{
  "Event": {
    "analysis": "1",
    "date": "2026-04-21",
    "extends_uuid": "",
    "info": "[Threat Intel] Kyber Ransomware Double Trouble: Windows and ESXi Attacks Explained",
    "protected": false,
    "publish_timestamp": "1779544380",
    "published": true,
    "threat_level_id": "2",
    "timestamp": "1779544379",
    "uuid": "d2fe5bb3-1436-4e42-a595-cf13e3e94bb9",
    "Orgc": {
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      "uuid": "cd9bd516-61fa-476b-980f-2f8de03992d4"
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        "name": "misp-galaxy:producer=\"Rapid7\"",
        "relationship_type": ""
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        "local": false,
        "name": "tlp:clear",
        "relationship_type": ""
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        "local": false,
        "name": "type:OSINT",
        "relationship_type": ""
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      {
        "colour": "#b94b1d",
        "local": false,
        "name": "rectifyq:mitre-att&ck=\"from-original-src\"",
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      {
        "colour": "#b94b1d",
        "local": false,
        "name": "rectifyq:mitre-att&ck=\"from-OTX\"",
        "relationship_type": ""
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        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Windows Management Instrumentation - T1047\"",
        "relationship_type": ""
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      {
        "colour": "#b2a633",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Service Stop - T1489\"",
        "relationship_type": ""
      },
      {
        "colour": "#5c57c8",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Windows Service - T1543.003\"",
        "relationship_type": ""
      },
      {
        "colour": "#aad818",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"SSH - T1021.004\"",
        "relationship_type": ""
      },
      {
        "colour": "#d528b5",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Windows File and Directory Permissions Modification - T1222.001\"",
        "relationship_type": ""
      },
      {
        "colour": "#7d7034",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"System Information Discovery - T1082\"",
        "relationship_type": ""
      },
      {
        "colour": "#f5a258",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Native API - T1106\"",
        "relationship_type": ""
      },
      {
        "colour": "#0088cc",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Indirect Command Execution - T1202\"",
        "relationship_type": ""
      },
      {
        "colour": "#bf01b7",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Modify Registry - T1112\"",
        "relationship_type": ""
      },
      {
        "colour": "#0088cc",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Clear Windows Event Logs - T1070.001\"",
        "relationship_type": ""
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        "colour": "#0c0051",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"File and Directory Discovery - T1083\"",
        "relationship_type": ""
      },
      {
        "colour": "#1cbe6b",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Virtualization/Sandbox Evasion - T1497\"",
        "relationship_type": ""
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        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"PowerShell - T1059.001\"",
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        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Disable or Modify Tools - T1562.001\"",
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        "name": "misp-galaxy:mitre-attack-pattern=\"Obfuscated Files or Information - T1027\"",
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        "colour": "#36d931",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Data Encrypted for Impact - T1486\"",
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      },
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        "colour": "#a05856",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Data Destruction - T1485\"",
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        "colour": "#297c25",
        "local": false,
        "name": "misp-galaxy:mitre-attack-pattern=\"Inhibit System Recovery - T1490\"",
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      },
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        "local": false,
        "name": "rectifyq:category=\"threat\"",
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      },
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        "local": false,
        "name": "rectifyq:sub-category=\"TA-profile\"",
        "relationship_type": ""
      },
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        "colour": "#f1dfed",
        "local": false,
        "name": "rectifyq:TA-category=\"Ransomware\"",
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      },
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        "colour": "#ffd12e",
        "local": false,
        "name": "rectifyq:target=\"broad-based\"",
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        "colour": "#55acee",
        "local": false,
        "name": "rectifyq:MY-relevancy=\"potentially-relevant\"",
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      },
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        "colour": "#0088cc",
        "local": false,
        "name": "misp-galaxy:ransomware=\"kyber\"",
        "relationship_type": ""
      },
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        "local": false,
        "name": "rectifyq:no-samples-in=\"MalwareBazaar\"",
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      },
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        "name": "rectifyq:action-taken=\"VT-comment\"",
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    ],
    "Attribute": [
      {
        "category": "External analysis",
        "comment": "",
        "deleted": false,
        "disable_correlation": false,
        "timestamp": "1776913214",
        "to_ids": false,
        "type": "link",
        "uuid": "053c11ad-1a8c-4eec-ab61-99877ea7e718",
        "value": "https://www.rapid7.com/blog/post/tr-kyber-ransomware-double-trouble-windows-esxi-attacks-explained/"
      },
      {
        "category": "Other",
        "comment": "Description",
        "deleted": false,
        "disable_correlation": false,
        "timestamp": "1776913214",
        "to_ids": false,
        "type": "text",
        "uuid": "1abe0f34-d134-400f-96dd-54601c42d9a9",
        "value": "Kyber ransomware represents a significant threat through dual-platform deployment capabilities targeting VMware ESXi virtualization infrastructure and Windows file systems. During a March 2026 incident response engagement, two Kyber payloads were recovered from the same environment. The ESXi variant, written in C++, specifically targets VMware environments with datastore encryption, VM termination, and management interface defacement capabilities. The Windows variant, written in Rust, includes experimental Hyper-V targeting features. Both samples share campaign identifiers and Tor-based infrastructure, confirming coordinated cross-platform operations. Despite advertising post-quantum Kyber1024 encryption, the ESXi variant actually uses ChaCha8 with RSA-4096 key wrapping, while the Windows variant implements the claimed AES-256-CTR with Kyber1024 hybrid scheme. The ransomware includes anti-recovery measures, service termination, and effective encryption strategies designed to cause complete operational disr..."
