As officials of the Obama administration announced that millions of sensitive records associated with current and past federal employees and contractors had been exposed by a long-running infiltration of the networks and systems of the Office of Personnel Management on June 4, they claimed the breach had been found during a government effort to correct problems with OPM's security. An OPM statement on the attack said that the agency discovered the breach as it had "undertaken an aggressive effort to update its cybersecurity posture." And a DHS spokesperson told Ars that "interagency partners" were helping the OPM improve its network monitoring "through which OPM detected new malicious activity affecting its information technology systems and data in April 2015."

Those statements may not be entirely accurate. According to a Wall Street Journal report, the breach was indeed discovered in April. But according to sources who spoke to the WSJ's Damian Paletta and Siobhan Hughes, it was in fact discovered during a sales demonstration of a network forensics software package called CyFIR by its developer, CyTech Services. "CyTech, trying to show OPM how its cybersecurity product worked, ran a diagnostics study on OPM’s network and discovered malware was embedded on the network," Paletta and Hughes reported.

And, according to federal investigators, that malware may have been in place for over a year. US intelligence agencies have joined the investigation into the breach. But it's still not even clear what data was accessed by the attackers.

Meanwhile, the breach has triggered outrage from unions representing federal employees. In a letter to OPM Director Katherine Archuleta, American Federation of Government Employees president J. David Cox expressed displeasure at the way OPM had handled the breach, calling the 18 months of credit monitoring and $1 million liability insurance OPM is offering federal employees "entirely inadequate, either as compensation or protection from harm."

And he expressed concern about the extent of the breach. "Based on the sketchy information OPM has provided, we believe the Central Personnel Data file was the targeted database, and that the hackers are now in possession of all personnel data for every federal employee, every federal retiree, and up to one million former federal employees," he stated. "We believe that the hackers have every affected person's Social Security number(s), military records and veterans' status information, address, birth date, job and pay history, health insurance, life insurance, and pension information; age, gender, race, union status, and more. Worst, we believe the Social Security numbers were not encrypted, a cybersecurity failure that is absolutely indefensible and outrageous."

Cox demanded that federal employees be allowed to use their government computers "on duty time to attempt to protect themselves from this breach." He said OPM's outsourcing of the responsibility for handling questions about the breach "adds insult to injury," and that federal employees "deserve more than a difficult-to-navigate website and call center contractors who do not know the answers to questions that go beyond a FAQ template."

"AFGE will issue demands to bargain for represented workers, and we ask that you make certain that management is apprised of its responsibility to respond appropriately," he added.