Facebook did not pinpoint the origin of the hacker but it provided some details as to how it unfolded; The security lapse was traced to a handful of employees who visited a mobile software developer's website that had been compromised, which led to malware being installed on the workers' laptops. The PCs were infected even though they were supposed to be protected by the latest anti-virus software and were equipped with other up-to-date protection.

Facebook linked part of the problem to a security hole in the Java software that triggered a safety alert from the U.S. Department of Homeland Security last month. The government agency advised computer users to disable Java on their machines because of a weakness that could be exploited by hackers.

Oracle Corp., the owner of Java, has since issued a security patch that it says has fixed the problem. In its post, Facebook said it received the Java fix two weeks ago.

Whether the fault is in Facebook is in the Java application, this incident should serve as a warning sign for the social networking giant as the next time the unnamed assailants may not be so kind as to leave everything untouched.

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