The Interlock ransomware group has conducted a cyberattack against the City of St. Paul, resulting in the leakage of approximately 43GB of data. Ransomware attacks typically involve the deployment of malicious software that encrypts victim data, rendering it inaccessible until a ransom is paid. In this incident, the attackers not only encrypted data but also exfiltrated a significant volume of sensitive information, which they subsequently leaked publicly. This tactic is often used to pressure victims into paying ransoms by threatening reputational damage and regulatory scrutiny. Although specific technical details such as the ransomware variant, infection vector, or exploited vulnerabilities are not provided, the attack's scale and data leakage indicate a sophisticated operation. The absence of known exploits in the wild and lack of patch information suggest that the attack may have leveraged social engineering, phishing, or unpatched system weaknesses. The leak of 43GB of data implies substantial exposure of potentially sensitive municipal information, which could include personally identifiable information (PII), internal communications, or operational data. The attack was reported on Reddit's InfoSecNews subreddit and linked to an external news source, indicating limited public discussion but credible newsworthiness due to the nature of the incident and the involved ransomware group.

For European organizations, the Interlock ransomware group's activities highlight the persistent threat of ransomware attacks that combine data encryption with data exfiltration and public leaks. While this specific attack targeted a U.S. city, European municipalities and public sector entities face similar risks due to comparable IT infrastructures and the value of their data. The leakage of large volumes of sensitive data can lead to severe privacy breaches, regulatory penalties under GDPR, loss of public trust, and operational disruptions. Additionally, the public leak of data can facilitate secondary attacks such as identity theft, fraud, or further cyber intrusions. The attack underscores the importance of robust incident response and data protection measures. European organizations must consider the risk of ransomware groups adopting double extortion tactics, where data theft complements encryption to maximize pressure on victims. The reputational damage and potential legal consequences are significant, especially for public sector bodies responsible for citizen data and critical services.

European organizations should implement multi-layered defenses tailored to counter ransomware threats like Interlock. Specific recommendations include: 1) Conduct thorough network segmentation to limit lateral movement in case of compromise. 2) Enforce strict access controls and least privilege principles, especially for administrative accounts. 3) Deploy advanced endpoint detection and response (EDR) tools capable of identifying ransomware behaviors and data exfiltration attempts. 4) Regularly back up critical data with offline or immutable backups to ensure recovery without paying ransom. 5) Implement comprehensive phishing awareness training to reduce the risk of social engineering-based intrusions. 6) Monitor network traffic for unusual data transfers that could indicate exfiltration. 7) Apply timely patching of known vulnerabilities and maintain an up-to-date inventory of assets. 8) Develop and regularly test incident response plans that include procedures for ransomware and data breach scenarios. 9) Utilize threat intelligence feeds to stay informed about emerging ransomware groups and tactics. 10) Consider deploying data loss prevention (DLP) solutions to detect and block unauthorized data transfers.