Phrack Magazine’s latest issue #72 has unveiled a significant data leak from a suspected North Korean hacking operation, including exploit tactics, compromised system details, and a sophisticated Linux rootkit.
The dump, linked to a Chinese threat actor targeting South Korean and Taiwanese government and private sectors, shows overlaps with the North Korean Kimsuky APT group.
It reveals access to internal networks and sensitive certificates, alongside screenshots of active backdoor development.
The full archive, containing live malware for multiple platforms, demands careful handling due to its hazardous contents. This exposure highlights advanced persistent threats employing stealthy tools for espionage and lateral movement.
Rootkit Capabilities
The rootkit, analyzed from its 2025 variant, operates as a Loadable Kernel Module (LKM) built on the khook library, enabling kernel system call interception to evade detection.
It conceals itself from lsmod listings, hides processes, network activity, and persistence files in /etc/init.d and /etc/rc*.d directories.
Activation occurs via a magic packet on any port, triggering an encrypted backdoor for shell execution, file transfers, proxy setup, or host chaining.
Commands incorporate anti-forensic measures, such as redirecting shell histories to /dev/null and preventing timeouts, while all traffic remains encrypted.
According to the report, the module resides in /usr/lib64/tracker-fs, tainting the kernel as unsigned (named vmwfxs by default), and communicates via a /proc/acpi/pcicard socket.
Its fragility ties it to specific kernel versions, potentially failing on updates, yet it blends into legitimate services like web or SSH ports, bypassing firewalls.
Incident Response
Detection relies on tools like Sandfly for automated alerts on hidden files, tainted kernels, and cloaked processes, revealing anomalies without updates.
Manual checks include scanning for unsigned module taints via dmesg or /var/log/kern.log, direct file stats on suspected paths despite invisibility in listings, and inspecting systemd services like tracker-fs.service.
The backdoor binary at /usr/include/tracker-fs/tracker-efs shows malicious strings, while hidden processes evade ps and ss but can be decloaked with specialized utilities.
Features like multi-hop chaining, SOCKS5 proxies, and delayed packet streams enhance evasion. For cleanup, isolation and rebuild are advised over remediation, as root access obscures full compromise extent.
Security teams should prioritize generic hunting over fragile indicators, avoiding hash-based searches due to mutability.
This rootkit underscores nation-state toolkit sophistication, urging vigilant monitoring of Linux environments amid rising threats.
Indicators of Compromise (IOCs)
| Category | Indicator | Notes |
|---|---|---|
| Kernel Module | vmwfxs (default name) | Unsigned, causes kernel taint; changeable |
| File Path | /usr/lib64/tracker-fs | Hidden malicious module; direct stat reveals |
| Backdoor Binary | /usr/include/tracker-fs/tracker-efs | Concealed; strings show anti-forensics |
| Persistence Files | /etc/init.d/tracker-fs, /etc/rc*.d/S90tracker-fs | Boot scripts for module insertion; hidden |
| Socket | /proc/acpi/pcicard | Communication endpoint; ls -al detects |
| Systemd Service | tracker-fs.service | Reveals via systemctl status; drift indicator |
| Environment Vars | HISTFILE=/dev/null, TMOUT=0 | Anti-forensic shell settings in hidden processes |
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