{
  "family": "delfiles",
  "sample_count": 5,
  "category": "ransomware",
  "description": "Trojan:Win32/Delfiles is a persistent, stealthy trojan designed to breach endpoint defenses and securely deliver secondary, high-severity payloads like ransomware, banking trojans, and botnet agents, or act as a persistent backdoor. Its specific moniker suggests it may also have routines designed to delete specific system files or security logs to cover its tracks.<br><br><b>Understanding Delfiles</b><br>To an end-user, a Delfiles infection is typically invisible until the devastating secondary payload executes. For threat intelligence analysts, Delfiles 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, destructive payload.<br><br><b>Execution and Evasion Strategies</b><br>Delfiles is commonly distributed via massive malspam campaigns containing weaponized attachments (like ZIP files or Office macros) or through exploit kits. Upon execution, it utilizes heavy packing and dynamic API resolution to evade static antivirus signatures. It drops a randomized executable into the `%Temp%` or `%AppData%` directory. It establishes persistence by creating a hidden scheduled task or modifying the Registry Run keys. Delfiles frequently injects its downloading routine into legitimate system processes (like `explorer.exe` or `svchost.exe`) to mask its outbound network traffic. It may also execute commands to clear Windows Event Logs (`wevtutil cl System`) to hinder forensics.<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', particularly if followed by commands to delete files or clear logs. Network logs will often reveal Delfiles 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": [
    "T1566.001",
    "T1055",
    "T1105",
    "T1070.004",
    "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": "T1070.004",
      "name": "Indicator Removal: File Deletion",
      "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"
    }
  ],
  "containment_steps": [
    "Isolate the endpoint immediately to prevent Delfiles from downloading and executing its secondary payloads (e.g., ransomware).",
    "Audit the Windows Task Scheduler and Registry Run keys to identify and remove the Delfiles persistence mechanisms.",
    "Review firewall and proxy logs to identify the C2 domains Delfiles attempted to contact, and block them enterprise-wide.",
    "Capture a live memory image (RAM dump) to extract the injected Delfiles modules and identify the secondary payloads."
  ],
  "what_to_avoid": [
    "Do not close an incident simply because the initial Delfiles dropper was quarantined; always verify if secondary payloads were downloaded.",
    "Avoid relying solely on local Windows Event Logs for forensic analysis, as the malware may have successfully deleted or cleared them."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}