activities. Web browsing, passwords, conversations... it does it all. It then transmits this data to malicious third parties. Particularly vicious, it can even activate your webcam or microphone without your knowledge. A total violation of your privacy.
Case in point:
The Pegasus spyware was used to spy on journalists and activists around the world. It could access messages, photos and even locate victims in real time.
✅ Here too, we've got your back: we've prepared a comparative article on the best antispyware!
6- Adware
Adware bombards your screen with unwanted ads to redirect you to malicious sites. The aim is to generate illegal advertising revenue by diverting users' browsing. Although apparently less dangerous, adware considerably slows down your systems and can serve as a gateway for other malware. Sound familiar? We hope not...
Case in point:
Superfish was pre-installed on Lenovo computers and injected adverts into every web page visited. Although based on a legal economic system, Superfish exposed users to man-in-the-middle (MITM) attacks.
7- The keylogger
The keylogger (or keylogger) is software that collects all your keystrokes, and therefore your passwords and banking information. It works in the background, completely invisibly. Cybercriminals then use this data to steal your identity or empty your accounts. If your smartphone slows down or someone tries to connect to your accounts, this could be the sign of an attack of this type.
Case in point:
The Zeus keylogger stole millions of bank details between 2007 and 2010.
8 and 9- Rootkits and bootkits
Rootkits install themselves at the heart of your operating system to take complete control of it. They modify the computer's essential functions and become virtually undetectable. The benefits to the cybercriminal are manifold. They can make the resources of the victim system available and even use it as a starting point for other attacks of the same type. Of course, they also gain access to your personal data.
Bootkits are like rootkits, but go even further. They are activated at start-up, even before the operating system. Once in place, they can install any other malware.
Case in point:
The Flame rootkit was so sophisticated that it went undetected for years in the Middle East. It could record conversations, take screenshots and even self-destruct to erase its tracks.
10- Botnets
A botnet turns your computer into a "zombie" controlled remotely by cybercriminals. Your machine then becomes part of a network of thousands of infected computers used for massive attacks (DDoS, spam, cryptocurrency mining, etc.). And of course, you don't realise a thing. 🧟
Case in point:
The Conficker botnet infected over 9 million computers worldwide. It was used to distribute other malware and generate illegal advertising revenue, making millions of dollars for its creators.
4 new forms of malware to watch out for in 2025
As the performance of anti-malware software increases, cybercriminals are developing new threats. Yes, they're innovative too, unfortunately for us! Here are the 4 new malware trends for 2025.
1- Malware-as-a-Service (MaaS)
The MaaS principle takes the SaaS (Software-as-a-Service) business model and adapts it to the criminal world of malware.
👉 In practical terms, MaaS gives attackers access to complete hacking tools without the need for any particular technical skills. They access the dark net to buy complete ransomware or phishing suites to carry out their malicious activities.
2- AI and autonomous malware
Artificial intelligence is revolutionising all sectors, and the world of malware is no exception. The specificity of these new programmes is that they automatically adapt to the defences they encounter.
👉 No need for human intervention: they choose their targets, modify their code and launch their attacks completely autonomously.
3- Targeted attacks on IoT and mobiles
Connected objects and smartphones are becoming the new targets of choice for cybercriminals. Surveillance cameras, smart thermostats and connected watches can be hacked as soon as they are linked to a network. These devices are particularly vulnerable because their security is weak and they are rarely updated.
4- Deepfakes and automated social engineering
Deepfakes can now be used to create ultra-realistic fake videos capable of fooling anyone. These automated social engineering techniques use AI to create personalised voices, faces and messages.
In 2025, we had a good example of this type of attack with a very realistic fake Brad Pitt who bilked his victim out of more than €300,000 in France.
How can we detect and protect ourselves from the different categories of malware?
Protection against malware involves two fundamental approaches: human vigilance and technological protection. Here's how to combine these two approaches within your company.
Our advice
Tip 1: Make your team aware of cybersecurity
The first step towards effective cybersecurity is to make your teams aware of good IT practices. All members of the company need to be trained in the main dangers they are likely to encounter on a daily basis. For example, after-sales service staff who receive a lot of emails need to be very alert to the signs of a phishing attempt. Managers, on the other hand, should be particularly wary of whaling. Every level of the company should benefit from appropriate cyber training.
Tip 2: Update systems regularly
Updates are a way for software publishers to develop the functionality of their products, but not the only one. Updates also allow security flaws identified in the previous version to be plugged. In the end, this is the only benefit of malware attacks. Offering insights into the new trends of cybercriminals to better protect software.
Tip 3: Reinforced identification
Two-factor authentication has become essential in the face of new malware. Thanks to this additional security, even if your passwords are compromised, cybercriminals will not be able to access your critical systems. This type of authentication can take several forms: biometrics, physical tokens, SMS codes, etc. Multiply the locks.
