MacOS malware threats and defences against them

Apple's classic "Get a Mac" advertising campaign, which ran from 2006 to 2009, featured two characters: a casual man personifying a Mac and a formal, suit-clad man representing a PC. The series highlighted perceived differences in their features and reliability. For example, in one ad, the PC is sick with viruses. He sneezes, tells the Mac to keep his distance, and warns that he could get infected too. Mac simply hands him a tissue and reassures him that Macs don't get viruses. But does that claim still hold true?

For businesses relying on macOS, 2024 served as a critical warning. Malware campaigns targeting corporate users increased significantly throughout the year. To achieve their goals, threat actors used a diverse range of tactics, from infostealers disguised as productivity apps to sophisticated backdoors designed to steal data.

In this article, we’ll review the most common macOS malware threats and the effective defenses every business should know.

Why macOS is a growing target for cybercriminals

The long-held belief that macOS is ‘safe by default’ is a dangerous misconception As businesses increasingly adopt macOS, cybercriminals are dedicating more resources to targeting these systems.

Businesses using Macs now face tangible risks previously associated mainly with Windows environments, particularly from ransomware. While once considered a rarity on macOS, the threat has evolved significantly since the appearance of KeRanger in 2016, the first functioning ransomware for macOS. As threat actors accelerate their targeting of the Apple ecosystem, the Objective-See Foundation reported a 50% increase in new malware families in 2023 compared to the previous year.

Modern macOS ransomware attacks often employ double-extortion tactics. This means attackers don't just encrypt critical files to halt operations. They first exfiltrate sensitive corporate data and then threaten to publish it if their financial demands aren't met. For businesses, this creates a multi-faceted crisis: facing operational paralysis from locked systems, direct financial loss from the ransom, and severe reputational damage from a public data breach. Alongside this potent ransomware threat, a sophisticated macOS infostealer creates another powerful vector for devastating data breaches.

Common types of macOS malware

Understanding the types of threats is the first step in defending against them. Here are some common malware types that corporate Apple users encounter:

Adware

While often seen as a minor nuisance, adware on corporate macOS devices can be a serious issue. It bombards Mac users with unwanted pop-ups and redirects, slowing down systems and consuming network bandwidth. More critically, adware can lead to phishing attempts by displaying fake security alerts or enticing users to download more malicious software. For example, the Bundlore family of adware often gets bundled with legitimate software downloads, making its way onto corporate devices undetected.

Trojans

Trojans are insidious because they disguise themselves as legitimate or useful applications. Think productivity tools, system optimizers, or even fake software system updates. Once installed, they can create backdoors, steal data, or download further malware. A notable example is Shlayer, a Trojan often found disguised as Adobe Flash Player updates, which has historically been a widespread threat to macOS users.

Ransomware

Ransomware encrypts files and demands payment for their release. For a business, a ransomware attack on macOS endpoints can bring operations to a halt, leading to significant financial losses and reputational damage. While less common than on Windows, macOS ransomware, such as KeRanger mentioned earlier, has proven its capability to infiltrate and lock down systems.

Infostealer malware

As the name suggests, infostealer malware aims to steal sensitive data such as login credentials, banking details, browser history, and personal files. This directly translates to compromised accounts, intellectual property theft, and potential compliance violations. Atomic macOS Stealer (AMOS) is a recent example that actively targets various browser data, cryptocurrency wallets, and system information.

Viruses and worms

Though less prevalent in macOS than other malware types, traditional viruses and worms still pose a threat. Viruses attach themselves to legitimate programs and require user action to spread, while worms can self-replicate and spread across networks without human intervention. Their impact can be significant, especially in poorly segmented corporate networks.

Advanced attack techniques targeting macOS

Cybercriminals constantly advance their methods to bypass macOS security and stay hidden on your network. A strong defense, therefore, requires a clear understanding of these advanced methods.

