Behind the fancy interface and icons, the MacOS operating system which powers Apple computers is significantly different to alternatives like Microsoft Windows. The system has been built from the ground up to increase security and protect users.

This design has been incredibly successful, allowing Apple to create the impression that iMacs and MacBooks are invulnerable, that hackers cannot break into their machines. It is still quite common for people to leave their Mac unprotected by not installing anti-malware software.

But as Mac computers have become more popular, cybercriminals are devoting more time and attention to developing malware to target them. And many people are simply unaware of the risks they face.

Introducing the Shlayer trojan

Most will never have heard of the Shlayer trojan for instance – despite the fact that it has been attacking Mac computers since 2018. Researchers believe that around 10% of all Macs – millions of computers – have been targeted by the malware over the last two years.

The trojan spreads using website pop-ups, usually advising users to download an Adobe Flash Player update to access video content. The malware installer walks the victim through the process of installing the application before downloading additional malicious content itself.

Once installed, Shlayer hijacks the Safari browser to display targeted ads as the user surfs the web. The scammers are paid by advertising networks for every ad – a scam that may be worth millions of pounds every year.

This may not be the most damaging form of malware – but it’s very, very annoying. It also defrauds the companies paying for ads.

A warning for Mac users

Shlayer tells us two things. First, Apple computers can be – and are – infected with malware. There are security weaknesses in the operating system and cybercriminals are exploiting them.

Second, although Shlayer is relatively harmless, other hackers will inevitably use the same techniques for more malicious activities. Expect to see Mac malware becoming more dangerous, stealing passwords and identities and sensitive data.

Time to protect yourself

While Shlayer has been quietly infecting machines since 2018, tools to protect Apple computers have been in existence for much longer. Take Panda Antivirus for Mac for instance, which provides comprehensive defence against malware and all types of computer viruses.

As with any anti-malware toolkit, Panda Antivirus works best when installed before infection. The good news it’s not too late – Panda can still detect and remove Shlayer infections from your computer.

We fully expect to see new examples of Mac malware appearing in the near future – so it’s time to protect yourself now. And if you’re still not sure, take a look at our article Antivirus For Mac: Is It Really Necessary?