The breach was confirmed for the Washington Free Beacon by unnamed officials from inside the department, and it apparently happened two weeks ago.
The attackers - thought to be working at the behest of a nation state - have managed to penetrate a 14 computer servers and 20 workstations located at the Department's headquarters, and have succeeded in exfiltrating personally identifiable information on several hundred employees and contractors.
According to reports, there are indications that the attackers might have also had other goals in mind - namely to either steal confidential information or to pave the way for future intrusions that would make that possible.
Taking into consideration the target, the speculation that the attackers were classic cyber spies is not that far fetched. Still, investigators have not indicated that Chinese hackers - the "usual suspects" in cases such as these - are to blame.
The individuals whose personal information has been compromised have been notified by email and advised to encrypt all files and emails containing sensitive information, as well as data stored on hard drives and shared on networks. They were also urged not to store or email private and personal information from the Department's computers, and advised to be on the lookout for social engineering attempts using the stolen personal information.
As things stand now, it seems that no confidential information was stolen during the attack.
"The Departmentís Cybersecurity Team, the Office of Health, Safety and Security and the Inspector Generalís office are working with federal law enforcement to promptly gather detailed information on the nature and scope of the incident and assess the potential impacts to DOE staff and contractors," explained the breach notification.