Snow Leopard Security Update 2011-03 Mac Defender Malware Threat, Apple Announced

Apple has released a security update for users of Mac OS X Snow Leopard. "The installation process for this update will search for and remove known variants of the MacDefender malware. If a known variant was detected and removed, the user will be notified via an alert after the update is installed," explained Apple.The update […]

Apple has released a security update for users of Mac OS X Snow Leopard. "The installation process for this update will search for and remove known variants of the MacDefender malware. If a known variant was detected and removed, the user will be notified via an alert after the update is installed," explained Apple.

The update also enables the Mac OS X 10.6.7 to update its internal list of known malware on a daily basis via a new background process:

The OSX.MacDefender.A definition has been added to the malware check within File Quarantine. The system will check daily for updates to the File Quarantine malware definition list. An opt-out capability is provided via the "Automatically update safe downloads list" checkbox in Security Preferences.

File Quarantine
Available for: Mac OS X v10.6.7, Mac OS X Server v10.6.7
Impact: Definition added
Description: The OSX.MacDefender.A definition has been added to the malware check within File Quarantine.

File Quarantine
Available for: Mac OS X v10.6.7, Mac OS X Server v10.6.7
Impact: Automatically update the known malware definitions
Description: The system will check daily for updates to the File Quarantine malware definition list. An opt-out capability is provided via the "Automatically update safe downloads list" checkbox in Security Preferences.

Malware removal
Available for: Mac OS X v10.6.7, Mac OS X Server v10.6.7
Impact: Remove the MacDefender malware if detected
Description: The installation process for this update will search for and remove known variants of the MacDefender malware. If a known variant was detected and removed, the user will be notified via an alert after the update is installed.

Apple explains that the 2.36MB download "provides additional protection by checking for the MacDefender malware and its known variants". If Apple finds the pesky MacDefender malware on your system, the computer "will quit this malware, delete any persistent files, and correct any modifications made to configuration or login files".

You can also download the standalone Mac OS X Snow Leopard Security Update 2011-03 here. Apple has also published a support document KBHT4651 regarding XProtect.