V3G4 Botnet Evolves: From DDoS to Covert Cryptomining
Summary:
Cyble Research & Intelligence Labs (CRIL) has identified an active Linux-targeting campaign, dubbed V3G4, that signifies the ongoing, financially-motivated evolution of Mirai-lineage threats by coupling DDoS capabilities with covert monetization. CRIL's investigation details a multi-stage infection chain that begins with a "Universal Bot Downloader" shell script, which automatically detects the target system's architecture to deliver a matching, UPX-packed bot binary across x86_64, ARM, and MIPS systems for broad compatibility. Once executed, the bot initiates aggressive stealth and evasion tactics, including: masquerading its process name as a legitimate system service, detaching from the terminal, and using a localhost TCP socket for internal IPC to blend in with normal system traffic. Furthermore, the botnet aggressively performs raw TCP socket SSH scanning across the Internet for propagation and utilizes multi-threaded DNS queries against 8.8.8.8 to maintain a resilient connection to its C2 domain. Most notably, the campaign deploys a final stage XMRig-based Monero miner that utilizes dynamic, fileless configuration, where all mining parameters, such as the wallet address and pool URL, are fetched at runtime directly from the C2 server, thereby preventing the exposure of key data points during static analysis and significantly hindering forensic efforts.
Security Officer Comments:
This V3G4 campaign represents a significant marker in the ongoing evolution of Mirai-lineage threats, demonstrating the threat actor's clear intent to maximize return on investment through a hybrid monetization strategy that combines traditional DDoS capability with covert cryptomining. Analysts see the complexity of the execution chain, from the Universal Bot Downloader customizing the payload for diverse architectures (x86_64, ARM, MIPS) to the final cryptominer execution, as evidence of a mature and professional operation focused on broad Linux and IoT compromise.
Suggested Corrections:
Cyble researchers have published the following mitigations to help detect and defend against the V3G4 Botnet:
1. Harden External Attack Surface
2. Monitor for Anomalous Network Activity
3. Deploy File Integrity & Runtime Monitoring
4. Strengthen Cloud and Linux Security Posture
5. Proactive Threat Hunting
6. Patch and Update Regularly
Link(s):
https://cyble.com/blog/v3g4-mirai-botnet-evolves/
Cyble Research & Intelligence Labs (CRIL) has identified an active Linux-targeting campaign, dubbed V3G4, that signifies the ongoing, financially-motivated evolution of Mirai-lineage threats by coupling DDoS capabilities with covert monetization. CRIL's investigation details a multi-stage infection chain that begins with a "Universal Bot Downloader" shell script, which automatically detects the target system's architecture to deliver a matching, UPX-packed bot binary across x86_64, ARM, and MIPS systems for broad compatibility. Once executed, the bot initiates aggressive stealth and evasion tactics, including: masquerading its process name as a legitimate system service, detaching from the terminal, and using a localhost TCP socket for internal IPC to blend in with normal system traffic. Furthermore, the botnet aggressively performs raw TCP socket SSH scanning across the Internet for propagation and utilizes multi-threaded DNS queries against 8.8.8.8 to maintain a resilient connection to its C2 domain. Most notably, the campaign deploys a final stage XMRig-based Monero miner that utilizes dynamic, fileless configuration, where all mining parameters, such as the wallet address and pool URL, are fetched at runtime directly from the C2 server, thereby preventing the exposure of key data points during static analysis and significantly hindering forensic efforts.
Security Officer Comments:
This V3G4 campaign represents a significant marker in the ongoing evolution of Mirai-lineage threats, demonstrating the threat actor's clear intent to maximize return on investment through a hybrid monetization strategy that combines traditional DDoS capability with covert cryptomining. Analysts see the complexity of the execution chain, from the Universal Bot Downloader customizing the payload for diverse architectures (x86_64, ARM, MIPS) to the final cryptominer execution, as evidence of a mature and professional operation focused on broad Linux and IoT compromise.
Suggested Corrections:
Cyble researchers have published the following mitigations to help detect and defend against the V3G4 Botnet:
1. Harden External Attack Surface
- Disable password-based SSH authentication; enforce key-based access.
- Apply rate-limiting or geo-restrictions on SSH (port 22).
- Ensure unnecessary internet-exposed services are closed.
2. Monitor for Anomalous Network Activity
- Detect raw TCP packet floods targeting port 22.
- Monitor for unusual outbound connections to suspicious IPs and domains.
3. Deploy File Integrity & Runtime Monitoring
- Alert on download + execution of binaries from /tmp or /dev/shm.
- Detect unusual process names such as systemd-logind originating from non-system paths.
- Monitor for UPX-packed ELF binaries on endpoints.
4. Strengthen Cloud and Linux Security Posture
- Enable SELinux/AppArmor enforcement.
- Restrict write/execute permissions on temporary filesystems.
- Implement EDR solutions capable of analyzing Linux process behavior.
5. Proactive Threat Hunting
- Hunt for evidence of XMRig execution.
- Search for traces of raw-socket creation or SYN-flood-like behavior.
- Inspect systems for masqueraded processes or hidden botnet listeners (e.g., 127.0.0.1:63841).
6. Patch and Update Regularly
- Ensure Linux kernels, SSH services, and IoT firmware remain up to date, closing vulnerabilities exploited by botnet operators.
Link(s):
https://cyble.com/blog/v3g4-mirai-botnet-evolves/