A new and sophisticated ransomware strain, NotLockBit, has emerged, targeting both Windows and macOS systems with tailored attack strategies. Written in Go, NotLockBit uses a combination of AES and RSA encryption protocols to lock files on the infected systems. The ransomware focuses on high-value file types, including personal documents, professional files, multimedia, and virtual machine data. Encrypted files are renamed with a unique identifier and an .abcd extension, leaving the original files deleted, making recovery without the decryption key nearly impossible. NotLockBit’s cross-platform functionality and advanced capabilities set it apart as a significant threat in the ransomware landscape.
In addition to encryption, NotLockBit carries out data exfiltration, transferring stolen files to attacker-controlled cloud storage, primarily Amazon S3 buckets. This enables the attackers to leverage double extortion tactics, threatening not only data encryption but also the public release or sale of sensitive information. This data theft adds another layer of pressure on victims, increasing the likelihood of ransom payments. For macOS users, the ransomware uses the osascript command to change the desktop background to display a ransom note, marking the completion of the attack.
One of the key features of NotLockBit is its self-deletion mechanism. After completing the attack, it removes its binary from the infected system and deletes shadow copies, significantly hindering recovery efforts. It also employs obfuscation techniques to avoid detection, with some variants fully stripped of function names, making reverse-engineering challenging for security researchers. The ransomware also performs detailed reconnaissance, especially in macOS environments, gathering critical system information such as hardware specifications, operating system version, and network configurations.
Security experts have emphasized the growing sophistication of ransomware families like NotLockBit, which demonstrates an alarming evolution in cyberattack methods. To mitigate the impact of such threats, organizations are urged to implement robust security measures, including regular offline backups, advanced endpoint protection, strict network security protocols, and comprehensive employee training to recognize phishing attempts and other social engineering tactics. As ransomware attacks become more complex and targeted, proactive monitoring and security awareness will be crucial in defending against these evolving threats.
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