Ransom.Win32.NOKO.THDABBC is a ransomware strain targeting Windows systems, classified as low risk due to its limited distribution and infection rates. However, it carries a medium damage potential, encrypting files while avoiding specific extensions. It typically spreads via malicious downloads or as a payload from other malware.
Technical Analysis
Ransom.Win32.NOKO.THDABBC infiltrates systems through malware-dropped files or drive-by downloads. Once executed, it avoids encrypting files with certain extensions, suggesting it may skip system-critical files to maintain host functionality for ransom payment. The ransomware drops a ransom note, though the exact content isn’t detailed in available sources. Persistence mechanisms are not explicitly mentioned, but typical ransomware tactics include registry modifications or scheduled tasks.
Detection names vary by vendor, with Microsoft identifying it as Ransom:Win32/Nokonoko.PB!MTB and Avast as Win32:Nokoyawa-A [Trj]. Recommended actions include deploying endpoint protection with behavioral analysis, monitoring for suspicious file writes, and restricting execution of unsigned binaries in high-risk directories.
Relevance to Security Teams
For Blue Teams and SOC analysts, detection rules should focus on strings related to ransom notes or encryption routines. SIEM alerts should monitor file creation events in user directories with .txt or .html extensions, common ransom note formats. Threat researchers may find static analysis useful due to the lack of advanced obfuscation.
Red Teams may consider this ransomware low-priority for simulation due to its limited impact, but it could be useful for testing decryption workflows. Security teams should prioritize monitoring for related IOCs and updating detection rules to mitigate potential future variants.
Remediation Steps
Infected systems should be isolated to prevent lateral movement. Files should be restored from backups if available. Logs should be analyzed to identify the initial infection vector, such as phishing emails or exploit kits. Proactive measures include updating detection rules and educating users on safe browsing practices.
Conclusion
While Ransom.Win32.NOKO.THDABBC poses minimal widespread risk, its medium damage potential warrants baseline defenses. Security teams should remain vigilant for evolving distribution tactics and update detection rules accordingly. Continued monitoring and proactive measures are essential to mitigate potential threats.