For example, in a supply chain attack, attackers don't target you directly. Instead, they go after your trusted software providers. They inject malicious code into legitimate apps or updates before they even reach your business. As a result, when you deploy what you believe is a safe application, you install malware. This method is effective because it bypasses security by exploiting your trust in the third-party software you use.

Another advanced method is a zero-day attack that exploits a hidden flaw in your software. Imagine a secret backdoor that no one—not even your IT team—knows about yet. This is a zero-day vulnerability, as developers have had "zero days" to fix it. If attackers find that backdoor first, they can sneak through it, giving them a huge advantage to steal information or take control of systems long before a patch is available.

Getting onto a system is only half the battle for malware; it also needs to stay there. This is known as persistence, and it’s how malware survives a simple restart. On macOS, attackers often create malicious LaunchAgents and LaunchDaemons to automatically run their programs, or use cron jobs to relaunch them on a schedule. For the ultimate level of control, they can target Kernel Extensions (KEXTs), which lets them load their malware into the very heart of the operating system.

How macOS malware gets into your company

While attackers use highly advanced techniques to target your company’s macOS, malware's initial entry point is often surprisingly simple. It's usually not a complex hack that gets them in the door, but a clever trick that exploits everyday human habits.

The oldest trick in the book is still one of the most effective: phishing emails. An employee might get a message that looks like a legitimate invoice, a shipping notification from a partner, or an urgent request from IT. All it takes is one click on a malicious link or attachment for the malware to get a foothold.

This principle of deception extends to physical methods as well. Believe it or not, an old-school infected USB drive from a conference can still introduce malware to your corporate network. A more modern twist is the misuse of AirDrop, where an employee with open sharing settings might be tricked into accepting a malicious file in a public space.

Lastly, malicious apps and browser extensions downloaded outside the official Mac App Store are a considerable source of macOS malware. An employee might find what looks like a handy PDF converter or a "free" version of expensive software on a third-party website. The app might even work as advertised, but it could be a Trojan horse, running malware silently in the background and stealing corporate data.

Best practices to protect macOS endpoints in business

Now that we've covered the threats, it's important to note that protecting your company's Macs isn't about finding a single solution. Effective security comes from building a multi-layered and strategic defence.

The first layer is a solid foundation of security policies for every Apple device in your company. This means enforcing the essentials: requiring strong passwords, ensuring FileVault disk encryption is always turned on, and pushing out regular OS and application security updates to patch vulnerabilities. The easiest way to manage this across your company is with a Mobile Device Management (MDM) solution, which lets your IT team automate these critical settings.

While strong policies are the ground rules, they must be backed by dedicated security software. Think of Apple's built-in features like XProtect as a good lock on the door, but you also need a complete alarm system. Dedicated macOS security solutions provide this extra layer, offering advanced capabilities like real-time threat detection, vulnerability scanning, and centralized management for all your company’s Mac devices. For instance, use a dedicated threat exposure management platform that continuously scans the dark web in real time to detect cyber threats targeting your organization, like infostealer malware logs, leaked databases, and collection of stolen credentials combinations.

Finally, the most advanced technology can't replace your strongest security asset: a well-informed employee. You can have the best tools in the world, but it won't stop someone from clicking on a convincing phishing link. Regular training is key. Teach your team how to spot the red flags of a phishing email, remind them of the dangers of downloading unvetted software, and create a culture where it's okay to ask, "Hey, does this look suspicious to you?" When your team knows what to look for, they become an active part of your defense.

Key takeaways for securing macOS in business

Apple's "safe by default" era is over. With their growing presence in the business scene, Macs are a prime target requiring the same vigilance as any other computer. This vigilance is necessary because threats are multifaceted. They often use a simple entry point like a phishing email to deliver sophisticated malware like ransomware or infostealers.

That’s why an effective defense cannot rely on Apple's built-in features alone. A truly robust security posture is multi-layered, combining strong technical policies, a dedicated threat exposure management solution, and continuous user training to create a resilient defense against modern threats.