Apple releases a support note admitting that Mac Defender is indeed a problem, providing instructions on how to clean it. Then a new version of the malware appears almost immediately, one that automatically runs its installer. Macs are still unlikely to see the first or fully-automated versions of the second type of malware. As our numbers grow, it’s only natural we will see more of the third type of online crime as well as the fourth type of cyber-crime. Windows 7 is actually more secure than OS X, but the gap narrows every year.”]
Source: https://www.csoonline.com/article/2128571/mac-defender–pay-attention-but-don-t-panic.html