{
  "family": "hiddentears",
  "sample_count": 2,
  "category": "ransomware",
  "description": "Ransomware:Win32/Hiddentears is a highly significant case study in malware history. It was originally released on GitHub in August 2015 by a Turkish programmer as an 'educational' open-source ransomware project. Predictably, it was immediately weaponized by low-skill threat actors ('script kiddies'), spawning hundreds of real-world ransomware variants (like MoWare, Cryptear, and KryptoLocker). It demonstrates the extreme danger of publishing destructive code, regardless of intent (`T1486`).<br><br><b>Understanding Hiddentears (Open-Source Ransomware)</b><br>To an end-user, a HiddenTears-based infection looks like standard ransomware: files are encrypted, extensions are changed (often to `.locked` or `.hiddentears`), and a text-based ransom note appears on the desktop. For an incident response team, identifying a variant as based on HiddenTears is often a relief, as the original encryption implementation contained fatal flaws that allow for free decryption.<br><br><b>Execution and Cryptographic Flaws</b><br>HiddenTears variants are typically distributed via low-effort malspam or dropped by other generic trojans. Upon execution, it scans the user's directories and uses AES-256 encryption (`T1486`) to lock specific file types. It communicates the encryption key to a C2 server (often a simple web panel) (`T1041`). Crucially, the original open-source code utilized a fundamentally flawed method for generating the AES key and Initialization Vector (IV). It used the standard `Random` class seeded with a predictable timestamp, allowing cryptographic researchers to easily brute-force the seed and reverse the encryption without paying the ransom.<br><br><b>Indicators of Compromise & Impact</b><br>The primary impact is data unavailability. Host-based IoCs include files appended with unusual extensions, the presence of ransom notes (often named `READ_IT.txt` or similar), and high CPU utilization by an unknown process during the encryption phase. A key indicator of a HiddenTears variant is often the presence of specific hardcoded strings from the original open-source project within the executable's memory.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Hiddentears and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Hiddentears 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 Hiddentears establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Hiddentears 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 Hiddentears compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Hiddentears 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 Hiddentears employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Hiddentears 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 Hiddentears, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Hiddentears 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": [
    "T1041",
    "T1486",
    "T1059.003"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1486",
      "name": "Data Encrypted for Impact (The core ransomware payload)",
      "tactic": "Impact"
    },
    {
      "id": "T1041",
      "name": "Exfiltration Over C2 Channel (Transmitting the generated encryption key back to the attacker)",
      "tactic": "Exfiltration"
    },
    {
      "id": "T1059.003",
      "name": "Command and Scripting Interpreter: Windows Command Shell (Often used to delete shadow copies)",
      "tactic": "Execution"
    }
  ],
  "containment_steps": [
    "Immediately disconnect the infected machine from the network to prevent the ransomware from reaching network shares.",
    "Do not pay the ransom. Immediately search reputable security vendor sites (like NoMoreRansom) for a HiddenTears decryptor tool.",
    "Preserve the infected system in its current state; rebooting might destroy artifacts needed by the free decryption tools.",
    "Identify and patch the initial entry vector (often weak RDP credentials or malicious email attachments)."
  ],
  "what_to_avoid": [
    "Do not assume the data is lost forever; HiddenTears is notoriously flawed, and free decryption tools are widely available.",
    "Avoid paying the ransom; dealing with script kiddies using open-source tools rarely results in successful decryption."
  ],
  "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"
  ]
}