{
  "family": "cpuminer",
  "sample_count": 4,
  "category": "ransomware",
  "description": "Trojan:Win32/Cpuminer (often a generalized classification for multiple variants) represents a massive shift in cybercrime monetization: **Cryptojacking**. Instead of stealing data or demanding a ransom, Cpuminer silently hijacks the processing power (CPU/GPU) of the infected endpoint or server to mine cryptocurrency (most commonly Monero/XMR) and deposits the generated coins into the attacker's wallet.<br><br><b>Understanding Cpuminer (Cryptojacking)</b><br>To an end-user, a Cpuminer infection manifests as severe system sluggishness, loud cooling fans, and drastically reduced battery life on laptops. For an enterprise, a widespread cryptominer outbreak represents a massive theft of computing resources (driving up AWS/Azure cloud compute bills astronomically) and indicates a severe vulnerability that could easily be exploited to deploy ransomware instead.<br><br><b>Execution and Resource Hijacking Mechanics</b><br>Cpuminer variants are distributed via every conceivable vector: phishing, exploit kits, exposed RDP servers, and crucially, exploiting unpatched web servers (like WebLogic, Apache Struts, or vulnerable Docker APIs) (`T1190`). The payloads are often modified versions of open-source mining software like XMRig. Upon execution, the miner establishes persistence (via Scheduled Tasks or WMI event subscriptions) (`T1546.003`). It employs evasion tactics like 'Process Hollowing' (`T1055.012`) to hide the mining activity inside legitimate processes (like `svchost.exe` or `notepad.exe`). Advanced variants monitor Task Manager; if the user opens Task Manager to investigate the high CPU usage, the miner temporarily pauses its activity (`T1562.001`), resuming only when Task Manager is closed. The malware then utilizes nearly 100% of available CPU cycles (`T1496`) to calculate hashes, communicating continuously with a mining pool via the Stratum protocol (often over port 3333, 4444, or disguised as HTTPS/8080) (`T1071.001`).<br><br><b>Indicators of Compromise & Impact</b><br>The impact is hardware degradation, massive power consumption, and degraded server performance. Host-based IoCs include persistent 90-100% CPU usage by unrecognized or system processes, and EDR alerts for known mining command-line arguments (e.g., `-o stratum+tcp://... -u [wallet_address] -p x`). Network IoCs include continuous, long-lived connections to known mining pool domains (e.g., `minexmr.com`, `supportxmr.com`).",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1055.012",
    "T1071.001",
    "T1190",
    "T1496"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1496",
      "name": "Resource Hijacking (Cryptocurrency Mining)",
      "tactic": "Impact"
    },
    {
      "id": "T1055.012",
      "name": "Process Injection: Process Hollowing (Hiding the miner)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1071.001",
      "name": "Application Layer Protocol (Stratum mining protocol)",
      "tactic": "Command and Control"
    },
    {
      "id": "T1190",
      "name": "Exploit Public-Facing Application (Common entry vector for server miners)",
      "tactic": "Initial Access"
    }
  ],
  "containment_steps": [
    "Isolate the endpoint or server; if it is a cloud instance, immediately take a snapshot and then shut down the instance to halt the billing impact.",
    "Use EDR or Sysinternals Process Explorer to identify the specific process consuming the CPU and terminate it.",
    "Block known mining pool domains and Stratum protocol ports (3333, 4444, etc.) at the perimeter firewall.",
    "Investigate the initial vector: cryptominers on servers almost always indicate an unpatched vulnerability or an exposed management interface (like RDP or SSH)."
  ],
  "what_to_avoid": [
    "Do not dismiss high CPU alerts as just 'bad performance'; investigate them as potential security incidents.",
    "Avoid simply killing the process and moving on; most modern miners have watchdogs (secondary scheduled tasks) that will restart the miner immediately."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}