Security vendor Sophos is warning Mac users that a new version of the MacSweeper Trojan has emerged which it is dubbing the Troj/MacSwp-B.
The malware, also known as the Imunizator Trojan, works in a similar way to MacSweeper attempting to convince users that their Mac has privacy issues and that they should download software to 'solve' the issue.
"Windows users are no stranger to scareware like this, but it is rarer on the Mac. Nevertheless, the discovery of this Trojan horse does follow fast on the heels of other malware that has been identified on Mac OS X in recent months," said Graham Cluley, senior technology consultant for Sophos.
"Cybercrime against Mac users may be small in comparison to Windows attacks, but it is growing.
"Mac users need to learn from the mistakes made by their Windows cousins in the past and ensure that they have defenses in place, are up-to-date with patches and exercise caution about what they run on their computer."