A full four million current and former US federal employees apparently had their personal information hacked, in what US official estimate may be the largest breach of the government's computer networks in history.
The Office of Personnel Management announced the hack on Thursday, noting that nearly every federal government agency was targeted by the hackers and warning those who may have had their sensitive data breached to watch their bank statements and get new credit reports.
It is possible that millions of additional government employees may have been hacked as well given that the assessment of the damage is still ongoing, reports CNN.
Reportedly workers in the legislative and judicial branches, as well as uniformed military personnel, were not harmed by the breach.
Signs of the cyberattack were first discovered as the federal personnel office tightened its cybersecurity system, and the information breach was fully discovered in April. In May, it was learned that highly sensitive data had been accessed.
As for who is behind the massive hack, US investigators say they think the handiwork of the Chinese government can be traced, with officials revealing Chinese military hackers are gathering a database of Americans for some unknown and apparently nefarious purpose.
However, the Chinese Embassy in Washington denied the accusations, with spokesman Zhu Haiquan saying, "cyberattacks conducted across countries are hard to track and therefore the source of attacks is difficult to identify. Jumping to conclusions and making hypothetical accusation is not responsible and counterproductive."
"Cyberattack is a global threat which could only be addressed by international cooperation based on mutual trust and mutual respect," said Haiquan.
Weighing in on the hack was Senator Ron Johnson (R-WI), chairman of the Senate Homeland Security and Governmental Affairs Committee.
"It is disturbing to learn that hackers could have sensitive personal information on a huge number of current and former federal employees – and, if media reports are correct, that information could be in the hands of China," said Johnson.
He noted that the Office of Personnel Management "says it 'has undertaken an aggressive effort to update its cybersecurity posture.' Plainly, it must do a better job, especially given the sensitive nature of the information it holds."
Representative Adam Schiff (D-CA), who is the leading Democrat in the House Intelligence Committee, said cyberattacks are one of the "greatest challenges we face on a daily basis."
"It's clear that a substantial improvement in our cyber databases and defenses is perilously overdue," said Schiff. "That's why the House moved forward on cybersecurity legislation earlier this year, and it's my hope that this latest incident will spur the Senate to action."