Explore our Ransomware Guide to learn about the threat it poses to your business, the effects of an attack, and what you can do to protect your endpoints.
Synnovis NHS UK Ransomware Attack
Published: 12/2/2025
Written By: Lizzie Danielson
The Synnovis ransomware attack targeted critical IT infrastructure within the NHS system, specifically affecting Synnovis, a diagnostic services provider. This cyberattack led to significant disruption of healthcare services, compromising both patient data and care delivery systems. Its impact reverberated across the NHS and raised questions about cybersecurity readiness in sensitive industries like healthcare.
What is Synnovis Ransomware?
The Synnovis ransomware attack brought healthcare services in parts of the UK to a standstill by encrypting critical systems. Designed to disrupt operations and extract financial compensation, the ransomware also exposed vulnerabilities in healthcare IT systems. Though the specific ransomware strain used remains unclear, its purpose was clear—financial gain at the expense of healthcare delivery.
When did the Synnovis Ransomware attack happen?
The attack was reported in late June 2023, with its effects rippling through the following weeks. This timeline caused prolonged operational disruptions, highlighting the consequences of prolonged ransomware-induced downtime.
Who created Synnovis Ransomware?
The identities of the threat actors behind the Synnovis ransomware attack remain unknown. However, cybersecurity experts suspect a sophisticated cybercriminal group due to the attack’s scale and its targeting of critical healthcare infrastructure.
How did Synnovis Ransomware spread?
The attack primarily exploited known vulnerabilities in outdated IT systems. Reports suggest that the ransomware entered through phishing emails or weak remote desktop protocol (RDP) connections—a common entry point for cyberattacks. Once inside, the ransomware quickly spread across interconnected systems, locking down files and demanding ransom payments for decryption keys.
Victims of the Synnovis Attack
The primary victim of the ransomware attack was Synnovis, along with related NHS services. These disruptions affected diagnostic and laboratory services, indirectly impacting patients relying on timely diagnoses and treatments.
Ransom demands & amount
Exact ransom demands were not disclosed to the public. However, such attacks typically involve demands in cryptocurrency, often in the range of millions of dollars. Officials did not confirm whether any payment was made.
Technical Analysis of Synnovis Ransomware
Synnovis ransomware functioned by encrypting sensitive data files using advanced cryptographic algorithms. It targeted not only databases but also virtual machines and backup systems, making recovery difficult without decryption keys or adequate mitigation measures in place.
Tactics, Techniques & Procedures (TTPs)
The attackers employed tactics such as phishing, lateral movement through compromised networks, and exploitation of software vulnerabilities. Key techniques included using RDP brute force, credential theft, and encryption of critical systems.
Indicators of Compromise (IOCs)
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IP addresses showing unusual activity
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Suspicious domain names linked to malware command and control (C2) servers
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File extensions altered to indicate encryption, such as ".locked"
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Sudden spikes in CPU usage assocciated with encryption processes.
Impact of the Synnovis Ransomware attack
The attack caused immense operational downtime across NHS diagnostic services, resulting in delayed patient care, increased administrative burden, and potential risks to patient outcomes. Financial losses incurred from halted operations and recovery efforts were significant, though specific figures remain undisclosed.
Response & recovery efforts
Recovery efforts involved collaboration between NHS cybersecurity teams, Synnovis staff, and external security experts. Systems were gradually restored over weeks, though the attack exposed critical areas requiring stronger defense mechanisms. The event prompted calls for improved cybersecurity frameworks across the healthcare sector.
Is Synnovis Ransomware still a threat?
While Synnovis ransomware itself appears dormant, the vulnerabilities it exposed remain a concern. Healthcare institutions continue to face elevated cybersecurity threats due to their reliance on interconnected IT systems.
Mitigation & prevention strategies
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Implement multi-factor authentication (MFA) across all systems.
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Conduct regular employee training to identify phishing attempts.
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Keep software and systems updated with the latest security patches.
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Invest in endpoint detection and response (EDR) tools and proactive threat hunting.
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Establish a robust data backup and disaster recovery plan.
Latest News
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Related Educational Articles & Videos
Related Educational Articles & Videos
Learn more about ransomware protection strategies through these Huntress resources:
Read more about Ransomware Explained: A Hub for Guides, Resources, & Solutions
Read more about How Ransomware Attacks Happen
Video
Ransomware is a type of malware that cuts off your access to computers, systems, or networks. Watch the video from our Security Operations Center (SOC) for a breakdown of the ransomware attack path, so you can spot it early, shut it down, and steer clear of hacker paydays.
Read more about Before Ransomware Strikes: Attack Playbook
Ebook
Learn about the key stages of a ransomware attack and effective strategies for protecting yourself.
Synnovis Ransomware FAQs
Synnovis ransomware spreads primarily through phishing emails and unpatched system vulnerabilities. Once inside, it swiftly encrypts files and propagates through the network.
Without the attacker-provided decryption key, decryption is nearly impossible. That's why prevention and regular backups are critical.
Healthcare was the primary target, especially diagnostic services and related NHS operations.
Businesses can defend against attacks by updating software, conducting regular cybersecurity training, using MFA, and implementing a robust backup strategy.
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