While Apple only currently supports the last two versions of its operating system - 10.7 and 10.6 - the company has issued two security updates for Mac OS X 10.5 Leopard, showing just how much of an issue the Flashback malware is.
The first is the Flashback Removal Security Update, which Apple describes as follows:
This update runs a malware removal tool that will remove the most common variants of the Flashback malware. If the Flashback malware is found, it presents a dialog notifying the user that malware was removed. There is no indication to the user if malware is not found.
The second is Leopard Security Update 2012-003, which performs an action that was in the latest update for the Safari web browser:
This update disables Adobe Flash Player if it is older than 10.1.102.64 by moving its files to a new directory. This update presents the option to install an updated version of Flash Player from the Adobe website.
Leopard users should run these updates to protect themselves from the issues presented by the Flashback malware, and by old versions of Flash Player. These updates are available via Software Update, or from Apple's Downloads page.