Security Experts:

3.7 Million Exposed in Banner Health Breach

Banner Health is warning 3.7 million patients, staff and food and beverage customers that their personal data may have been stolen during a security breach traced back to June 23. Headquartered in Arizona, Banner is one of the largest non-profit healthcare systems in the US. It owns and operates 29 acute-care hospitals and numerous health-related services. An announcement issued Wednesday said that it will be mailing advisory letters to all those who may be affected.

The breach was discovered on July 7. Attackers had gained access to the systems that process payment card data in some of their food and beverage outlets. It is possible that anyone who bought anything in certain of these outlets by payment card between June 23 and July 7 could be affected. Payment for medical services are not affected.

However, further investigations led to the discovery on July 13 that attackers had also gained access to further systems holding patient and health plan information that "may have included names, birthdates, addresses, physicians' names, dates of service, claims information, and possibly health insurance information and social security numbers." This phase of the investigation also revealed that the attack was initiated on June 17. This is currently all that is publicly known about the breach. 

Banner stated that it "immediately launched an investigation, hired a leading forensics firm, took steps to block the cyber attackers and contacted law enforcement." It doesn't specify the forensics firm, although The Arizona Republic suggests it is Mandiant. If Mandiant was hired immediately (that is, on or very soon after 7 July), then it is possible that it was Mandiant that discovered the PHI breach, and traced the intrusion to June 23.

It seems likely, given the timing, that this was a single breach rather than two separate attacks. This implies that either the payment system and the records system were held on the same physical or logical network (which should not have been the case), or that the attacker managed to bridge two separate network segments. This could have been done if he had or acquired sufficiently privileged credentials.

In recent years cyber criminals have sought PHI over and above card data. PHI is a rich source of personal data that can be used in identity theft. While it is relatively easy to change a payment card, it is less easy to change an identity. For this reason the black market resale value of PHI is far higher than card data. In March 2016, Mick Coady from PricewaterhouseCoopers told CNBC a single medical record tied to an individual can now sell for "up to $1,100... About two years ago, it was probably worth no more than $50."

In the Banner breach it would seem that the attackers managed to steal both card data and PHI data together.

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Kevin Townsend is a Senior Contributor at SecurityWeek. He has been writing about high tech issues since before the birth of Microsoft. For the last 15 years he has specialized in information security; and has had many thousands of articles published in dozens of different magazines – from The Times and the Financial Times to current and long-gone computer magazines.