St. Louis-based Express Scripts disclosed last week it received an anonymous letter that included the names, Social Security numbers, birth dates and, in some cases, prescription information of 75 members. The writer or writers threatened to release millions more of similar records if the business failed to pay an unspecified sum of money.
Meanwhile, the company also revealed on Tuesday that a number of its clients have received letters threatening to expose the same confidential data.
Express Scripts has roughly 50 million members and several thousand clients, which includes employers, government programs, managed-care organizations and unions, said Steve Littlejohn, a company spokesman.
The company has yet to determine the cause of the breach but has isolated from where in its databases the information was lifted, he said.
"What we know is that these criminals that have been sending these letters have included information in the letters that would indicate a breach," Littlejohn said.
Bill Bartow, vice president of product management at data security solutions provider Tizor Systems, said the incident smells like an inside job.
"Someone got to their database," he told SCMagazineUS.com on Wednesday. "Typically when you get to that level, it's an insider or someone with stolen or compromised credentials."
Bartow said safeguarding the database is often ignored by businesses, and he stressed the need for stronger authentication and monitoring solutions.
Littlejohn said Express Scripts is not responding to the demand and continues a round-the-clock investigation. In addition, the company is offering members free identity-theft services if they become victims.
"You can't tolerate crimes like this in our data-rich business environment," he said.
Anyone with information should contact the FBI at (800) CALL-FBI (225-5324). A spokesman for the agency's St. Louis field office could not be reached for comment on Wednesday.