{
  "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": [
    {
      "@type": "Question",
      "name": "What is Filefinder and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Filefinder 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 Filefinder establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Filefinder 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 Filefinder compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Filefinder 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 Filefinder employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Filefinder 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 Filefinder, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Filefinder 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": [
    "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": [
    "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"
  ]
}