Apple has released a Java patch that comes with a detection and removal capability for the most common strains of the prolific Flashback trojan.
The update, for Mac OS X 10.7 (Lion) and 10.6 (Snow Leopard), will kill the malware, which is capable of stealing data and hijacking search traffic, among other malicious actions.
At its peak, Flashback contaminated some 650,000 machines worldwide, according to experts.
The fix from Apple also disables the automatic execution of Java applets, which are most commonly used by the average user to play games and view certain images on websites.
Individuals who want Java to automatically run can adjust their settings by visiting the software's "Preferences" application.
Lion users must make use of Java within 35 days, or it will automatically switch off again.
Security experts supported the inclusion of that capability, believing it to be important considering many computer users run unneeded and out-of-date third-party software, which is then commonly used to exploit their machines.
Mikko Hypponen, chief research officer of anti-malware provider F-Secure, tweeted on Friday: "I like the idea of Safari disabling the Java plug-in if unused for 35 days. Next, we need to do the same on all browsers. For all plug-ins."
Ian Melven, a senior security engineer at Mozilla, responded in a tweet that he and his team are working on similar features for the Firefox browser.
Meanwhile, on Friday, security firm Symantec said it has discovered a trojan that is taking advantage of the same (now-patched) vulnerability in Java that Flashback used to spread.
Known as "Sabpab," the "very low" risk trojan, when installed on a machine, opens a back door that can enable a remote attacker to create new processes, download files, take screenshots or install additional malware.