Facebook officials did not identify the specific kind of malware that the attackers installed on the compromised laptops, but said that the employee's machines were infected when they visited a mobile developer Web site that was hosting the Java exploit. When the employees visited the site, the exploit attacked a zero-day vulnerability in Java that was able to bypass the software's sandbox and enable the attackers to install malware. The company said it reported the vulnerability to Oracle, which then patched the Java bug on Feb. 1."
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