**Overview:** Ryuk is a prominent ransomware operation that emerged in October 2018, primarily motivated by financial gain through high-value targeted attacks against enterprise networks. The group became one of the most destructive ransomware families, focusing on large organizations capable of paying substantial ransoms rather than conducting widespread automated campaigns.
**Origin & Affiliation:** Ryuk is believed to have origins tied to Russian-speaking cybercriminals and has been linked to the North Korean state-sponsored group Lazarus, though it operates primarily as an independent financially-motivated enterprise. The group has been associated with the TrickBot botnet infrastructure and has collaborated with various initial access brokers rather than operating as a traditional RaaS model.
**Attack Methodology:** Ryuk typically gains initial access through spear-phishing campaigns, exploitation of Remote Desktop Protocol vulnerabilities, or by purchasing access from other cybercriminal groups operating banking trojans like TrickBot and Emotet. The operators conduct extensive network reconnaissance using tools like Cobalt Strike, PowerShell Empire, and AdFind before deploying ransomware, often disabling security software and deleting backups. While primarily focused on encryption for ransom, later campaigns incorporated data exfiltration threats as part of double extortion tactics.
**Notable Campaigns:** Ryuk has been responsible for major attacks against numerous high-profile targets including multiple hospitals and healthcare systems, causing significant operational disruptions, and has targeted critical infrastructure sectors including municipal governments and educational institutions. The group has demanded ransoms ranging from hundreds of thousands to millions of dollars, with some of the highest recorded payouts in ransomware history.
**Current Status:** Ryuk operations significantly declined following law enforcement disruptions of associated infrastructure like TrickBot in late 2020 and 2021, with many security researchers considering the original Ryuk group largely inactive, though some variants and successors have emerged under different names. The group has been linked to 48 public disclosures across our corpus. First observed on a leak site on October 4, 2018; most recent post May 18, 2021. The operation is currently inactive.
Sector and geography
This disclosure adds to ransomware activity in the Healthcare and Public Health sector, which has 52 disclosures indexed across all operators we track. Geographically, Sonoma Valley Hospital is reported in United States, a country with 7,392 ransomware disclosures in our corpus.
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.
