Apple computer owners are being subjected to a number of specialised malware attacks that insists Mac users download a malware version of the popular MacDefender antivirus application, infecting their computers as a result. The infection appears to be targeting people searching Google Images.
To reassure users of the official MacDefender software, it's creator has taken to the official website to warn users of the malware campaign:
IMPORTANT NOTE: As it seems someone wrote a virus/malware application named mac defender (MacDefender.app) for OS X. If you see an application named like this DO NOT DOWNLOAD/INSTALL it. I would never release an application named like this.
Luckily, disabling and removing the bogus MacDefender application is easy. If you have been infected and want to make sure it no longer resides on your system, follow the steps below:
Above information condensed from: http://thenextweb.com/apple/2011/05/02/bogus-macdefender-malware-campaign-targets-mac-users-using-google-images/