Are you one of the 4 million? Here's what to watch for

Feds, watch your inboxes.

Starting June 8, the Office of Personnel Management will be sending emails to the roughly 4 million current and former federal workers whose personally identifiable information (PII) was potentially exposed in the massive data breach made public late on June 4.

The email address from which notifications will come: opmcio@csid.com.

CSID is a Texas-based security, identify protection and fraud detection firm. Emails, containing information about the credit monitoring and identity theft protection services Uncle Sam will be providing affected feds, will be sent between June 8 and June 19, and letters will be mailed to affected personnel for which OPM does not have an email address. OPM said in a statement that the credit monitoring services also will be provided by CSID, and more information will be available on CSID's website starting June 8 at 9 a.m. EDT.

In its June 4 statements on the breach, OPM stressed that federal personnel should be wary of unsolicited phone calls, emails and other contact, and urged government employees to start monitoring their credit reports.

Sen. Susan Collins (R- Maine), told the Associated Press that the hackers responsible for the breach are believed to be based in China, and that it appears they may have been targeting individuals who hold security clearances. The breach took place in December, but was not discovered until April after OPM initiated new cybersecurity measures. The Department of Homeland Security said its Einstein intrusion-detection-and-prevention system discovered the hack of OPM's systems and the Interior Department's data center, though it's unclear why the detection occurred only after a tremendous number of records had been copied by hackers.

"OPM seems a tad blasé about this breach stating that 'OPM, using new tools, discovered the breach in April,'" said Richard Blech, CEO of security and ID-management firm Secure Channels. "The new tools cannot be very good if it takes four months to find out you have been breached."

Blech noted that the data likely made its way through the black market very quickly, and he said the personnel files should have been "deeply encrypted" to keep them safe in the event of a breach.

Mark Bower, global director of product management at HP Security Voltage, said the PII will facilitate "one of the most effective secondary attacks" – spear-phishing – on government systems.

"Beyond spear-phishing, knowing detailed personal information past and present creates possible cross-agency attacks given job history data which appears to be in the mix," Bower noted. "Thus, it's likely this attack is less about money, but more about gaining deeper access to other systems and agencies."