{
  "family": "hiddentear",
  "sample_count": 8,
  "category": "ransomware",
  "description": "Ransom:Win32/Hiddentear is a highly significant ransomware family in cybersecurity history. Originally developed by a Turkish researcher in 2015 and released on GitHub as an 'open-source educational project', HiddenTear was intended to demonstrate how ransomware works. Predictably, it was immediately co-opted by script kiddies and low-tier cybercriminals, who slightly modified the source code to spawn hundreds of real-world ransomware variants, causing widespread damage.<br><br><b>Understanding HiddenTear</b><br>To a victim, a HiddenTear infection is indistinguishable from top-tier ransomware; their files are encrypted, a unique extension (e.g., `.locked`) is appended, and a ransom note demands Bitcoin. For a security analyst, a HiddenTear detection often indicates a less sophisticated adversary. Because the original source code was flawed—specifically, the random number generator used for the encryption keys was extremely weak—files encrypted by many early HiddenTear variants can actually be decrypted for free using publicly available tools.<br><br><b>Execution and Encryption Mechanics</b><br>Because the source code is public, the distribution vector varies wildly, ranging from spam emails (`T1566.001`) to malicious Discord links (`T1189`). Upon execution (`T1204.002`), the malware typically establishes persistence by dropping a copy of itself in the `%AppData%` or `%LocalAppData%` directory and creating a Registry Run key (`T1547.001`). The core encryption routine targets a hardcoded list of file extensions (documents, images, databases) using AES encryption (`T1486`). In the original code, the encryption key was sent in plaintext to a web server via an HTTP GET request (`T1041`). It then drops a simple text file (`READ_IT.txt`) on the desktop detailing the ransom demand.<br><br><b>Indicators of Compromise & Impact</b><br>The impact is significant data loss and disruption. The primary IoC is the sudden renaming of files to include anomalous extensions (which vary wildly depending on the script kiddie who compiled it) and the appearance of the ransom note. Network analysts might observe an HTTP GET request containing a string of characters (the AES key) being sent to a suspicious, often free-hosting, web domain. Static analysis of the executable will often reveal it is compiled in .NET and heavily resembles the public GitHub repository.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Hiddentear and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Hiddentear 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 Hiddentear establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Hiddentear 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 Hiddentear compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Hiddentear 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 Hiddentear employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Hiddentear 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 Hiddentear, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Hiddentear 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": [
    "T1486",
    "T1547.001",
    "T1041",
    "T1204.002"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1486",
      "name": "Data Encrypted for Impact",
      "tactic": "Impact"
    },
    {
      "id": "T1547.001",
      "name": "Boot or Logon Autostart Execution: Registry Run Keys",
      "tactic": "Persistence"
    },
    {
      "id": "T1041",
      "name": "Exfiltration Over C2 Channel (Sending the AES key)",
      "tactic": "Exfiltration"
    },
    {
      "id": "T1204.002",
      "name": "User Execution: Malicious File",
      "tactic": "Execution"
    }
  ],
  "containment_steps": [
    "Instantly isolate the infected endpoint from the network to halt the encryption process, specifically protecting mapped network shares.",
    "Do NOT reboot the machine immediately; capture a live memory dump (RAM) first, as poorly coded variants often leave the AES key in memory.",
    "Crucially, identify the specific variant of HiddenTear (based on the extension and ransom note) and check 'NoMoreRansom.org'; a vast majority of these variants have free decryption tools available.",
    "If no decryptor is available, restore the affected systems from secure, offline backups."
  ],
  "what_to_avoid": [
    "Do not pay the ransom. HiddenTear operators are often inexperienced script kiddies who frequently lose the C2 infrastructure or the keys, meaning paying rarely results in file recovery.",
    "Avoid assuming the encryption is unbreakable; the cryptographic flaws in the original source code persist in many wild variants."
  ],
  "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"
  ]
}