Security firm MalwareBytes discovered the first strain called "FruitFly" earlier this year.
A second version, though, called "FruitFly 2" has also appeared.
FruitFly operates quietly in the background. It spies on users through the computer's camera and captures images of what's displayed on the screen and logs key strokes.
Researchers do not know who is behind it or how it got on computers.
They also don't know if it targeted individuals randomly or directly.
According to Forbes, malware outbreaks like this are rare with Mac computers.
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