Threat Actors Target Linux SSH Servers to Deploy SVF Botnet

AhnLab Security Intelligence Center (ASEC) has been actively tracking cyber threats exploiting vulnerable Linux servers through strategically deployed honeypots, with SSH services using weak credentials emerging as a prime target for distributed denial-of-service (DDoS) and cryptocurrency mining actors.

In a recent incident, ASEC observed threat actors successfully infiltrating a honeypot Linux server via brute-force attacks on SSH, subsequently deploying the SVF Botnet malware.

This Python-based DDoS bot, attributed to the “SVF Team,” leverages Discord as its command-and-control (C&C) infrastructure and incorporates proxy servers to enhance attack evasion.

The installation process involves creating a virtual environment, installing dependencies like discord.py, requests, aiohttp, and lxml, followed by downloading the main.py script from a termbin URL and executing it with a server group parameter, such as “-s 5,” to facilitate grouped command execution.

Botnet Functionality

Upon, the SVF Botnet authenticates with a Discord bot token upon execution, enabling remote control while reporting the infected server’s designated group via webhook for targeted DDoS orchestration.

Its command set predominantly supports Layer 7 (L7) HTTP flood and Layer 4 (L4) UDP flood attacks, with variants including customizable parameters for threads, packet strength, and concurrency.

Unique to SVF is its proxy integration: it scrapes public proxy lists from multiple GitHub repositories and websites, validates them by attempting Google logins, and randomly selects proxies during HTTP floods to obfuscate origins and bypass defenses.

Commands like $load populate the proxy pool, while $customhttp and $customudp enable tailored assaults.

Additional directives handle bot restarts, crashes, and attack halts, reflecting a modular design despite its simplicity.

Post-update, the bot fetches improved versions from a specific IP, suggesting potential evolution into more sophisticated strains.

Security Implications

This exploitation underscores the risks to inadequately secured Linux environments, transforming them into unwitting DDoS nodes under threat actor control.

Administrators must enforce robust, frequently rotated passwords to thwart brute-force and dictionary attacks, apply the latest patches against vulnerabilities, and deploy firewalls to restrict external access.

Updating endpoint protection like AhnLab V3 is crucial for preemptive malware detection. As threat actors increasingly pivot to open-source ecosystems, proactive monitoring via honeypots remains vital for intelligence gathering and threat mitigation.

Indicators of Compromise (IOCs)

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