The US HealthCare.gov insurance enrollment website's security was breached by hackers in July 2014, according to federal officials.
HealthCare.gov stores personal details of Americans, including Social Security numbers, financial data and names of family members.
During the breach, the hacker was able to upload malicious software but could not view or take consumers’ personal data, according to the evidence of investigators, reported The Wall Street Journal.
The officials said that hacker only gained access to a server used to test code for HealthCare.gov.
According to the Department of Health and Human Services (HHS) official, the attack is the first successful intrusion into the website, where millions of Americans bought insurance last year under the 2010 Affordable Care Act.
HHS in a written statement was quoted by the news publication as saying: "Our review indicates that the server did not contain consumer personal information; data was not transmitted outside the agency, and the website was not specifically targeted."
The site was launched in October 2013 and around 5.4 million applicants signed up for health plans through the site by the end of open enrollment.
The Department of Homeland Security, Federal Bureau of Investigation and National Security Agency have also started investigation on the issue.
Image: Hacker broke into US insurance enrollment website. Photo: courtesy of hyena reality/ FreeDigitalPhotos.net.