Health Plan of San Mateo Breach - January 17, 2023

The Health Plan of San Mateo is a non-profit health insurance program that serves all San Mateo residents eligible for Medi-Cal or Medicare services. More than 150,000 members are served by the program within the county, and a small number of those users may have been exposed in a recent data breach caused by an email attack.

What Was the Breach?

• Birth Dates
• Full Names
• Member Identification Numbers
• Nurse Advice Line Call Details

How Did the Breach Occur?

The San Mateo Health Plan breach occurred because an attacker broke into a single employee email account in an effort to alter the employee's direct deposit information. There is no proof that the attacker accessed the documents contained within the account, but a spreadsheet containing information gathered by the nurse advice line could have been viewed while the user was on the account.

When Did This Breach Occur?

The Health Plan San Mateo data breach occurred on January 17, 2023. On that day, the email account was compromised, and it took several days before the issue was resolved. While inside the account, the attacker may have accessed some personal information for a small number of patients relying on the Health Plan of San Mateo nurse advice services.

Who Does the Breach Impact?

A small portion of the Health Plan of San Mateo patients that relied on the nurse advice services may have had some basic information exposed due to this attack. If you recently used the nurse advice services, you should take steps to protect your personal accounts and watch for future phishing attacks in your email. Be careful to avoid providing any personal information via email, and avoid any suspicious links in your email.

How Many Files Does the Breach Affect?

The Health Plan of San Mateo breach only exposed a small number of documents contained within a single email account. The documents may have exposed hundreds of different individuals, though.