Apple announced the breach this morning, noting that malware had targeted a "limited number" of Mac systems. Reuters notes that the same hacker group is suspected of an attack on Facebook machines last week.

In a statement the company made to The Loop, Apple said that the malware infected the systems through a vulnerability in the Java browser plug-in. "The malware was employed in an attack against Apple and other companies, and was spread through a website for software developers. We identified a small number of systems within Apple that were infected and isolated them from our network. There is no evidence that any data left Apple. We are working closely with law enforcement to find the source of the malware."