{
  "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": [
    {
      "@type": "Question",
      "name": "What is Cpuminer and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Cpuminer is classified as a Ransomware. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments."
      }
    },
    {
      "@type": "Question",
      "name": "How does Cpuminer establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Cpuminer typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks."
      }
    },
    {
      "@type": "Question",
      "name": "What are the essential incident response steps for mitigating a Cpuminer compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Cpuminer should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups."
      }
    },
    {
      "@type": "Question",
      "name": "What cryptographic algorithms and file targeting techniques does Cpuminer employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Cpuminer typically leverages hybrid cryptographic architectures combining symmetric stream or block ciphers (such as AES-256 or ChaCha20) for rapid file encryption with asymmetric algorithms (such as RSA-2048 or Curve25519) to securely protect the session keys. It aggressively targets sensitive file extensions including corporate documents, databases, virtual disks, and backups while systematically executing commands to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet) and disable system recovery options."
      }
    },
    {
      "@type": "Question",
      "name": "Are decryptors available for Cpuminer, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Cpuminer depends on whether security researchers or law enforcement (such as the No More Ransom initiative) have recovered the master private keys or discovered flaws in its key generation routines. Victims should never pay the extortion demand, as payment fuels criminal operations without guaranteeing file restoration. The recommended recovery procedure entails isolating infected hosts, conducting forensic disk imaging, identifying the root access vector, and restoring validated systems from immutable offline backups."
      }
    }
  ],
  "faq_count": 5,
  "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": [
    "Healthcare",
    "Critical Infrastructure",
    "Enterprise"
  ],
  "motivation": "Financial Extortion",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "defense_evasion",
    "impact"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}