NightSpire is a ransomware threat actor group that has been active since February 2025, employing aggressive tactics and a specialized infrastructure resembling a Ransomware-as-a-Service (RaaS) model. The group operates a Dedicated Leak Site where they publicly post victim information and countdown timers threatening to release stolen data, leveraging a double-extortion strategy. This means they not only encrypt victims' files but also exfiltrate sensitive data to pressure victims into paying the ransom. NightSpire targets multiple industries across various countries, with initial cases reported in South Korea and at least one known affected country in Europe (Poland). Technically, NightSpire ransomware encrypts files using either block or full encryption methods. For specific file extensions, encryption is performed in 1MB blocks to optimize efficiency. Encrypted files are appended with the ".nspire" extension, and a ransom note is placed in each affected folder to inform victims of the attack and payment instructions. The ransomware uses a hybrid cryptographic approach: an AES symmetric key is used to encrypt file contents, and this AES key is itself encrypted with an RSA public key appended at the end of each infected file. This design ensures strong encryption that is difficult to break without the private RSA key held by the attackers. The group employs multiple tactics and techniques consistent with advanced ransomware operations, including credential dumping, process injection, disabling security tools, and obfuscation, as indicated by the referenced MITRE ATT&CK techniques (e.g., T1489 - Service Stop, T1566 - Phishing, T1055 - Process Injection). They also maintain various communication channels for ransom negotiations and use threatening language to coerce victims. Currently, there are no known public exploits or CVEs associated with NightSpire ransomware, and no patches are available. The threat is ongoing and evolving, with a medium severity rating assigned based on current impact and capabilities.

For European organizations, NightSpire ransomware poses a significant risk due to its double-extortion tactics, which threaten both data confidentiality and availability. The encryption of critical files can disrupt business operations, leading to downtime, loss of productivity, and financial losses. The exfiltration and public exposure of sensitive data can cause reputational damage, regulatory penalties (especially under GDPR), and loss of customer trust. Industries with high-value data or critical infrastructure are particularly vulnerable, as attackers may prioritize targets that can yield higher ransom payments. The presence of at least one affected European country (Poland) indicates potential for spread within Europe, especially given the group's multi-country targeting approach. The ransomware's use of strong cryptographic methods and block encryption techniques complicates recovery efforts, often necessitating ransom payment or reliance on backups. The threat also increases the burden on incident response teams and cybersecurity resources, requiring enhanced monitoring and rapid containment capabilities.

1. Implement robust, offline, and regularly tested backups to ensure data recovery without paying ransom. 2. Employ network segmentation and strict access controls to limit lateral movement within corporate networks. 3. Deploy advanced endpoint detection and response (EDR) solutions capable of detecting process injection, credential dumping, and suspicious service stoppages. 4. Enforce multi-factor authentication (MFA) across all remote access and privileged accounts to reduce risk of credential compromise. 5. Conduct regular phishing awareness training to reduce the likelihood of initial infection via social engineering. 6. Monitor for indicators of compromise (IOCs) such as the provided file hashes and unusual file extensions (.nspire). 7. Harden systems by disabling unnecessary services and applying the principle of least privilege. 8. Establish incident response plans specifically addressing ransomware scenarios, including communication strategies for leak site threats. 9. Collaborate with national cybersecurity centers and share threat intelligence to stay updated on NightSpire activity. 10. Use network traffic analysis to detect communication with known NightSpire infrastructure or negotiation channels.