There is a malware (malicious software) threat that can affect all Mac OS X systems.  Users running with Administrator level accounts with Safari set to open safe files automatically are particularly at risk.  This program pretends to be an AntiVirus program for Mac OS, but isn’t really.  If you see this on your screen, close it immediately:

MacDefender Malware Screenshot

Those responsible for spreading the malware are exploiting users’ interest in late breaking news about Bin Laden’s death, however, other avenues are possible.

For more information see the following bulletins:

http://www.macrumors.com/2011/05/02/new-macdefender-malware-threat-for-mac-os-x/

http://isc.sans.edu/diary.html?storyid=10813

Tags: MacOS, Malware.