The Yurei ransomware group, first identified in September 2025, operates a typical ransomware model targeting corporate networks with a focus on sectors such as transportation, IT, marketing, and food industries. The ransomware is developed in the Go programming language, which facilitates cross-platform capabilities and ease of deployment. It employs ChaCha20-Poly1305, a modern authenticated encryption algorithm, to encrypt files, ensuring confidentiality and integrity of the encrypted data. Additionally, it uses secp256k1-ECIES (Elliptic Curve Integrated Encryption Scheme) to protect encryption keys, leveraging elliptic curve cryptography for secure key exchange and protection. The ransomware excludes specific directories, file extensions, and files from encryption to avoid disrupting critical system functions, which is a common tactic to maintain system operability and delay detection. The encryption process generates a unique key and nonce per file, making decryption without the attacker’s private key infeasible. The ransom note threatens victims with data leaks and regulatory notifications if the ransom is not paid within five days, indicating a double extortion tactic. Although the ransomware has been observed primarily in Sri Lanka and Nigeria, its use of advanced cryptographic techniques and targeting of corporate networks suggests potential for wider geographic spread. Indicators of compromise include multiple file hashes associated with the ransomware binaries. No known CVEs or exploits in the wild have been reported, and the severity is assessed as medium due to the ransomware’s operational model and encryption strength. The attack techniques include reconnaissance, credential dumping, privilege escalation, and data encryption, aligning with MITRE ATT&CK tactics such as T1082, T1140, T1055, T1112, T1070, T1083, T1566, T1027, T1486, and T1490. The threat actor’s use of Go and modern cryptography indicates a well-resourced and technically capable group.

For European organizations, the Yurei ransomware poses a significant risk to confidentiality, integrity, and availability of corporate data. The use of strong encryption algorithms means that encrypted files are effectively inaccessible without the attacker’s key, potentially causing prolonged operational disruption. The threat of data leaks and regulatory notifications is particularly impactful in Europe due to stringent data protection laws such as GDPR, which mandate timely breach notifications and can result in substantial fines. Industries similar to those targeted so far—transportation, IT, marketing, and food—are critical to European economies and supply chains, increasing the potential for cascading effects. The ransomware’s exclusion of certain files to maintain system functionality may allow it to evade early detection and complicate incident response. Although no known exploits in the wild have been reported yet, the ransomware’s presence and operational model suggest a credible threat that could expand geographically. The medium severity rating reflects the balance between strong encryption and the current limited geographic spread. However, the potential for double extortion increases reputational and financial risks for European entities.

European organizations should implement a multi-layered defense strategy tailored to the Yurei ransomware’s characteristics. First, enforce strict network segmentation to limit lateral movement within corporate networks, especially between critical systems and user workstations. Deploy advanced endpoint detection and response (EDR) solutions capable of identifying behaviors associated with reconnaissance, credential dumping, and privilege escalation (e.g., monitoring for T1082, T1140, T1055 techniques). Regularly audit and restrict administrative privileges to reduce the attack surface. Implement application allowlisting to prevent execution of unauthorized Go-based binaries and monitor for suspicious file hashes matching known Yurei indicators. Backup strategies must include offline and immutable backups to ensure recovery without ransom payment. Conduct phishing awareness training to mitigate initial infection vectors (T1566). Monitor network traffic for unusual encrypted communications or data exfiltration attempts. Finally, prepare incident response plans that include legal and regulatory notification procedures to comply with GDPR and other European data protection laws in case of data leaks.