# yaml-language-server: $schema=../../../../schema/control.schema.json
id: CB-DEB-SVC-023
title: Disable the CUPS print server and printer discovery
finding:
  title: The CUPS print service runs on a system that does not print
  description: CUPS and cups-browsed parse print jobs and printer announcements, and have had remotely exploitable flaws.
status: active
profiles: [server, desktop-hardened]
risk:
  severity: medium
assessment: automated
tags: [services, cups, printing, attack-surface]

description: |
  CUPS is started by `cups.service`, `cups.socket` and `cups.path`; `cups-browsed.service`
  discovers network printers and adds them automatically.

  The control passes when each unit is masked or not installed at all.
rationale: |
  The print stack parses complex documents and network announcements. Flaws in `cups-browsed`
  have allowed remote code execution by announcing a malicious printer. Servers rarely print.
impact: |
  The system can no longer print, and network printers are no longer discovered. Print servers
  and desktops that print keep CUPS: the control is only in the server and hardened desktop
  profiles, and can be excluded in the tailoring file.
notes: |
  The socket and path units can start `cupsd` on their own, so they are masked too.

audit:
  manual: |
    Run `systemctl is-enabled cups.service cups.socket cups.path cups-browsed.service`. Each must
    print `masked`, or fail because the unit does not exist.
  logic: all
  checks:
    - id: cups-browsed
      engine: systemd-unit
      description: Printer discovery daemon.
      spec: { unit: cups-browsed.service, state: masked }
    - id: cups-socket
      engine: systemd-unit
      description: CUPS socket activation.
      spec: { unit: cups.socket, state: masked }
    - id: cups-path
      engine: systemd-unit
      description: CUPS path activation.
      spec: { unit: cups.path, state: masked }
    - id: cups
      engine: systemd-unit
      description: CUPS scheduler.
      spec: { unit: cups.service, state: masked }

remediation:
  manual: |
    Run `systemctl mask --now cups-browsed.service cups.socket cups.path cups.service`, or
    `apt purge cups cups-daemon cups-browsed` if nothing depends on them.
  effects:
    restart: none
    disruption: low
    lockout_risk: false
  rollback: |
    Run `systemctl unmask cups-browsed.service cups.socket cups.path cups.service` then
    `systemctl enable --now cups.service cups-browsed.service`.
  scripts:
    - id: cups-browsed
      from_check: cups-browsed
    - id: cups-socket
      from_check: cups-socket
    - id: cups-path
      from_check: cups-path
    - id: cups
      from_check: cups

references:
  - title: cupsd(8), Debian manual pages
    url: https://manpages.debian.org/trixie/cups-daemon/cupsd.8.en.html
    publisher: Debian
    kind: vendor-doc
    accessed: 2026-10-18
  - title: cups-browsed(8), Debian manual pages
    url: https://manpages.debian.org/trixie/cups-browsed/cups-browsed.8.en.html
    publisher: Debian
    kind: vendor-doc
    accessed: 2026-10-18
  - title: ANSSI-BP-028 v2.0 - Recommandations de configuration d'un système GNU/Linux (R62)
    url: https://messervices.cyber.gouv.fr/documents-guides/fr_np_linux_configuration-v2.0.pdf
    publisher: ANSSI
    kind: guide
    accessed: 2026-10-18
mappings:
  - framework: anssi-linux
    framework_version: "2.0"
    id: R62
    relation: partial
    note: R62 asks to disable every unneeded service and names CUPS; this control covers it.
  - framework: nist-800-53r5
    framework_version: "5.1.1"
    id: CM-7
    relation: partial
  - framework: cis-debian-12
    framework_version: "2.0.0"
    id: "2.1.14"
    relation: equivalent
  - framework: cis-debian-13
    framework_version: "1.1.0"
    id: "2.1.11"
    relation: equivalent
threats:
  - framework: mitre-attack
    id: T1210
  - framework: cwe
    id: CWE-20

authors:
  - name: Alice
    github: Sn0wAlice
verified:
  - date: 2026-10-18
    by: Sn0wAlice
    versions: ["12"]
    environment: Proxmox VM, Debian 12 genericcloud image, kernel 6.1.0-54-cloud-amd64
    notes: "Fresh image passes; with cups and cups-browsed installed the checks fail, fix masks the four units, audit passes after reboot; tested with profiles server-hardened and desktop-hardened."
  - date: 2026-10-18
    by: Sn0wAlice
    versions: ["13"]
    environment: Proxmox VM, Debian 13 genericcloud image, kernel 6.12.113+deb13-cloud-amd64
    notes: "Fresh image passes; with cups and cups-browsed installed the checks fail, fix masks the four units, audit passes after reboot; tested with profiles server-hardened and desktop-hardened."
introduced_in: 0.1.0
created: 2026-10-18
updated: 2026-10-18