Skip to content
Vol. 1 · Ed. 2026
CyberGlossary
Entry № 1036

Rhysida Ransomware

Was ist Rhysida Ransomware?

Rhysida RansomwareA ransomware-as-a-service group first observed in May 2023, known for targeting healthcare, education, and government victims and for high-profile attacks including the British Library and Insomniac Games breaches.


Rhysida is a ransomware-as-a-service group that emerged in May 2023 and quickly became one of the more active newcomers in the 2023–2025 cybercrime landscape, joining a wave of post-LockBit/post-ALPHV operators. The encryptor is written in C++ and uses AES-256 plus ChaCha20 hybrid encryption with file extensions changed to `.rhysida`, leaving the ransom note `CriticalBreachDetected.pdf`. Rhysida favors double-extortion: it exfiltrates data to its 'Rhysida' Tor leak site before encryption and lists victims publicly to pressure payment. The actor has hit a notably broad mix of sectors — local government, K-12 schools, hospitals (Prospect Medical, several U.K. NHS supply chains), the British Library (October 2023, a months-long outage), and Insomniac Games (Sony, December 2023). Initial access has included VPN credentials harvested by info-stealers, phishing, and exploitation of known vulnerabilities; affiliates often use Cobalt Strike, AnyDesk/Atera, and Mimikatz post-exploitation. CISA, the FBI, MS-ISAC, and U.K. NCSC published joint advisories on Rhysida TTPs in late 2023.

Beispiele

  1. 01

    Rhysida claimed responsibility for the October 2023 British Library attack, which disrupted catalog, payment, and IT systems for many months.

  2. 02

    An MSSP detects Rhysida pre-encryption by alerting on Atera / AnyDesk installations on unmanaged servers, a recurring tradecraft pattern.

Häufige Fragen

Was ist Rhysida Ransomware?

A ransomware-as-a-service group first observed in May 2023, known for targeting healthcare, education, and government victims and for high-profile attacks including the British Library and Insomniac Games breaches. Es gehört zur Kategorie Schadsoftware der Cybersicherheit.

Was bedeutet Rhysida Ransomware?

A ransomware-as-a-service group first observed in May 2023, known for targeting healthcare, education, and government victims and for high-profile attacks including the British Library and Insomniac Games breaches.

Wie funktioniert Rhysida Ransomware?

Rhysida is a ransomware-as-a-service group that emerged in May 2023 and quickly became one of the more active newcomers in the 2023–2025 cybercrime landscape, joining a wave of post-LockBit/post-ALPHV operators. The encryptor is written in C++ and uses AES-256 plus ChaCha20 hybrid encryption with file extensions changed to `.rhysida`, leaving the ransom note `CriticalBreachDetected.pdf`. Rhysida favors double-extortion: it exfiltrates data to its 'Rhysida' Tor leak site before encryption and lists victims publicly to pressure payment. The actor has hit a notably broad mix of sectors — local government, K-12 schools, hospitals (Prospect Medical, several U.K. NHS supply chains), the British Library (October 2023, a months-long outage), and Insomniac Games (Sony, December 2023). Initial access has included VPN credentials harvested by info-stealers, phishing, and exploitation of known vulnerabilities; affiliates often use Cobalt Strike, AnyDesk/Atera, and Mimikatz post-exploitation. CISA, the FBI, MS-ISAC, and U.K. NCSC published joint advisories on Rhysida TTPs in late 2023.

Wie schützt man sich gegen Rhysida Ransomware?

Schutzmaßnahmen gegen Rhysida Ransomware kombinieren typischerweise technische Kontrollen und operative Praktiken, wie in der Definition oben beschrieben.

Welche anderen Bezeichnungen gibt es für Rhysida Ransomware?

Übliche alternative Bezeichnungen: Rhysida.

Verwandte Begriffe