Apple promised to release a security update to address Mac Defender malware and its variants, and that update arrived Tuesday afternoon. Security Update 2011-003 is now available for all Macs running Snow Leopard, and brings file quarantine updates, as well as a malware removal tool.
The OSX.MacDefender.A definition has been added to the OS X File Quarantine database, which means if a user downloads the malware, it will automatically pop up a dialog warning the user that the file will damage your computer, and provide an option to delete the file. The update also allows Apple to automatically update the known malware definitions list through daily updates. Users can opt out of this feature in Security Preferences, shown below.
The security update also automatically searches for and removes Mac Defender and its known variants upon install. If it detects the malware in your system, it will notify you once the update is installed.
It’s great to see Apple getting out ahead of this malware threat before it really gets out of hand, but as always, the first step to protecting your computer starts with you. Don’t ever install something when you’re not sure that it comes from trustworthy origins, and remember that if a website is telling you you’re infected without you having asked to begin with, it’s a safe bet that it’s not a genuine report.