Apple has patched a massive security hole that exposed 600,000 Apple Mac users to a trojan virus worldwide.

In the United Kingdom, 68,577 cases of infection have been identified, the third highest figure worldwide.

The malware spread from February 2012, mutated on 16 March and was shutdown by Apple on 3 April.

The Age reports that around a dozen security holes exposed Macs and Microsoft Windows PCs to a malicious software program known as Flashback Trojan.

The Flashback Trojan self-installs after users visit popular mainstream websites such as Dlink that have been infected to distribute the program, according to users sourced by The Verge.

Once the malware infects your machine, it monitors your data traffic from your computer, looking for your usernames and passwords.

The update is available automatically via Software Update on Macs running Mac OS X v10.6.8, Mac OS X Server v10.6.8, OS X Lion v10.7.3 or Lion Server v10.7.3.

A range of malware botnets taking advantage of the security glitch have been identified by Dr Web as:

• godofwar3.rr.nu
• ironmanvideo.rr.nu
• killaoftime.rr.nu
• gangstasparadise.rr.nu
• mystreamvideo.rr.nu
• bestustreamtv.rr.nu
• ustreambesttv.rr.nu
• ustreamtvonline.rr.nu
• ustream-tv.rr.nu
• ustream.rr.nu

The Age IT professional and journalists Brian Krebs advises one simple quick fix to this and future Java security flaws - delete it. "If you don't need Java, remove it from your system, whether you are a Mac or Windows user," he writes.

To do so, disable individual plug-ins by clicking the disable link under its listing on your computer. In Mozilla Firefox for Mac, click Tools, Add-ons, and disable the Java plugin(s).

Apple's website says it does not comment on security issues until a full investigation has occurred and a reliable fix created.