Tip 4: Continuous monitoring
Monitoring is absolutely essential for effective digital protection. Constantly monitor your systems to detect any abnormal behaviour on your network. Look out for the following signs: unexplained slowdowns, unusual connections or data transfers. The sooner you detect an intrusion, the less damage there will be.
Tip 5: Zero-trust strategy
Don't trust anyone, even inside your network. Every user and every device must be checked before accessing resources. By partitioning your systems as much as possible, you can limit the spread of malware in the event of an attack.
The 5 essential anti-malware tools
5 anti-malware tools stand out on the market for protecting your systems against malware. For each product, we give you its main features and price.
1 of 5
 EventLog Analyzer |  Avast Premium Business Security |  GravityZone by Bitdefender |  Malwarebytes |  Norton 360 |
|---|---|---|---|---|
| For companies with more than 1 employees | For all companies | For all companies | For all companies | For all companies |
| See software | See software | See software | See software | See software |
| Learn more about EventLog Analyzer | Learn more about Avast Premium Business Security | Learn more about GravityZone by Bitdefender | Learn more about Malwarebytes | Learn more about Norton 360 |
Avast Essential Business Security
Avast Essential Business Security is designed for VSEs and SMEs. Thanks to this solution, all your company's workstations are protected against the main threats.
When you install Avast, you get the following features:
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A firewall to protect against encryption, data leakage and online confidentiality.
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Phishing detection tools.
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Protection against the main malware and spyware.
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AI technology to detect infected files and zero-day threats.
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A management platform to control your security on the move.
Avast Essential Business Security is available from €28.26 per device per year. The free trial period is 30 days.
Avast Premium Business Security
GravityZone Small Business Security (Bitdefender)
GravityZone Small Business Security offers enterprise-level protection for small businesses. Its key feature is its modularity, which means you can upgrade your security as your business grows.
GravityZone Small Business Security includes :
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Multilayered protection using machine learning and behavioural analysis.
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Advanced ransomware prevention with automatic recovery.
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Protection against zero-day attacks.
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Anti-phishing and online fraud detection.
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A centralised console for easy management of all your endpoints.
GravityZone Small Business Security is available from €227.49 per year for 10 workstations.
GravityZone by Bitdefender
Malwarebytes
Malwarebytes is a cybersecurity solution that stands out for its ease of use. It is designed for entrepreneurs and small businesses without technical skills.
It features multi-layered AI-powered technology to ensure real-time protection against the latest cyber threats. A particularly powerful defence against viruses, spyware, brute force attacks and ransomware.
In terms of system performance, Malwarebytes is also four times faster.
The Malwarebytes Teams version was voted product of the year by AV Lab, a testament to its quality.
Malwarebytes Team is available from €110.99 per year for 3 devices.
Malwarebytes
ManageEngine EventLog Analyzer
ManageEngine EventLog Analyzer is an advanced monitoring platform dedicated to real-time threat detection. With ManageEngine EventLog Analyzer, you can continuously analyse your system logs to identify suspicious behaviour.
The tool incorporates :
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AI-powered behavioural monitoring.
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Alerts for malicious activity or breach attempts.
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Automated compliance reports to meet regulatory requirements.
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A centralised interface for managing your network security.
ManageEngine EventLog Analyzer is available from €0 per year for 5 log sources. However, for more professional use, we recommend the $595 Premium package, which allows you to analyse from 10 to 1,000 log sources.
EventLog Analyzer
Norton 360
Norton 360 is cybersecurity software for both the self-employed and private users. It also provides effective protection for your business and personal devices thanks to its ease of use.
Norton 360 combines multi-layered protection against malware, ransomware and zero-day attacks.
It also includes a secure VPN to guarantee the confidentiality of your connections, even when you're on the move or teleworking.
The native password manager facilitates strong authentication, while automatic cloud backup ensures that your critical data is preserved.
As an added bonus, Norton 360 regularly monitors the dark web to alert you if sensitive information is being leaked.
All this is available from £49.99 per year for coverage of three devices, including 10GB of cloud storage.
Norton 360
In a nutshell: a better understanding of malware categories means better protection for your business
You now know a little more about the main categories of malware and their associated risks. Knowledge is the basis for a real cybersecurity strategy. Educating your teams about good security practices, integrating anti-malware solutions, keeping abreast of the latest trends in cyber threats... Adopt a proactive approach to maximise your protection against malicious software.
Article translated from French
Maëlys De Santis, Growth Managing Editor, started at Appvizer in 2017 as Copywriter & Content Manager. Her career at Appvizer is distinguished by her in-depth expertise in content strategy and marketing, as well as SEO optimization. With a Master's degree in Intercultural Communication and Translation from ISIT, Maëlys also studied languages and English at the University of Surrey. She has shared her expertise in publications such as Le Point and Digital CMO. She contributes to the organization of the global SaaS event, B2B Rocks, where she took part in the opening keynote in 2023 and 2024.
An anecdote about Maëlys? She has a (not so) secret passion for fancy socks, Christmas, baking and her cat Gary. 🐈⬛