Cyber Threat Intelligence
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Ransomware Victim Healthcare

Markham Stouffville Hospital

Ransomware attack by Anubis · Disclosed December 16, 2025 · 🇨🇦 Canada

oakvalleyhealth.ca

Date Disclosed
Dec 16, 2025
2025
Threat Group
Anubis
106 total victims
Country
🇨🇦 Canada
Industry
Healthcare

ThreatAI Analysis

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

About the Anubis group

Anubis is a ransomware-as-a-service group active since December 2024 that targets healthcare, engineering, construction, and professional services sectors, offering affiliates a flexible revenue split model and an optional destructive "wipe mode" alongside standard encryption. Anubis has listed 101 victims since February 2025.

Incident Analysis

Markham Stouffville Hospital was targeted by Anubis ransomware, one of the most active ransomware groups in our database with 106 confirmed victims globally. The attack was disclosed on December 16, 2025, when Markham Stouffville Hospital appeared on the group's dark web leak site.

Markham Stouffville Hospital is based in Canada , operating in the Healthcare sector. Canada ranks #2 globally for ransomware attacks, with 890 victims in our 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.

Anubis typically employs a double extortion model: first exfiltrating sensitive data from the victim's systems, then deploying ransomware to encrypt files. Victims face two simultaneous threats — paying to restore access and paying to prevent publication of stolen data. The group's leak site publishes victim names and exfiltrated data as leverage.

Data source: This incident record is sourced from public ransomware group leak site disclosures aggregated via the ransomware.live API. Disclosure date reflects when the victim was published on the leak site, which may differ from the initial date of compromise. This platform does not publish or link to stolen data. Last data update: Aug 16, 2026 22:00 UTC.

Frequently Asked Questions

Was Markham Stouffville Hospital attacked by ransomware?

Yes. Markham Stouffville Hospital was listed as a victim of the Anubis ransomware group on December 16, 2025. The organisation is based in Canada and operates in the Healthcare sector. The disclosure appeared on the group's dark web leak site.

Which ransomware group attacked Markham Stouffville Hospital?

Markham Stouffville Hospital was attacked by Anubis ransomware. Anubis is one of the most active ransomware groups, having claimed 106 victims globally. The group typically employs a double-extortion model: encrypting the victim's files and threatening to publish stolen data.

When did the Markham Stouffville Hospital ransomware attack occur?

The ransomware attack on Markham Stouffville Hospital was disclosed on December 16, 2025. 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 Markham Stouffville Hospital ransomware attack?

The specific data stolen from Markham Stouffville Hospital 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, Markham Stouffville Hospital likely held patient records, medical data, and personally identifiable information (PII).

How can organisations protect against Anubis attacks?

To defend against Anubis 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.