Even as Apple is yet to release a system update that will protect Mac from the notorious malware, Mac Defender, hackers are growing in the Mac community and now an upgraded version of the malware, called Mac Guard, has arrived.

Mac Defender, the first major malware that threatened Mac users, is a fake anti-virus program that appeared several weeks ago. It pretended to be a security program for Mac that gives false alarms to Mac users, giving a sense of panic that they need to install the “security program” Mac Defender. Upon installing the software and entering the credit card information, their information will leak to the hands of the hackers.

The numbers of Mac that have been affected by Mac Defender increased, and ZDNet estimated around 60,000 to 120,000 Mac users might have been infected.

Even though it was being clear that Apple is under threat, Apple has been quite about it until recently. In an interview with Ed Bott of ZDNet, an AppleCare representative said they were told not to remove the malware from customer’s computer, as “We can’t set the expectation to the customers that we will be able to remove all malware in the future.”

It was not until late Tuesday that Apple gave an announcement that a system update is on its way. Apple has also given an instruction on how to avoid installing the malware and how to remove it if infected (click here).

However, Apple has not released the system update. It seems Apple has been unable to act quickly enough and it is doubtful whether Apple can keep pace with the malwares that are surfacing on Macs.

Intego discovered today a variant of Mac Defender that goes by the name of Mac Guard. Unlike Mac Defender, which requires an administrative password to install, Mac Guard is capable of installing itself without the users having to type their administrative password. In other words, Mac users are more vulnerable against Mac Guard than they are against Mac Defender.

Although the method of Mac Guard is not tricky compared to other malwares for PC, the appearance of such malware for Mac could cause a Mac users to panic, considering that many of them are not ready to fight against such malicious attacks.

It has been rumored that Mac OS X is more secure than Windows. However critics say the lack of Mac virus in the past is due to insignificant number of users rather than the security of its platform. Now that the number of Mac users are increasing, it is not not totally unexpected for Mac-specific malwares to surface.

How will Apple react now? Has the vulnerability of the Mac been exposed? It may be too early to tell but one thing is clear - Mac Defender and Mac Guard have busted the myth that Macs are virus-proof.