A group of cybercriminals hacked into data systems at insurance company Aflac, possibly gaining access to sensitive information such as Social Security numbers and health reports, the company said on Friday.

Aflac, a U.S. insurance provider that covers millions of policyholders, warned some of its customers' most sensitive data may have been stolen in a recent cyberattack. Why it matters: Aflac warned that a "sophisticated cybercrime group" was behind the intrusion and said many insurance providers are currently battling the same group.