Which Operating System Is the Most Secure? macOS, Windows, Linux, Red Hat, Fedora or HarmonyOS?

If I had a pound for every time someone asked me which operating system is the most secure, I could probably quit my job and start farming alpacas. Or buy another laptop. I am honestly not sure which option would be more sensible.

Since I try to keep my word and answer the questions that come up most often, I decided to take this topic seriously.

And I can already hear some people picking up stones.

For some, the answer is Linux. For others, it is macOS, because Apple controls both the hardware and the software. Someone else will say Windows, but only if it is properly secured and managed. Another person will point to Red Hat Enterprise Linux because of enterprise support, SELinux and long-term stability. Someone else will choose Fedora because it is modern, fast and technical. And now we also have HarmonyOS, another ecosystem trying to build its own approach to devices, applications and security.

In other words, a classic internet IT discussion: lots of emotions, lots of opinions and, sometimes, even a few facts.

The problem is that asking “which operating system is the most secure?” is a bit like asking: which car is the best?

Well, best for what? Formula 1 racing? Carrying bricks? Office work? Gaming at the weekend? Or taking the kids to school when the back seat already looks like a science experiment involving apple juice?

Operating systems are similar.

There is no single most secure operating system for everyone. The system should be chosen based on the need: office work, warehouse operations, home use, gaming, IT administration or servers. Security does not depend only on the logo on the boot screen. It depends on updates, configuration, hardware, applications, encryption, management, the user and whether someone still thinks that admin123 is a strong password.

Security Is Not Just a Logo

People often judge the security of an operating system by its reputation. macOS is seen as secure. Linux is seen as technical and resilient. Windows is seen as frequently attacked. Red Hat is seen as professional and enterprise-ready. Fedora is seen as modern. HarmonyOS is seen as a fresh and controlled ecosystem.

But in practice, operating system security has many layers. A bit like an onion, or like someone wearing three jumpers in winter because “there might be a draught”.

What matters includes:

• how quickly the vendor provides security patches,
• whether the system has a reliable and predictable update mechanism,
• whether the user works as a local administrator or with a standard account,
• whether the disk is encrypted,
• whether the system supports Secure Boot, TPM or similar boot protection mechanisms,
• whether applications are isolated,
• where the user installs applications from — an official source or a file called free_photoshop_keys.exe,
• whether the company can manage the device through MDM, RMM, Intune or similar tools,
• whether events can be monitored and incidents can be investigated,
• whether administrators have the knowledge to maintain the system properly, rather than just pressing Enter and hoping for a miracle.

And for a normal person: MDM, RMM and Intune are names of robots from Star Wars. They are tools that allow a company to manage computers, phones, updates and security. GPO is like a company rulebook for domain-joined computers: what is allowed, what is blocked and why someone from accounts should not install a “super invoice tool” from a suspicious website. And SELinux is an additional guard in Linux that can say: “No, my friend, you are not doing that” — even when someone thinks that being root means they can do absolutely anything.

A system can be technically very secure, but if it is poorly configured, not updated or used without control, it quickly loses its advantage.

A simple example: Linux with SSH open to the internet, a weak password and no updates is not secure just because it is Linux. That is like saying: “I have a safe, but the key is under the doormat and the code is 0000.” macOS used every day with an administrator account and random applications downloaded from the internet is not magically immune either. Windows without BitLocker, updates, MFA and application control will also be an easy target.

Even the best operating system and MFA will not help much if someone uses the same password for their laptop, email, Facebook and a mushroom shop.

So the better question is not: which system is the most secure?

The better question is: which system is the best and most secure for a specific use case?

The Operating System Should Match the Need

This is one of the most important points. An operating system should not be chosen based on emotions, fashion or opinions from the internet. It should be chosen based on real work.

An office worker has different needs. They may mostly use Microsoft 365, Outlook, Teams, SharePoint, a browser, company printers and business applications. In that environment, Windows is often the most practical choice, because it integrates well with Active Directory, Entra ID, Intune, Microsoft 365, printers and common business software. macOS can also be an excellent choice, but only if the company can manage it through MDM and the required applications are compatible. Otherwise, you end up with “that one Mac in marketing” that nobody can connect to the printer.

A warehouse has different requirements. Stability, simplicity and compatibility matter more than looking modern. The system must work with ERP software, barcode scanners, label printers, terminals and other peripherals. Nobody in a warehouse wants to hear: “I just need to reboot your computer because I have a new kernel.” The scanner needs to work, labels need to print and the ERP system should not start crying.

