{
  "family": "nymeria",
  "sample_count": 102,
  "category": "ransomware",
  "description": "TrojanDownloader:Win32/Nymeria is a persistent, heavily obfuscated trojan designed to breach endpoint defenses and securely deliver secondary, high-severity payloads, frequently operating as a precursor to devastating ransomware deployments.<br><br><b>Understanding Nymeria</b><br>To an end-user, a Nymeria infection is typically invisible until the secondary payload (like ransomware locking the screen) executes. For threat intelligence analysts, Nymeria is a critical staging mechanism. It functions as an 'Initial Access Broker' tool. Its primary objective is to securely bypass endpoint defenses, profile the infected machine to ensure it is not a sandbox, and reach out to a Command-and-Control (C2) server to pull down the final payload.<br><br><b>Execution and Evasion Strategies</b><br>Nymeria is commonly distributed via massive malspam campaigns containing weaponized attachments (like ZIP files or Office macros). Upon execution, it utilizes heavy packing and dynamic API resolution to evade static antivirus signatures. It drops a randomized executable into the `%Temp%` directory. It establishes persistence by creating a hidden scheduled task or modifying the Registry Run keys. Nymeria frequently injects its downloading routine into legitimate system processes (like `explorer.exe` or `svchost.exe`) to mask its outbound network traffic.<br><br><b>Indicators of Compromise (IoCs)</b><br>Threat hunters should investigate EDR alerts related to 'Suspicious Process Injection' or 'Anomalous Child Process Spawning'. Network logs will often reveal Nymeria reaching out to compromised domains using encrypted HTTPS traffic. The presence of unexpected, hidden scheduled tasks designed to execute randomly named binaries in the user's profile is a strong IoC. Memory analysis is necessary to extract the injected downloader modules and determine what payloads were requested.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1027",
    "T1566.001",
    "T1055",
    "T1105",
    "T1547.001"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer",
      "tactic": "Command and Control"
    },
    {
      "id": "T1055",
      "name": "Process Injection",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1547.001",
      "name": "Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder",
      "tactic": "Persistence"
    },
    {
      "id": "T1566.001",
      "name": "Phishing: Spearphishing Attachment",
      "tactic": "Initial Access"
    },
    {
      "id": "T1027",
      "name": "Obfuscated Files or Information",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Isolate the endpoint immediately to prevent Nymeria from downloading and executing its secondary payloads (e.g., ransomware).",
    "Audit the Windows Task Scheduler and Registry Run keys to identify and remove the Nymeria persistence mechanisms.",
    "Review firewall and proxy logs to identify the C2 domains Nymeria attempted to contact, and block them enterprise-wide.",
    "Capture a live memory image (RAM dump) to extract the injected Nymeria modules and identify the secondary payloads."
  ],
  "what_to_avoid": [
    "Do not close an incident simply because the initial Nymeria dropper was quarantined; always verify if secondary payloads were downloaded.",
    "Avoid relying solely on manual file deletion, as the injected processes will likely just recreate the dropped binaries."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}