A mysterious piece of malware has been infecting hundreds of Mac computers for yearsand no one noticed until a few months ago. Earlier this year, an ex-NSA hacker started looking into a piece of malware he described to me as "unique" and "intriguing." It was a slightly different strain of a malware discovered on four computers earlier this year by security firm Malwarebytes, known as "FruitFly."This first strain had researchers scratching their heads.