Gaming is different again. For gamers, the most important things are GPU drivers, performance, game compatibility, platforms such as Steam, Epic Games or Battle.net, and support for controllers and peripherals. In this area, Windows is still usually the most practical choice. Linux and SteamOS are improving a lot, but compatibility is not always the same as on Windows. And before someone shouts “I have been gaming on Linux for five years!” — great, but not everyone wants to spend the weekend configuring Wine, Proton and launch flags.

For a home user, security usually means regular updates, simple operation, a good browser, encryption, backup and protection against phishing. For one person, Windows will be the best option. For another, macOS. For a more technical user, Linux. And that is perfectly fine — as long as the system fits the person, rather than forcing the person to suffer because someone online said “this is more secure”.

An IT administrator has different needs again. They need SSH, RDP, PowerShell, a terminal, VPN, diagnostic tools, virtualization, log analysis, configuration testing, server management and the ability to work across multiple systems. For an administrator, the best answer is often not one system, but a combination: Windows for Microsoft 365, Active Directory, Entra ID, Intune and corporate tools; Linux for servers, terminal work, automation and diagnostics; sometimes macOS as a stable workstation with a good terminal and comfortable workflow. Or simply three laptops and coffee.

And then there is the non-technical user who does not want to know the difference between a kernel, a driver and a security policy. They want to open email, print a document and avoid becoming the main character in the company’s next security incident. For that person, the best system is simple, up to date, managed and able to block bad decisions before the user clicks them.

Hardware Matters Too

You can choose the most secure operating system in the world, but if the hardware cannot cope, security will quickly start losing against user frustration.

Windows 11 on a very weak computer? It may boot, but after a few updates, an antivirus scan and opening a browser, the user may start searching for ways to “speed up the system”. And the first “tip from the internet” is often to disable security features. That is when things become interesting — but not in a good way.

macOS on old, unsupported hardware may still look nice, but the lack of security updates is a real risk. Linux can give an older laptop a second life, but you need to choose the right distribution and desktop environment. GNOME on a computer with 2 GB of RAM is a bit like trying to pull a caravan with a bicycle.

RAM, SSD, TPM, Secure Boot, drivers and vendor support all matter. First check the hardware, then choose the operating system. Not the other way around.

This does not mean that everyone needs the most expensive device. It means you should not install a system that really needs 8 GB of RAM on a computer with 2 GB, and then complain that “the system is slow”. Sometimes the operating system is not the problem. Sometimes the hardware is simply asking for retirement.

A Quick Look at Popular Operating Systems

macOS – Very Good, but Not Magic

macOS has many strengths. Apple controls both the hardware and software, which helps integrate the system, updates and security features. macOS includes mechanisms such as FileVault, Gatekeeper, System Integrity Protection, application permission controls and good support for management through MDM.

In business environments, macOS can be an excellent choice, especially for creative teams, managers, developers and users working within the Apple ecosystem. A well-managed Mac with encryption, updates, MDM and a standard user account can be a very secure device.

But macOS is not a magic shield. You can still install a malicious application, fall for phishing, misconfigure permissions or ignore updates. The Apple logo does not replace backups, strong passwords and common sense.

Windows – The Biggest Target, but Not Automatically the Weakest

Windows often has a reputation for being less secure, but that view is not always fair. Windows is attacked so often because it is extremely common in businesses and on user computers. For cybercriminals, it is simply the biggest target — like a large supermarket car park. If everyone parks there, thieves have more choice.

That does not mean modern Windows is technically weak. A modern version of Windows, properly supported, updated and managed, can be a very solid platform. BitLocker, TPM, Secure Boot, Microsoft Defender, Defender for Endpoint, Credential Guard, Application Control, Intune, Entra ID, MFA and security policies provide strong protection options.

The problem with Windows is often not the system itself, but the environment around it: local administrators, old applications, missing updates, weak passwords, no MFA, no encryption, old printers, badly configured GPO, users clicking everything that moves and companies without a proper device management process.

A well-managed Windows environment can be more secure than a badly managed Linux or macOS environment. But it needs to be maintained properly.

Linux – Great Control, Greater Responsibility

Linux is often considered secure, and in many cases that is true. It is widely used on servers, in the cloud, in containers, on network devices and in technical environments. It gives strong control, powerful administration tools, a solid permission model and huge flexibility.

But “Linux” is not one system. Fedora, Ubuntu, Debian, Arch, Red Hat Enterprise Linux, AlmaLinux, Rocky Linux, openSUSE and other distributions differ in update cycles, stability, support, default configuration, repositories and purpose.

Linux gives administrators a lot of power. But more power also means more responsibility. You can build a very secure Linux server. You can also build a very insecure Linux server if you do not understand firewalls, SSH, updates, permissions, logs and hardening.

It is an excellent system for technical users, but not always the best choice for every end user. When something breaks, the answer “read the manual” does not always work on an angry director.

