In April, federal authorities detected an ongoing remote attack targeting the United States' Office of Personnel Management (OPM) computer systems. This situation may have gone on for months, possibly even longer, but the White House only made the discovery public last Friday. While the attack was eventually uncovered using the Department of Homeland Security's (DHS) Einstein—the multibillion-dollar intrusion detection and prevention system that stands guard over much of the federal government's Internet traffic—it managed to evade this detection entirely until another OPM breach spurred deeper examination.
While anonymous administration officials have blamed China for the attack (and many in the security community believe that the attack bears the hallmark of Chinese state-sponsored espionage), no direct evidence has been offered. The FBI blamed a previous breach at an OPM contractor the Chinese, and security firm iSight Partners told The Washington Post that this latest attack was linked to the same group that breached health insurer Anthem.
OPM is the human resources department for the civilian agencies of the federal government, so this attack exposed records for over four million current and former government employees at places like the Department of Defense. The breach, which CNN dubbed "the biggest government hack ever," included background and security clearance investigations on employees' families, neighbors, and close associates stored in the Electronic Questionnaires for Investigations Processing (e-QIP) system and other databases. The attack also affected a data center operated by Department of the Interior used by OPM and other agencies as a shared service—the result of data center consolidation ordered by the Obama administration. As a result, even more agencies may have been directly affected.