Online attackers successfully penetrated the Department of Energy (DOE) network in the middle of January and obtained copies of personally identifiable information (PII) pertaining to several hundred of the agency's employees and contractors, said InformationWeek.

The agency first detailed the "cybersecurity incident," which affected the network at the agency's headquarters, in a memo circulated to all employees Friday, it said. "We believe several hundred DOE employees' and contractors' PII may have been affected. As individual affected employees are identified, they will be notified and offered assistance on steps they can take to protect themselves from potential identity theft," according to the memo.

The DOE has launched a full-scale investigation into the breach, involving its Joint Cybersecurity Coordination Center, or JC3, which helps the agency track and report on all attacks launched against the agency, said InformationWeek, as well as the DOE's Office of Health, Safety and Security and Inspector General's office, together with one or more federal law enforcement agencies.