And by the way — I know Linux can run for months without a reboot. I have seen servers with an uptime longer than some marriages. But do you really want a system that has not rebooted since people were still burning DVDs? Sometimes a reboot is not a shame. Sometimes it is hygiene.

Fedora and Red Hat Enterprise Linux – Two Different Worlds

Fedora and Red Hat Enterprise Linux are a good example of why even in the Linux world there is no single answer.

Fedora is modern, dynamic and technical. It offers fresh technologies, newer kernels, fast updates and SELinux enabled by default. It is a good choice for developers, administrators, Linux enthusiasts and users who want new features earlier than they appear in enterprise systems.

Red Hat Enterprise Linux takes a different approach. It is not about having everything newest. It is about stability, predictability, long-term support, certifications, documentation and vendor support. It is also about letting the compliance department sleep at night.

Fedora is more like a fast testing workshop. RHEL is more like a production machine that is expected to run calmly for years. Both approaches make sense, just in different places.

HarmonyOS – A New Ecosystem and New Questions

HarmonyOS is an interesting example because it shows that the operating system market is still changing. Huawei is building its own ecosystem designed to work across different device types: phones, tablets, laptops, smart devices, cars and other connected environments.

From a security perspective, HarmonyOS is interesting because a new ecosystem can be designed with greater control over applications, devices and integration. But as with any new system, the right questions are important: how transparent is it? How are updates delivered? Are there independent audits? How mature is management? How compatible are the applications? How does it perform in real business use?

New does not automatically mean more secure. Sometimes it simply means: “let’s check before we get too excited.” HarmonyOS sounds a bit like the name of a face cream or a planet from science fiction. Maybe it really works well. But until we see more about real support, updates and day-to-day compatibility, I remain in “interesting, but calm” mode.

Popularity and Number of Attacks

It is also worth remembering that the number of attacks against a system does not always mean the system is technically the worst. Often it simply means it is the most profitable target — like a bank on the corner, not a small kiosk down the street.

Windows is a huge target because it is widely used in business. Android is a huge target because it runs on a massive number of mobile devices. macOS is increasingly attacked as it becomes more common in companies and among business users. Linux is attacked heavily on servers, cloud platforms, containers and internet-facing services.

Attackers go where the data, money, access and scale are. They do not go where “someone heard it was secure”.

That is why comparing operating systems only by the number of malware samples or incidents can be misleading. You need context: who uses the system, where it is used, what data it holds and how it is managed.

Practical View: Which System for What?

This table is not a technology religion. It is only a practical view. The operating system should match the task, people, hardware and ability to maintain it. The best system is not the one that wins an argument in the comments. It is the one where the business works, the user can do their job and the administrator is not drinking their third stress coffee before 9:00 AM.

And completely unseriously: for someone who clicks “Congratulations, you won an iPhone”, the best system is one with a good backup, web filtering and someone patient in the family or IT department.

The Most Secure System Is a Well-Managed System

After years of working with different systems, I have come to a simple conclusion: the most secure operating system is not necessarily the one with the best reputation on the internet. The most secure system is the one that is correctly chosen, properly configured, updated, monitored and understood by the people who maintain it.

macOS can be very secure. Windows can be very secure. Linux can be very secure. Red Hat can be an excellent enterprise platform. Fedora can be a great system for technical users. HarmonyOS can be an interesting new ecosystem. But every one of these systems can also be poorly used, badly configured and outdated.

There is no operating system that automatically solves every security problem. And there is no operating system that will protect a user from clicking “Your account has been blocked, click here” if the organisation has no user education, MFA or sensible security controls.

Security is a process. It means updates, backup, encryption, MFA, good passwords, limited privileges, monitoring, user education, application control and sensible management. It also means hardware that is not constantly working at the edge of survival.

Backup also deserves its own sentence. It is one of those things that everyone has “somewhere”, until something actually needs to be restored. Then it often turns out that the backup only worked in a presentation, in Excel or in our imagination. Test your backup before you need it. Not after an incident, not after a failure, not after a call from the boss. Before.

So instead of asking “which operating system is the most secure?”, it is better to ask:

Which operating system best fits my needs, my hardware, and can I secure and maintain it properly?

That question is less exciting than the internet war of “Windows versus Linux versus macOS”, but it is much closer to real IT.

And while we are talking about real IT: check whether your computer or server has RDP exposed to the internet. One day I might tell you how something like that can almost take a company down. But that is a story for another article.

PS. A Quick Security Test for the Brave

• Do you have MFA enabled wherever possible?
• Do you use strong, unique passwords?
• Does your backup actually work?
• Are your operating system and applications updated?
• Do your users know that an “urgent invoice attachment” is not always an invoice?

If you answered “I do not know” to any of these questions — you already know where to start.