BlackTech has been linked to a newly discovered Linux backdoor deployment targeting organizations in Japan, highlighting how an old tool can be repurposed for cyberespionage. Investigators should act quickly and consider file-system carving or memory forensics when expected malware files are absent, particularly following suspicious SSH activity or Linux SSH credential theft. Verifying the Common Name field (Source – IIJ Security Diary) Organizations should prioritize any unexpected SSH movement between servers as a high-risk signal, ensuring endpoint logs, authentication records, and proxy configurations remain accessible for at least an appropriate timeframe.
Key IoCs: Type Indicator Description SHA-256 944b774d592f5e7fe2c34ac6c3abb2a77bfa96707c4f3c33ac77b8d54800244f BlueShell variant dropper SHA-256 3228da011423853efd3d94ce3a28046b5ca19e921861ea5aee2700bc90fc1d55 BlueShell variant File name apid Name associated with the BlueShell variant dropper File name tmpkthread Name associated with the BlueShell variant C2 server 48.216.210.91:443 Reported command-and-control server address and port Proxy server 10.210.20.254:3128 Proxy server specified in observed configuration Process disguise kworker1212 Process name used to mimic a Linux kernel worker File path tmp.ICECache Path used in previous BlueShell deployment campaign Process disguise /usr/sbin/cron -f Process name used previously in BlueShell deployment campaign Securely integrate into authorized cybersecurity platforms like MISP, VirusTotal, or your Security Information and Event Management (SIEM) system.
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