Facebook said on Friday it was the target of a series of attacks from an unidentified hacker group, but no user data were compromised.
"Last month, Facebook security discovered that our systems had been targeted in a sophisticated attack," the company said in a blog post. "The attack occurred when a handful of employees visited a mobile developer website that was compromised."
(Read More: Americans Willing to Spend More to Thwart Cyber Attacks: Survey )
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The company said as soon as it discovered the presence of malware, it "remediated all infected machines, informed law enforcement, and began a significant investigation that continues to this day."
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