# yaml-language-server: $schema=../../../../schema/control.schema.json
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
  `bluetooth.service`. The package is installed on desktops and absent from server and cloud
  images; when it is installed, the service starts as soon as an adapter is present. This
  control requires the service to be masked, or `bluez` to be absent.
rationale: |
  Bluetooth stacks have had remotely exploitable flaws reachable without pairing (BlueBorne,
  BleedingTooth). A server never needs Bluetooth, and a hardened workstation should not expose a
  radio interface that can be reached from a nearby room or car park.
impact: |
  Bluetooth keyboards, mice, headsets and file transfer stop working.

audit:
  manual: |
    Run `systemctl is-enabled bluetooth.service`. It must print `masked`, or fail because the unit
    does not exist (`bluez` not installed).
  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
    nothing depends on it.
  effects:
    restart: none
    disruption: low
    lockout_risk: false
  rollback: |
    Run `systemctl unmask bluetooth.service` and `systemctl start bluetooth.service`.
  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
  - framework: cis-ubuntu-2004
    framework_version: "3.0.0"
    id: "3.1.3"
    relation: equivalent
  - framework: cis-ubuntu-2204
    framework_version: "3.0.0"
    id: "3.1.3"
    relation: equivalent
  - framework: cis-ubuntu-2404
    framework_version: "2.0.0"
    id: "3.1.3"
    relation: equivalent
  - framework: cis-ubuntu-2604
    framework_version: "1.0.0"
    id: "3.1.3"
    relation: equivalent
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