There have been several articles recently about a type of malware on the Mac that apparently has been around for some time. Here is one article describing the malware, titled by some as FruitFly. Another article I read said that Apple has released an update to prevent future infections.
Malwarebytes anti-malware for the Mac (here) will detect and presumably remove the malware. A 'techy' article for the nerdy can be read here. Although there have been no reports of damage done by this malware, you could scan your Mac with Malwarebytes to see if you've been infected.