Last week, the US Office of Personnel Management (OPM) announced that a massive cybersecurity breach in April 2015 possibly compromised the personal data of up to 4 million current and former US federal employees.
A government source told ABC News that the hack can potentially be used to “map relationships across the entire federal government” by constructing a database of “who works with who.”
Employees from the Central Intelligence Agency and National Security Agency have not been impacted, although if they worked in another part of the government where their information is managed by OPM, their data may have also been compromised, the source explained.
Employees at the Department of Defense are “believed” to have been spared because their information is managed by a classified, internal.mil computer network instead of the.gov address managed by OPM, according to the media report.
Currently, authorities are trying to determine what data was stolen in the hack, but are considering “all exposed information as potentially stolen,” the government source said.
OPM serves as the US government’s human resource department. The agency's responsibilities include the management federal pension benefits and conducting background investigations for security clearances.
Following the announcement of the hack US media cited an anonymous US official saying Chinese hackers were behind the attack. China has denied the allegations.
The White House has not made public who they believe is behind the attack.