Skip to content
Cyber Threat
CTI Academy Sponsor CTI Academy
Ransomware victim Healthcare

O2 Dental Group

Listed by Interlock on · organisation based in United States

o2smiles.com

Disclosed
Oct 5, 2026
Leak-site listing date
Threat group
Interlock
138 victims listed
Country
United States
#1 most targeted
Sector
Healthcare

ThreatAI analysis

Compiled from this incident record and the threat intelligence profile for Interlock. Figures and technique mappings are quoted from the source data, not inferred.

Interlock listed O2 Dental Group on its dark web leak site on 5 October 2026, a ransomware group targeting healthcare critical infrastructure, already having claimed over two million patient records from one victim.

About the Interlock group

Interlock is a ransomware group first observed in September 2024 that targets critical infrastructure sectors including healthcare, government, education, and technology across North America and Europe using double-extortion, with 57+ claimed victims including a major US dialysis provider exposing over two million patient records. Interlock has listed 132 victims since December 2023.

Vulnerabilities Interlock is recorded exploiting

1 of these 1 are in the CISA Known Exploited Vulnerabilities catalog, 1 of them recorded by CISA as used in ransomware campaigns. CVEs attributed to Interlock across its reported activity. There is no indication that any of these was involved in the O2 Dental Group incident — the source data does not record an entry point.

Incident analysis

O2 Dental Group was listed by Interlock ransomware, a group with 138 victims recorded in this database. The listing appeared on the group's leak site on October 5, 2026.

O2 Dental Group is based in United States and operates in the Healthcare sector. United States ranks #1 worldwide for ransomware disclosures, with 9,988 victims in this database.

Sector context. Healthcare organisations are high-value ransomware targets because patient data is extremely sensitive, regulatory penalties for breaches are severe, and operational downtime can threaten patient safety — all factors that increase ransom payment pressure.

Interlock typically follows a double extortion model: data is exfiltrated from the victim's systems before files are encrypted, so the victim faces two demands at once — pay to restore access, and pay to keep stolen data unpublished. The leak site, where this listing appeared, is the lever for the second demand.

Source. Public leak-site disclosures aggregated via the ransomware.live API. The disclosure date is when the listing was published, which can differ from the date of compromise. This site does not publish or link to stolen data. Last updated .

Frequently asked questions

Was O2 Dental Group attacked by ransomware?

Yes. O2 Dental Group was listed as a victim of the Interlock ransomware group on October 5, 2026. The organisation is based in United States and operates in the Healthcare sector. The disclosure appeared on the group's dark web leak site.

Which ransomware group attacked O2 Dental Group?

O2 Dental Group was attacked by Interlock ransomware. Interlock is one of the most active ransomware groups, having claimed 138 victims globally. The group typically employs a double-extortion model: encrypting the victim's files and threatening to publish stolen data.

When did the O2 Dental Group ransomware attack occur?

The ransomware attack on O2 Dental Group was disclosed on October 5, 2026. This date reflects when the victim was published on the threat group's leak site, which may differ from the actual date of initial compromise.

What data was stolen in the O2 Dental Group ransomware attack?

The specific data stolen from O2 Dental Group has not been independently verified by this platform. Ransomware groups typically exfiltrate data before encrypting systems and use the threat of publication to pressure victims. As a Healthcare organisation, O2 Dental Group likely held patient records, medical data, and personally identifiable information (PII).

How can organisations protect against Interlock attacks?

To defend against Interlock and similar threat actors, organisations should: maintain regular offline backups tested for restoration; implement network segmentation to limit lateral movement; deploy multi-factor authentication on all remote access; use endpoint detection and response (EDR) tools; conduct regular phishing and security awareness training; and monitor threat intelligence feeds for indicators of compromise (IOCs) associated with active groups.