{
  "id": "CB-UBU-NET-004",
  "standard": "ubuntu",
  "version": "main",
  "url": "https://baselines.cirsec.org/b/ubuntu/CB-UBU-NET-004",
  "json": "https://baselines.cirsec.org/b/ubuntu/CB-UBU-NET-004.json",
  "yaml": "https://baselines.cirsec.org/b/ubuntu/CB-UBU-NET-004.yml",
  "profiles_effective": [
    "server",
    "server-hardened",
    "desktop-hardened"
  ],
  "license": "Text CC BY 4.0, code Apache-2.0",
  "attribution": "CIRSEC Baselines, https://baselines.cirsec.org",
  "control": {
    "id": "CB-UBU-NET-004",
    "title": "Disable the Bluetooth service",
    "finding": {
      "title": "The Bluetooth service can be started",
      "description": "Bluetooth accepts connections from devices in radio range, outside any network control."
    },
    "status": "active",
    "profiles": [
      "server",
      "desktop-hardened"
    ],
    "risk": {
      "severity": "medium"
    },
    "assessment": "automated",
    "tags": [
      "bluetooth",
      "wireless",
      "service"
    ],
    "description": "On Ubuntu, Bluetooth is handled by `bluetoothd` from the `bluez` package, run by\n`bluetooth.service`. The package is installed on desktops and absent from server and cloud\nimages; when it is installed, the service starts as soon as an adapter is present. This\ncontrol requires the service to be masked, or `bluez` to be absent.\n",
    "rationale": "Bluetooth stacks have had remotely exploitable flaws reachable without pairing (BlueBorne,\nBleedingTooth). A server never needs Bluetooth, and a hardened workstation should not expose a\nradio interface that can be reached from a nearby room or car park.\n",
    "impact": "Bluetooth keyboards, mice, headsets and file transfer stop working.\n",
    "audit": {
      "manual": "Run `systemctl is-enabled bluetooth.service`. It must print `masked`, or fail because the unit\ndoes not exist (`bluez` not installed).\n",
      "checks": [
        {
          "id": "service",
          "engine": "systemd-unit",
          "description": "State of bluetooth.service.",
          "spec": {
            "unit": "bluetooth.service",
            "state": "masked"
          }
        }
      ]
    },
    "remediation": {
      "manual": "Run `systemctl mask --now bluetooth.service`, or remove the package with `apt purge bluez` when\nnothing depends on it.\n",
      "effects": {
        "restart": "none",
        "disruption": "low",
        "lockout_risk": false
      },
      "rollback": "Run `systemctl unmask bluetooth.service` and `systemctl start bluetooth.service`.\n",
      "scripts": [
        {
          "id": "mask",
          "from_check": "service"
        }
      ]
    },
    "references": [
      {
        "title": "bluetoothd(8), Ubuntu manual pages",
        "url": "https://manpages.ubuntu.com/manpages/noble/man8/bluetoothd.8.html",
        "publisher": "Canonical",
        "kind": "vendor-doc",
        "accessed": "2026-10-19"
      },
      {
        "title": "systemctl(1), Ubuntu manual pages",
        "url": "https://manpages.ubuntu.com/manpages/noble/man1/systemctl.1.html",
        "publisher": "Canonical",
        "kind": "vendor-doc",
        "accessed": "2026-10-19"
      }
    ],
    "mappings": [
      {
        "framework": "nist-800-53r5",
        "framework_version": "5.1.1",
        "id": "AC-18",
        "relation": "related"
      }
    ],
    "threats": [
      {
        "framework": "mitre-attack",
        "id": "T1011.001"
      },
      {
        "framework": "cwe",
        "id": "CWE-1188"
      }
    ],
    "authors": [
      {
        "name": "Alice",
        "github": "Sn0wAlice"
      }
    ],
    "verified": [
      {
        "date": "2026-10-19",
        "by": "Sn0wAlice",
        "versions": [
          "20.04"
        ],
        "environment": "Proxmox VM, Ubuntu 20.04 cloud image, kernel 5.4.0-216-generic, BIOS boot",
        "notes": "Server image without bluez, check passes (unit not found)."
      },
      {
        "date": "2026-10-19",
        "by": "Sn0wAlice",
        "versions": [
          "22.04"
        ],
        "environment": "Proxmox VM, Ubuntu 22.04 cloud image, kernel 5.15.0-198-generic, BIOS boot",
        "notes": "Server image without bluez, check passes (unit not found)."
      },
      {
        "date": "2026-10-19",
        "by": "Sn0wAlice",
        "versions": [
          "24.04"
        ],
        "environment": "Proxmox VM, Ubuntu 24.04 cloud image, kernel 6.8.0-147-generic, BIOS boot",
        "notes": "Server image without bluez, check passes (unit not found)."
      },
      {
        "date": "2026-10-19",
        "by": "Sn0wAlice",
        "versions": [
          "26.04"
        ],
        "environment": "Proxmox VM, Ubuntu 26.04 cloud image, kernel 7.0.0-38-generic, BIOS boot",
        "notes": "Passes without bluez; with bluez installed the service is reported enabled, then masked by the generated fix."
      }
    ],
    "introduced_in": "0.1.0",
    "created": "2026-10-19",
    "updated": "2026-10-19"
  }
}