{
  "family": "hydracrypt",
  "sample_count": 180,
  "category": "ransomware",
  "description": "HydraCrypt is a destructive crypto-ransomware family that surfaced in early 2016, engineered directly from the leaked source code of the CrypBoss ransomware family (which also spawned its close sibling, UmbreCrypt). Primarily distributed through weaponized exploit kit redirects (such as the Angler Exploit Kit) and brute-forced Remote Desktop Protocol (RDP) entry points, HydraCrypt targets workstation endpoints and network-attached storage (NAS) devices. The ransomware enumerates drives and encrypts files utilizing a combination of AES-256 and RSA cryptography, appending extensions including '.hydracrypt' or random alphanumeric suffixes. Notably, flaws in HydraCrypt's file header manipulation implementation frequently damaged the last 15 bytes of encrypted files, rendering standard decryption difficult. However, cybersecurity researchers at Malwarebytes and Emsisoft exploited a severe vulnerability in the CrypBoss cryptographic key generation algorithm, successfully developing and publishing a free decryption tool that enabled victims to fully recover their files without paying the ransom extortion demand.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "HydraCrypt",
    "Ransomware:Win32/Hydracrypt",
    "CrypBoss.HydraCrypt",
    "UmbreCrypt"
  ],
  "enrichment_level": "curated_sourced",
  "faq": [
    {
      "@type": "Question",
      "name": "What is HydraCrypt ransomware?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "HydraCrypt is a crypto-ransomware strain based on the leaked CrypBoss codebase that encrypts user data and system files to demand cryptocurrency ransoms."
      }
    },
    {
      "@type": "Question",
      "name": "Can files encrypted by HydraCrypt be decrypted for free?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Yes. Security researchers at Emsisoft and Malwarebytes discovered cryptographic weaknesses in HydraCrypt's key scheduler and published a free offline decryption tool."
      }
    },
    {
      "@type": "Question",
      "name": "How did HydraCrypt infect systems?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "HydraCrypt was primarily delivered via drive-by downloads using the Angler Exploit Kit and compromised Remote Desktop Protocol (RDP) endpoints."
      }
    },
    {
      "@type": "Question",
      "name": "Why did HydraCrypt corrupt some files during encryption?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Due to a programming bug in its file-processing loop, HydraCrypt overwrote the final 15 bytes of certain encrypted files, damaging file structures even if a ransom was paid."
      }
    },
    {
      "@type": "Question",
      "name": "What should victims do if infected with HydraCrypt?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Victims should disconnect from the network, back up encrypted files (do not delete them), download the official Emsisoft/Malwarebytes CrypBoss decryptor, and restore corrupted file headers."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1486",
    "T1490",
    "T1083",
    "T1547.001",
    "T1189",
    "T1071.001"
  ],
  "mitre_attack_detail": [
    {
      "id": "T1486",
      "name": "Data Encrypted for Impact",
      "tactic": "impact"
    },
    {
      "id": "T1490",
      "name": "Inhibit System Recovery",
      "tactic": "impact"
    },
    {
      "id": "T1083",
      "name": "File and Directory Discovery",
      "tactic": "discovery"
    },
    {
      "id": "T1547.001",
      "name": "Registry Run Keys / Startup Folder",
      "tactic": "persistence"
    },
    {
      "id": "T1189",
      "name": "Drive-by Compromise",
      "tactic": "initial-access"
    },
    {
      "id": "T1071.001",
      "name": "Web Protocols",
      "tactic": "command-and-control"
    }
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-16",
  "first_seen": 2016,
  "lineage": {
    "derived_from": [
      "crypboss leaked source"
    ],
    "variants": [
      "umbrecrypt",
      "hydracrypt 1.0"
    ]
  },
  "attribution": [
    {
      "actor": "CrypBoss / HydraCrypt Group",
      "confidence": "medium"
    }
  ],
  "exploited_cves": [],
  "c2_profile": {
    "protocols": [
      "HTTP",
      "Tor"
    ],
    "ports": [
      80,
      443
    ],
    "traffic_identifiability": "medium"
  },
  "iocs": {
    "file_hashes": [
      "b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2",
      "a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1"
    ],
    "delivery": [
      "angler_exploit_kit",
      "rdp_brute_force"
    ],
    "persistence": [
      "HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Run"
    ]
  },
  "sources": [
    {
      "name": "Malwarebytes Labs: Decrypted - HydraCrypt and UmbreCrypt Ransomware",
      "url": "https://www.malwarebytes.com/blog/news/2016/02/decrypted-hydracrypt-and-umbrecrypt"
    },
    {
      "name": "BleepingComputer: HydraCrypt Ransomware Dissected and Decrypted",
      "url": "https://www.bleepingcomputer.com/news/security/hydracrypt-ransomware-has-been-decrypted-instructions-here/"
    },
    {
      "name": "Emsisoft Decryption Tools: CrypBoss / HydraCrypt",
      "url": "https://www.emsisoft.com/en/ransomware-decryption/"
    }
  ],
  "containment_steps": [
    "Isolate compromised systems immediately from local networks and shared storage.",
    "Retain encrypted files and do not pay the ransom, as a free Emsisoft decryptor is available.",
    "Audit remote desktop configurations and close public port 3389 exposure.",
    "Run an offline scanner to eliminate any persistence hooks or staging payloads."
  ],
  "what_to_avoid": [
    "Do not pay the extortion demand, as the encryption key is fully crackable with free tools.",
    "Avoid modifying or attempting to repair corrupted file headers without making a backup copy first.",
    "Never expose un-authenticated Remote Desktop Protocol interfaces to the public internet."
  ],
  "target_industries": [
    "consumers",
    "small_business",
    "education"
  ],
  "motivation": "Financial Extortion via Ransomware",
  "threat_actors": [
    "HydraCrypt Authors"
  ],
  "target_geographies": [
    "GLOBAL",
    "US",
    "EU"
  ],
  "attack_stage": [
    "initial-access",
    "execution",
    "persistence",
    "impact"
  ],
  "ecosystem": [
    "windows"
  ],
  "is_emerging": false,
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}