      },
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        "category": "Other",
        "comment": "Summary",
        "deleted": false,
        "disable_correlation": false,
        "timestamp": "1776913214",
        "to_ids": false,
        "type": "text",
        "uuid": "ed464d67-037b-47b1-8c8d-2cb164bdfe7c",
        "value": "Name: Kyber Ransomware Double Troubl%WINDIR%\\and ESXi Attacks Explained\nAuthor: AlienVault\nAdversary: Kyber\nTags: [\"rust\", \"virtualization\", \"chacha8\", \"hyper-v\", \"vmware\", \"esxi\", \"cross-platform\", \"kyber\"]\nTgtd countries: []\nMlwr families: [\"Kyber\"]\nAttack_ids: [\"T1047\", \"T1489\", \"T1543.003\", \"T1021.004\", \"T1222.001\", \"T1082\", \"T1106\", \"T1202\", \"T1112\", \"T1070.001\", \"T1083\", \"T1497\", \"T1059.001\", \"T1562.001\", \"T1027\", \"T1486\", \"T1485\", \"T1569.002\", \"T1490\"]\nIndustries: []"
      },
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        "category": "Attribution",
        "comment": "Adversary",
        "deleted": false,
        "disable_correlation": false,
        "timestamp": "1776913214",
        "to_ids": false,
        "type": "threat-actor",
        "uuid": "c9919697-7aa4-4a38-89f0-a5758f0f5171",
        "value": "Kyber"
      },
      {
        "category": "Payload delivery",
        "comment": "Windows Rust Binary No sample in VT\r\nLast check:26/04/2026",
        "deleted": false,
        "disable_correlation": false,
        "timestamp": "1779544378",
        "to_ids": true,
        "type": "sha256",
        "uuid": "b12abfd5-c6d1-4df7-b4d8-e37b1f6eb3b7",
        "value": "45bff0df2c408b3f589aed984cc331b617021ecbea57171dac719b5f545f5e8d",
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            "local": false,
            "name": "rectifyq:ioc=\"enriched\"",
            "relationship_type": ""
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            "local": false,
            "name": "rectifyq:no-samples-in=\"VirusTotal\"",
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            "local": false,
            "name": "rectifyq:no-samples-in=\"Tria.ge\"",
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            "name": "rectifyq:no-samples-in=\"MalwareBazaar\"",
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          }
        ]
      },
      {
        "category": "Payload delivery",
        "comment": "Linux/ESXi ELF Binary No sample in VT\r\nLast check:26/04/2026",
        "deleted": false,
        "disable_correlation": false,
        "timestamp": "1779544379",
        "to_ids": true,
        "type": "sha256",
        "uuid": "10df1b26-dcd0-4378-88a1-8f67929ef18a",
        "value": "6ccacb7567b6c0bd2ca8e68ff59d5ef21e8f47fc1af70d4d88a421f1fc5280fc",
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        "description": "File object describing a file with meta-information",
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            "comment": "Old Windows Variant",
            "deleted": false,
            "disable_correlation": false,
            "object_relation": "md5",
            "timestamp": "1779544375",
            "to_ids": true,
            "type": "md5",
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            "disable_correlation": false,
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            "object_relation": "ssdeep",
            "timestamp": "1777213375",
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            "category": "Other",
            "comment": "",
            "deleted": false,
            "disable_correlation": true,
            "object_relation": "size-in-bytes",
            "timestamp": "1777213375",
            "to_ids": false,
            "type": "size-in-bytes",
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          },
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            "comment": "",
            "deleted": false,
            "disable_correlation": false,
            "object_relation": "vhash",
            "timestamp": "1777213375",
            "to_ids": true,
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          },
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            "comment": "",
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            "comment": "Checked: 26/04/2026\nLast-scan\t:  25/04/2026",
            "deleted": false,
            "disable_correlation": true,
            "object_relation": "text",
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}