{
  "family": "filefinder",
  "sample_count": 4,
  "category": "ransomware",
  "description": "Spyware:Win32/Filefinder is a specialized information-stealing trojan designed explicitly for data exfiltration and reconnaissance. Unlike broad stealers that grab browser passwords, Filefinder acts more like a targeted search engine for the attacker, silently scanning the compromised file system and network shares for specific documents, databases, or intellectual property, and uploading them to a remote server.<br><br><b>Understanding Filefinder (Spyware/Data Stealers)</b><br>To an end-user, Filefinder is invisible; it does not display ransom notes or degrade performance significantly. For an enterprise, it represents a critical data breach. Attackers deploy Filefinder after gaining initial access to map the network and extract high-value data (like `.docx`, `.pdf`, `.sql`, `.key`, or custom proprietary extensions) before deploying a louder payload like ransomware.<br><br><b>Execution and Data Exfiltration Mechanics</b><br>Filefinder is typically deployed manually by an attacker who has already achieved interactive access (e.g., via RDP or a backdoor). It is designed to run quietly in the background. It utilizes native Windows APIs (like `FindFirstFile` and `FindNextFile`) (`T1083`) to aggressively traverse local drives and mapped SMB shares (`T1039`). It is often configured with a specific list of target file extensions or keywords. When matching files are found, it copies them to a hidden staging directory (`T1074.001`), often compressing and encrypting them into a single archive (like a password-protected `.zip` or `.rar`) (`T1560.001`). Finally, it exfiltrates the archive to the attacker's C2 server using FTP, HTTP POST requests, or cloud storage APIs (`T1048.003`).<br><br><b>Indicators of Compromise & Impact</b><br>The impact is a severe breach of confidentiality and intellectual property theft. Host-based IoCs include EDR alerts for anomalous, high-volume file read operations by an unknown executable, the creation of large, encrypted archive files in temporary directories (staging), and unexpected scheduled tasks used for persistence. Network IoCs involve large outbound data transfers to unknown IP addresses or unrecognized cloud storage providers.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1560.001",
    "T1074.001",
    "T1048.003",
    "T1083"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1083",
      "name": "File and Directory Discovery (Scanning the filesystem)",
      "tactic": "Discovery"
    },
    {
      "id": "T1074.001",
      "name": "Data Staged: Local Data Staging (Copying files to a temp folder)",
      "tactic": "Collection"
    },
    {
      "id": "T1560.001",
      "name": "Archive Collected Data: Archive via Utility (Compressing stolen data)",
      "tactic": "Collection"
    },
    {
      "id": "T1048.003",
      "name": "Exfiltration Over Alternative Protocol",
      "tactic": "Exfiltration"
    }
  ],
  "containment_steps": [
    "Isolate the endpoint immediately to halt any ongoing data exfiltration.",
    "Analyze the memory or the configuration file of the Filefinder executable to determine exactly which file types and directories were targeted.",
    "Review network egress logs to quantify the amount of data exfiltrated and identify the destination IP addresses/domains.",
    "Initiate incident response protocols for a confirmed data breach, as sensitive intellectual property or PII has likely been compromised."
  ],
  "what_to_avoid": [
    "Do not simply delete the malware and assume the incident is over; the primary damage (data theft) has likely already occurred, requiring a full breach investigation.",
    "Avoid rebooting the machine, as evidence of the staging directory or the active exfiltration connection may be lost."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}