# yaml-language-server: $schema=../../../../schema/control.schema.json
id: CB-DEB-AUDIT-034
title: Build the AIDE database and check file integrity every day
finding:
  title: File integrity is never checked
  description: Without a reference database and a regular check, AIDE cannot report modified system files.
status: active
profiles: [core]
risk:
  severity: medium
assessment: automated
tags: [aide, integrity, systemd]

description: |
  AIDE needs a reference database, `/var/lib/aide/aide.db`, built with `aideinit` from the
  current state of the system. `aide-common` then ships `dailyaidecheck.timer`, which compares the
  files with the database once a day and writes a report to `/var/log/aide/` (and mails it when a
  mail transport is installed).

  This control requires the database to exist and the timer to be enabled.
rationale: |
  The database is the trusted reference; the daily check turns it into detection. Without either,
  an installed AIDE gives a false sense of protection.
impact: |
  Building the database reads every covered file: a few minutes and a short burst of disk
  activity. The daily check does the same. After legitimate changes (upgrades, configuration),
  review the report and update the database (`aide --update`, then replace `aide.db` with
  `aide.db.new`).
notes: |
  Build the database once the system is in its intended state: run this fix after the other
  hardening fixes, or rebuild the database afterwards with `aideinit -y -f`, otherwise the first
  reports list every change made by the hardening.

setting:
  location: /var/lib/aide/aide.db, dailyaidecheck.timer
  default_value: No database; timer enabled when aide-common is installed
  recommended_value: Database present, timer enabled

audit:
  manual: |
    1. Run `ls -l /var/lib/aide/aide.db`. The file must exist and not be empty.
    2. Run `systemctl is-enabled dailyaidecheck.timer`. It must print `enabled`.
    3. Read the last report in `/var/log/aide/` and check that differences are explained.
  checks:
    - id: database
      engine: shell
      description: The AIDE reference database exists.
      spec:
        script: |
          if [ -s /var/lib/aide/aide.db ]; then
            ls -l /var/lib/aide/aide.db
          else
            echo "/var/lib/aide/aide.db missing or empty"
            exit 1
          fi
    - id: timer
      engine: systemd-unit
      description: dailyaidecheck.timer is enabled.
      spec: { unit: dailyaidecheck.timer, state: enabled }

remediation:
  manual: |
    1. Run `aideinit -y -f` and wait for it to finish (a few minutes).
    2. Run `systemctl enable --now dailyaidecheck.timer`.
  effects:
    restart: none
    disruption: low
    lockout_risk: false
  rollback: |
    Run `systemctl disable --now dailyaidecheck.timer` and delete `/var/lib/aide/aide.db`.
  scripts:
    - id: database
      engine: shell
      content: |
        command -v aideinit >/dev/null 2>&1 || { echo "AIDE is not installed" >&2; exit 1; }
        # umask 027: aideinit would otherwise create its logs readable by everyone
        [ -s /var/lib/aide/aide.db ] || (umask 027; aideinit -y -f)
    - id: timer
      from_check: timer

references:
  - title: aideinit(8), Debian manual pages
    url: https://manpages.debian.org/trixie/aide-common/aideinit.8.en.html
    publisher: Debian
    kind: vendor-doc
    accessed: 2026-10-18
  - title: systemd.timer(5), Debian manual pages
    url: https://manpages.debian.org/trixie/systemd/systemd.timer.5.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 (R76)
    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: R76
    relation: equivalent
  - framework: nist-800-53r5
    framework_version: "5.1.1"
    id: SI-7(1)
    relation: related
  - framework: cis-debian-12
    framework_version: "2.0.0"
    id: "6.3.1"
    relation: partial
    note: The package installation is in CB-DEB-AUDIT-032.
  - framework: cis-debian-12
    framework_version: "2.0.0"
    id: "6.3.2"
    relation: equivalent
  - framework: cis-debian-13
    framework_version: "1.1.0"
    id: "6.3.1"
    relation: partial
    note: The package installation is in CB-DEB-AUDIT-032.
  - framework: cis-debian-13
    framework_version: "1.1.0"
    id: "6.3.2"
    relation: equivalent
threats:
  - framework: mitre-attack
    id: T1036.005
  - framework: cwe
    id: CWE-353
related_controls:
  - id: CB-DEB-AUDIT-032
    type: requires
  - id: CB-DEB-AUDIT-033
    type: requires
  - id: CB-DEB-AUDIT-035
    type: related

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, BIOS boot
    notes: "Fails on fresh install; aideinit builds the database in about 2 minutes on 1 GB RAM; dailyaidecheck.timer enabled; daily check run by hand writes 0640 logs."
  - date: 2026-10-18
    by: Sn0wAlice
    versions: ["13"]
    environment: Proxmox VM, Debian 13 genericcloud image, kernel 6.12.113+deb13-cloud-amd64, BIOS boot
    notes: "Fails on fresh install; aideinit builds the database in about 2 minutes on 1 GB RAM; dailyaidecheck.timer enabled; daily check run by hand writes 0640 logs."
introduced_in: 0.1.0
created: 2026-10-18
updated: 2026-10-18