While I would never personally recommend a Kaspersky product to save my life, you know, because they're believed to spy on people for the Kremlin (which you can read about here: The Kremlin and Putin are using Kaspersky Labs to spy on you!), there's a new report from them that might have some merit:
According to the report I got from Threatpost, Kaspersky says 1 in 10 Macs is infected with the Shlayer Trojan.
What is the Shlayer Trojan?
It's a trojan downloader. It spreads via malware that poses as other applications. It most likely impersonates Adobe Flash. It's goal is to fetch and install adware variants. After it's installed the affected user is blasted with ads and pop-ups. It also hijacks browser searches and modifies the search results to promote more ads.
Shlayer leverages popular services that allow for sharing links (like YouTube or Wikipedia, to name a few).
Posing as an Adobe Flash update is a common means of delivery.
How can you protect yourself from Shlayer?
Be more careful what you click, and be more careful when it comes to installing new software. For example, if you're prompted with a message telling you your Flash Player is out of date it's probably wise to disregard it or close the notification outright.
Adobe Flash is an archaic and needless piece of software in the world of HTML 5. Adobe itself is planning to completely discontinue use of the platform by the end of this year.
Otherwise you might want to consider a next generation Anti-Virus program like Blackberry|Cylance.
Need more info?
Check out the link to Threatpost I included above or visit the Kaspersky site directly here (if you're okay with being spied on by Russian Spooks).