{
  "family": "hydracrypt",
  "sample_count": 2,
  "category": "ransomware",
  "description": "Ransomware:Win32/Hydracrypt is a destructive crypto-ransomware family designed to extort organizations by encrypting critical data and demanding payment in cryptocurrency for the decryption key. It is closely related to the UmbreCrypt ransomware family and gained notoriety for a flaw in its encryption implementation that allowed security researchers to eventually build a free decryption tool.<br><br><b>Understanding Hydracrypt (Ransomware)</b><br>To an end-user, a Hydracrypt infection is catastrophic. Files become inaccessible, their extensions are changed (e.g., appended with `.hydracrypt_ID_...`), and a text or HTML file drops onto the desktop demanding a ransom. For an enterprise, it represents a massive incident requiring immediate disaster recovery protocols. The attackers leverage encryption (`T1486`) to ensure data recovery is impossible without the attacker's key (or a known decryptor).<br><br><b>Execution and Extortion Mechanics</b><br>Hydracrypt is typically distributed via Exploit Kits (like Angler) (`T1189`) or malspam campaigns. Upon execution, the malware rapidly disables local recovery options (`T1490`) by executing `vssadmin.exe Delete Shadows /All /Quiet`. It then traverses local drives and mapped network shares, encrypting files matching specific extensions. It utilizes a flawed implementation of AES encryption, appending a unique victim ID to the file extension. Finally, it drops the ransom note (`T1491.001`), usually named `README_DECRYPT_HYDRA.txt`, providing instructions on how to pay the ransom via a Tor hidden service.<br><br><b>Indicators of Compromise & Impact</b><br>The impact is severe business disruption and potential data loss. Host-based IoCs include EDR alerts for rapid, mass file modifications (`T1486`), the execution of `vssadmin.exe` to destroy backups, and the presence of files with `.hydracrypt` appended to the extension. The creation of the `README_DECRYPT_HYDRA` ransom notes is a definitive indicator. Network IoCs may include the initial dropper communicating with Exploit Kit infrastructure or the ransom portal over Tor.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1490",
    "T1486",
    "T1189"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1486",
      "name": "Data Encrypted for Impact (The core ransomware action)",
      "tactic": "Impact"
    },
    {
      "id": "T1490",
      "name": "Inhibit System Recovery (Deleting Volume Shadow Copies)",
      "tactic": "Impact"
    },
    {
      "id": "T1189",
      "name": "Drive-by Compromise (Distribution via Exploit Kits)",
      "tactic": "Initial Access"
    }
  ],
  "containment_steps": [
    "IMMEDIATELY isolate the infected machine from the network (unplug the Ethernet cable) to halt the encryption of mapped network shares.",
    "Do NOT pay the ransom; Hydracrypt has known flaws, and free decryption tools (like those from Emsisoft) are available.",
    "Identify the initial infection vector (e.g., outdated browser plugin exploited by an EK) and patch it enterprise-wide.",
    "Utilize the free decryptor tools to restore data, or restore from offline, immutable backups."
  ],
  "what_to_avoid": [
    "Do not reboot or power off the machine immediately if a live memory capture is possible, as the encryption keys might temporarily reside in RAM.",
    "Do not connect backup drives or network shares to an infected machine to 'check' the data, as the ransomware will encrypt the backups."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}