US health insurer Anthem hacked Reuters

US health insurance major Anthem has become the victim of a hacking attack, potentially affecting personal data of 80 million customers and employees.

The hacking attack discovered last week was reported by The Wall Street Journal for the first time. Anthem estimates that "tens of millions" of records were stolen in the attack, the newspaper reported.

"Despite our efforts, Anthem was the target of a very sophisticated external cyber attack. These attackers gained unauthorized access to Anthem's IT system and have obtained personal information from our current and former members such as their names, birthdays, medical IDs/social security numbers, street addresses, email addresses and employment information, including income data," CEO Joseph Swedish said in a message on the official website.

"Based on what we know now, there is no evidence that credit card or medical information, such as claims, test results or diagnostic codes were targeted or compromised."

He noted that the company immediately acted to close the security vulnerability, once it came to know about the attack. The company also contacted the FBI and has been fully cooperating with the investigation.

Anthem has retained cybersecurity firm Mandiant to evaluate its systems and identify solutions. The company is offering free credit monitoring and identity protection services to affected customers.

"I want to personally apologise to each of you for what has happened, as I know you expect us to protect your information. We will continue to do everything in our power to make our systems and security processes better and more secure, and hope that we can earn back your trust and confidence in Anthem," Swedish added.

Cyber security has recently become a major concern for large companies, governments and individuals in line with the rising number of hacking attacks and the leakage of large amounts of data.

Hackers now appear more interested in stealing medical records rather than electronic data as the former proves to be more profitable and less risky, according to security experts.

Kelly Yee, Vice President at Penango, the secure webmail and encryption company in the US, earlier told IB Times UK hackers are now more interested in medical data rather than credit and debit card data.