Apple’s own marketing helped build this myth for years, and it has always been false. macOS gets less malware than Windows because it has a smaller, more locked-down share of desktops — not because it is immune. Two documented cases show exactly how real, and how quiet, Mac infections can be.
KeRanger: the first working ransomware for Mac
On 4 March 2016, researchers at Palo Alto Networks found KeRanger, malicious code hidden inside an official installer of Transmission, a popular BitTorrent client, after attackers compromised the app’s own download server.
The installer carried a legitimate Apple developer signature, which let it walk straight past Gatekeeper, the checkpoint macOS uses to decide whether an app is safe to open. Once running, it waited three days, then encrypted the victim’s files and demanded one bitcoin — about $400 at the time — to unlock them. Over 7,000 Mac users installed the infected app before it was caught.
Silver Sparrow: malware built for a chip Apple had just released
In February 2021, Red Canary’s detection team found a new malware cluster they named Silver Sparrow. Malwarebytes counted it on 29,139 Mac endpoints across 153 countries — the United States, the United Kingdom, Canada, France and Germany most of all.
What made it notable: one version included a binary compiled to run natively on Apple’s brand-new M1 chip, at a time when almost no malware targeted Apple Silicon at all. Researchers watched it for over a week and never saw it deliver a final payload — it simply sat there, checking in, capable of installing anything its operators chose next.
What this means for you
- Macs run real malware, including ransomware and threats built for the newest Apple chips — this is not a hypothetical.
- The two cases above got in through a trusted, signed installer and a compromised download — not an obviously sketchy website.
- A dormant threat like Silver Sparrow does nothing suspicious to a signature scanner while it waits; only its network behaviour — checking in on a schedule — gives it away.
How FireAI and HisnLabs fit in
The point isn’t that Macs are unsafe — it’s that "it’s a Mac, it can’t get infected" is exactly the assumption that lets something like Silver Sparrow or KeRanger sit unnoticed; a firewall that shows you every outbound connection is what catches what a signature-based scanner missed.
FireAI is HisnLabs’ own product: an on-device AI firewall for Mac. It shows every connection your apps make, in plain language, and lets you decide what leaves your Mac — its AI runs locally, so your traffic is never sent to us or anyone else. HisnLabs’ security research team is the group that keeps that decision-making accurate: cataloguing which domains are ordinary telemetry versus a real product, tracking the country and network behind a connection, and training the on-device model (its Autopilot feature) on real traffic patterns, all without any of it leaving your Mac.
You can read the technical decisions behind it, or try FireAI for 17 days, at FireAI, by HisnLabs.