The attack was caused by “a sophisticated cybercrime group” as part of a cybercrime campaign against the insurance industry, according to the release.

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.