Rafael Salema Marques, a Brazilian researcher, published a PoC about the existence of Mabouia ransomware, the first ransomware that targets Mac OS X. Ransomware encrypts files that are virtually impossible to decrypt with the computing means available to ordinary users. The only way to decrypt the files is paying to the malware creator to retrieve the password that unlocks the files Which is exactly what you would do if I had not held up important files, you would have to pay $500.”]
Source: http://securityaffairs.co/wordpress/41755/cyber-crime/mabouia-ransomware-mac-os-x.html