Was Memorial Sloan Kettering Cancer Center hit by ransomware?

Memorial Sloan Kettering Cancer Center was listed by the Meow ransomware operation (United States), and stolen data was published on the group's leak site. Darkfield tracks this disclosure with the original leak post, screenshot and group context.

Who is the Meow ransomware group?

Meow is a ransomware operator tracked by Darkfield. See the full operator dossier for its known victims, sectors targeted, IOCs and leak-site infrastructure.

What data was leaked in the Memorial Sloan Kettering Cancer Center breach?

Meow published data attributed to Memorial Sloan Kettering Cancer Center. Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

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Memorial Sloan Kettering Cancer Center

Claimed by Meow · listed 3 years ago

31m

Age

since listed · data leaked

Status timeline

ListedDec 12, 2023
Data leakeddate unknown

At a glance

Group: Meow
Status: Data leaked
Country: United States
Sector: Healthcare
Listed on leak site: Dec 12, 2023

About the victim

AI dossier — public-source company profile

Memorial Sloan Kettering Cancer Center (MSK) is a world-leading cancer treatment and research institution founded in 1884 and headquartered in New York City. It operates Memorial Hospital for patient care and the Sloan Kettering Institute for basic and translational cancer research, running over 100 laboratories across 9 research programs. MSK is widely regarded as one of the foremost cancer centers globally, treating adults and children while training the next generation of oncology clinicians and scientists.

Industry: Oncology / Cancer Research & Treatment
Address: 1275 York Avenue, New York, NY 10065
Employees: 10000+
Founded: 1884

Attack summary

Severity: critical — Memorial Sloan Kettering is a major oncology center handling highly sensitive patient medical records, clinical trial data, and PII at very large scale. Data_published status indicates regulated health data (HIPAA-protected PHI) has already been released, qualifying as critical severity.

The Meow ransomware group has listed Memorial Sloan Kettering Cancer Center as a victim with a disclosed status of data_published, claiming data has been exfiltrated and published. The leak post preview does not specify data volume or file types, but the disclosure status indicates data has been released publicly.

critical

Data the group says was taken

AI dossier — extracted from the leak post

Patient records (probable)
Medical/clinical data (probable)
Research data (probable)
Staff/employee information (probable)

What the group claims

PREVIEW

Sources

Source

Indexed 3 years ago

This page surfaces a public ransomware disclosure indexed by Darkfield. Original posts come from the operator's own leak site; we cross-check against ransomware.live, RansomLook and RansomWatch where applicable. Share this URL freely.

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Disclosure context

About Meow

Meow is a relatively new ransomware group that emerged in November 2023, primarily motivated by financial gain through extortion activities targeting organizations across multiple sectors. The group has compromised at least 145 known victims in a short operational timeframe, demonstrating rapid scaling of their criminal enterprise. Based on their targeting patterns, Meow appears to focus heavily on English-speaking countries, with the United States, United Kingdom, and Canada representing their primary victim base, though they have also expanded operations to include targets in Italy and Colombia. The group shows a preference for attacking business services organizations, manufacturing companies, healthcare institutions, and agriculture and food production entities, suggesting they may employ broad-spectrum targeting rather than highly specialized sector focus. Their emergence in late 2023 and the significant victim count achieved in a relatively short period indicates either a sophisticated operation with experienced operators or potential links to existing ransomware ecosystems, though specific details about their attack methodology, initial access vectors, encryption techniques, or data exfiltration practices have not been extensively documented by major threat intelligence sources. Given the recent timeline of their emergence and limited public reporting from established security researchers, detailed technical analysis of their tools, tactics, and procedures remains sparse. The group appears to remain active as of current reporting, though comprehensive law enforcement actions or major disruption efforts have not been publicly documented. The group has been linked to 145 public disclosures across our corpus. First observed on a leak site on November 24, 2023; most recent post November 19, 2024. The operation is currently inactive.

Timeline of this disclosure

December 12, 2023Memorial Sloan Kettering Cancer Center listed by Meowon the group's public leak site

Other recent disclosures by Meow

Meow has been linked to 145 public victims on Darkfield. A sample of the most recent:

See the full Meow dossier →

Sector and geography

This disclosure adds to ransomware activity in the Healthcare sector, which has 2,600 disclosures indexed across all operators we track. Geographically, Memorial Sloan Kettering Cancer Center is reported in United States, a country with 11,033 ransomware disclosures in our corpus.

If your organisation is affected

A listing by Meow means Memorial Sloan Kettering Cancer Center appeared on a ransomware extortion site and data attributed to it has been published. If this is your organisation, or a supplier you depend on, the priority is to confirm the intrusion and contain it before the window to act closes.

Engage your incident-response team and preserve forensic evidence before remediating — do not wipe affected systems first.
Force a password reset and revoke active sessions for exposed accounts; rotate any credentials, API keys or certificates that may have been in the stolen data.
Assess regulatory notification duties (GDPR, NIS2, sector regulators) — many carry a 72-hour reporting clock from awareness.
Report the incident to your national CERT, CISA (United States), as required for your jurisdiction.
Monitor for the data appearing on Meow's leak site and across paste and breach channels, and brief downstream partners who may be exposed through you.

How we know this. Darkfield monitors public ransomware leak sites continuously, archiving every new disclosure and the data later released against the victim. Each entry on this page is sourced from the operator's own publication and cross-checked against complementary OSINT feeds (RansomLook, ransomware.live, RansomWatch). We do not collect or host stolen data — only the metadata, timestamps and screenshots needed to make the public disclosure searchable and accountable. Records here are corrected when the original post is edited, retracted, or merged with another disclosure.