The first known ransomware attack on Apple Inc's Mac computers, which was discovered over the weekend, was downloaded more than 6,000 times before the threat was contained, according to a developer whose product was tainted with the malicious software.

Hackers infected Macs with the "KeRanger" ransomware through a tainted copy of Transmission, a popular program for transferring data through the BitTorrent peer-to-peer file sharing network. So-called ransomware is a type of malicious software that restricts access to a computer system in some way and demands the user pay a ransom to the malware operators to remove the restriction.