# yaml-language-server: $schema=../../../../schema/control.schema.json
id: CB-UBU-SVC-026
title: Disable the kdump kernel crash dump service
finding:
  title: Kernel crash dumps are collected on the system
  description: A crash dump is a copy of memory that can hold keys, passwords and sensitive data.
status: active
profiles: [server-hardened]
risk:
  severity: low
assessment: automated
tags: [services, kdump, kernel, data-exposure]

description: |
  `kdump-tools` loads a capture kernel at boot (`kdump-tools.service`). When the main kernel
  crashes, the capture kernel saves its memory to `/var/crash`.

  The control passes when `kdump-tools.service` is masked or not installed at all.
rationale: |
  The dump holds everything that was in memory: secrets of running services, session keys,
  documents. It stays on disk after the reboot and can be copied by anyone who gets access to
  `/var/crash` or to backups. Kernel crash analysis is rarely needed in production.
impact: |
  Kernel crashes leave no dump to analyse. The memory reserved by the `crashkernel=` boot
  parameter stays reserved until the parameter is removed (`apt purge kdump-tools`, then
  `update-grub` and a reboot).
notes: |
  `kdump-tools` is not installed by default. Systems where kernel developers or support need
  dumps should exclude this control in their tailoring file and protect `/var/crash` instead.

audit:
  manual: |
    Run `systemctl is-enabled kdump-tools.service`. It must print `masked`, or fail because the unit
    does not exist.
  checks:
    - id: kdump-tools
      engine: systemd-unit
      description: kdump capture kernel loader.
      spec: { unit: kdump-tools.service, state: masked }

remediation:
  manual: |
    Run `systemctl mask --now kdump-tools.service`. To also free the reserved memory, run
    `apt purge kdump-tools`, then `update-grub`, and reboot.
  effects:
    restart: none
    disruption: none
    lockout_risk: false
  rollback: |
    Run `systemctl unmask kdump-tools.service` then `systemctl enable --now kdump-tools.service`.
  scripts:
    - id: kdump-tools
      from_check: kdump-tools

references:
  - title: kdump-tools(5), Ubuntu manual pages
    url: https://manpages.ubuntu.com/manpages/noble/man5/kdump-tools.5.html
    publisher: Canonical
    kind: vendor-doc
    accessed: 2026-10-19
  - title: kdump-config(8), Ubuntu manual pages
    url: https://manpages.ubuntu.com/manpages/noble/man8/kdump-config.8.html
    publisher: Canonical
    kind: vendor-doc
    accessed: 2026-10-19
  - 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: 2026-10-19
mappings:
  - framework: anssi-linux
    framework_version: "2.0"
    id: R62
    relation: partial
    note: R62 asks to disable every unneeded service; this control covers kdump.
  - framework: nist-800-53r5
    framework_version: "5.1.1"
    id: CM-7
    relation: partial
threats:
  - framework: mitre-attack
    id: T1003
  - framework: cwe
    id: CWE-528

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
    notes: "Stock image passes (units absent); with kdump-tools installed the check fails, server-hardened remediation masks the units, audit passes, unchanged on a second run and after reboot."
  - date: 2026-10-19
    by: Sn0wAlice
    versions: ["22.04"]
    environment: Proxmox VM, Ubuntu 22.04 cloud image, kernel 5.15.0-198-generic
    notes: "Stock image passes (units absent); with kdump-tools installed the check fails, server-hardened remediation masks the units, audit passes, unchanged on a second run and after reboot."
  - date: 2026-10-19
    by: Sn0wAlice
    versions: ["24.04"]
    environment: Proxmox VM, Ubuntu 24.04 cloud image, kernel 6.8.0-147-generic
    notes: "Stock image passes (units absent); with kdump-tools installed the check fails, server-hardened remediation masks the units, audit passes, unchanged on a second run and after reboot."
  - date: 2026-10-19
    by: Sn0wAlice
    versions: ["26.04"]
    environment: Proxmox VM, Ubuntu 26.04 cloud image, kernel 7.0.0-38-generic
    notes: "Stock image passes (units absent); with kdump-tools installed the check fails, server-hardened remediation masks the units, audit passes, unchanged on a second run and after reboot."
introduced_in: 0.1.0
created: 2026-10-19
updated: 2026-10-19