{
  "name": "Chaos ransomware's msaRAT: Living off the browser to build a covert C2 channel",
  "slug": "chaos-ransomwares-msarat-living-off-the-browser-to-build-a-covert-c2-channel",
  "description": "Cisco Talos discovered msaRAT, a new Rust-based remote access trojan attributed to the Chaos ransomware group. This sophisticated RAT never directly touches the network, instead controlling command-and-control communications exclusively through Chrome DevTools Protocol (CDP). It manipulates browsers via CDP, performs signaling with Cloudflare Workers, and establishes WebRTC DataChannels using Twilio TURN as a relay. The infection chain begins with downloading an MSI file containing the RAT payload. msaRAT hijacks Chrome or Edge browsers in headless mode, injects JavaScript code, and establishes encrypted C2 communications through WebRTC. This design makes all external communications appear to originate from legitimate browser processes, effectively hiding C2 traffic within normal web activity and evading detection by firewalls and network monitoring tools.",
  "published": "2026-07-23T11:57:14.145000+00:00",
  "created_at": "2026-07-23T15:18:16.613000+00:00",
  "modified_at": null,
  "created_at_opencti": "2026-07-23T15:18:16.613000+00:00",
  "author": "AlienVault",
  "confidence": 100,
  "report_types": [
    "threat-report"
  ],
  "labels": [
    "browser hijacking",
    "chrome devtools protocol",
    "cloudflare workers",
    "covert tunneling",
    "msarat",
    "ransomware-as-a-service",
    "rust-based rat",
    "twilio turn",
    "webrtc"
  ],
  "tags": [],
  "related_entities": {
    "indicators": [
      {
        "id": "383bd8d6-49c7-4d80-91df-b54b06835240",
        "name": "http://172.86.126.18:443/update_ms.msi"
      },
      {
        "id": "90277869-f392-4f66-a0d4-825dcbfc643f",
        "name": "is-01-ast.ols-img-12.workers.dev"
      }
    ],
    "intrusion_sets": [
      {
        "id": "5bddec81-8efa-4323-9718-24c2c0ead1af",
        "name": "Chaos",
        "slug": "chaos"
      }
    ],
    "attack_patterns": [
      {
        "id": "6ccd4566-e15e-40cf-b7df-4a3f737ce5cd",
        "name": "T1036.005"
      },
      {
        "id": "32817170-4c07-427e-b8a5-80a733ae2550",
        "name": "T1497"
      },
      {
        "id": "93b2c4dd-5523-4464-8976-78754ee372fd",
        "name": "T1012"
      },
      {
        "id": "c3af9fd7-d307-4df4-9220-cc627938fb85",
        "name": "T1055"
      },
      {
        "id": "9322d33b-00c1-4f99-9f1a-a33d93c0dac2",
        "name": "T1059.007"
      },
      {
        "id": "840f859f-575f-487e-8083-6ffd01a13a84",
        "name": "T1218.007"
      },
      {
        "id": "c9ee9b30-ba84-4c24-95e9-e8242d42af3f",
        "name": "T1071.001"
      },
      {
        "id": "09124a92-c11f-4571-b35b-ab0bce6dd081",
        "name": "T1112"
      },
      {
        "id": "60972cf6-e90b-4600-af3c-13c468391d9c",
        "name": "T1106"
      },
      {
        "id": "0c836307-129e-4ff7-a532-180c633cacba",
        "name": "T1027"
      },
      {
        "id": "cbd87c8c-3bed-461a-acef-56ffc8b87571",
        "name": "T1105"
      },
      {
        "id": "c12e0e03-aab0-4646-a929-e921a3d27f02",
        "name": "T1219"
      },
      {
        "id": "9b6064e6-a05b-4e95-baf5-34d180bc9221",
        "name": "T1059"
      },
      {
        "id": "870bd958-53a3-4d25-9f23-00aa8bd6674d",
        "name": "T1102"
      },
      {
        "id": "14660ccf-ca6b-42f6-8bca-e1b7a04650b3",
        "name": "T1573.001"
      },
      {
        "id": "36d26fbc-439e-460e-bb28-0935ad0c1b8a",
        "name": "T1090.001"
      },
      {
        "id": "0156fcda-e385-4662-b388-086c3e16feec",
        "name": "T1140"
      },
      {
        "id": "a7262c61-4567-4a00-8cec-aae6264234a9",
        "name": "T1218"
      },
      {
        "id": "70616b2f-4019-4963-b758-5d9f6f20e201",
        "name": "T1082"
      },
      {
        "id": "fa3b8b48-d97c-4242-83a6-07d435a5a79e",
        "name": "T1041"
      }
    ],
    "malware": [
      {
        "id": "0eb46123-36f8-4a4c-b81f-e346f7661757",
        "name": "msaRAT"
      }
    ],
    "observables": [
      {
        "id": "7ca4249e-5626-4632-b3fc-a990767c134c",
        "name": "is-01-ast.ols-img-12.workers.dev"
      },
      {
        "id": "ac7cba98-1e11-43f6-a3c1-92ac245a104e",
        "name": "http://172.86.126.18:443/update_ms.msi"
      }
    ]
  },
  "external_refs": [
    {
      "id": "f134bebd-7095-4168-8711-6b0488a40d0a",
      "standard_id": "external-reference--0e3b9ff7-0dd0-5f63-9744-167553698355",
      "entity_type": "External-Reference",
      "source_name": "AlienVault",
      "description": null,
      "url": "https://otx.alienvault.com/pulse/6a62019ab2f0f4c8bf6527a0",
      "hash": null,
      "external_id": "6a62019ab2f0f4c8bf6527a0",
      "created": "2026-07-23T15:18:16.451Z",
      "modified": "2026-07-23T15:18:16.451Z",
      "createdById": null
    },
    {
      "id": "427700aa-a444-420b-9c46-2d64ab3e95d6",
      "standard_id": "external-reference--c36d6051-a34d-5efe-8a5d-22bc50b43257",
      "entity_type": "External-Reference",
      "source_name": "AlienVault",
      "description": null,
      "url": "https://blog.talosintelligence.com/chaos-msarat-living-off-the-browser-to-build-covert-c2-channel/",
      "hash": null,
      "external_id": null,
      "created": "2026-07-23T15:18:16.514Z",
      "modified": "2026-07-23T15:18:16.514Z",
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    }
  ]
}