It was originally reported that the personal data of 4 million current, former and potential federal employees was stolen from the Office of Personnel Management (OPM) web site. Now that total is believed to be closer to 18 million records.
The Chinese government is believed to be the source of the attack, although they have disputed this statement.
The OPM office learned of the data breach after it launched an effort to tighten its cyber security defense system. When it found malicious activity authorities used a system called EINSTEIN to unearth the information breach in April, the Department of Homeland Security said.
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