Sierra Management Group Data Breach Exposes Patient Records

Sierra Management Group Inc., a medical practice management and consulting company based in Newcastle, California, disclosed a data breach involving unauthorized access to its computer systems.

Between December 2025 and March 2026, an unauthorized third party accessed certain Sierra Management Group systems. During that period, the intruder may have accessed and copied files stored on those systems.

On March 7, 2026, Genesis claimed responsibility for the attack in a posting on the dark web. The group stated it had obtained 100 gigabytes of data from the company. According to the posting, the compromised data included personally identifiable information, insurance data, healthcare data, financial data, user folders and data from the company's file server. Genesis said it planned to publish the stolen data within five to six days.

A detailed review of the affected files was completed on or about June 3, 2026. The review determined which files contained personal information, what types of data were involved and which individuals were affected.

At this time, the only information type confirmed in the affected files is names but may include other personal information such as Social Security numbers, addresses, contact details, financial information and more.

The breach was reported to the California Attorney General on June 29, 2026. Consumer notification letters were also sent on June 29, 2026.

Sierra Management Group's response to the breach

Sierra Management Group is offering affected individuals complimentary credit monitoring and identity restoration services through IDX. The length of coverage is either 12 or 24 months, depending on the individual.

To enroll, individuals can visit the IDX enrollment page and enter the enrollment code included in their notification letter. A QR code is also included in the letter for quick access to the enrollment page. The deadline to enroll is Sept. 29, 2026.

Sierra Management Group has set up a dedicated assistance line at 1-833-788-9712. IDX representatives are available Monday through Friday from 6 a.m. to 6 p.m. Pacific Time to answer questions about the incident and help individuals understand the steps they can take.

Individuals may also write to Sierra Management Group at 2001 Rattlesnake Rd., Newcastle, California 95658.