# yaml-language-server: $schema=../../../../schema/control.schema.json
id: CB-DEB-AUDIT-032
title: Install the AIDE file integrity checker
finding:
  title: No file integrity checker is installed
  description: Changes to system binaries and configuration files, such as a replaced program or a planted backdoor, go unnoticed.
status: active
profiles: [core]
risk:
  severity: medium
assessment: automated
tags: [aide, integrity]

description: |
  AIDE (Advanced Intrusion Detection Environment) records the checksums and attributes of
  system files in a database, then compares the files with it. Debian splits it into `aide`
  (the program) and `aide-common` (configuration in `/etc/aide/`, `aideinit`, daily check).
  Neither is installed by default.
rationale: |
  An integrity checker is the simplest way to detect that files which should never change
  (binaries, libraries, configuration) have been modified, whether by an intruder or by mistake.
impact: |
  Installing AIDE alone does nothing until its database is built (CB-DEB-AUDIT-034).
notes: |
  The fix installs without recommended packages: `aide` recommends a mail transport agent, which
  `apt-get` would otherwise install (exim4). Reports of the daily check are written to
  `/var/log/aide/`; install and configure a mail transport if they must be mailed.

setting:
  location: aide and aide-common packages
  default_value: Not installed
  recommended_value: Installed

audit:
  manual: |
    Run `dpkg-query -W -f='${Package} ${Status}\n' aide aide-common`. Both must end with `installed`.
  checks:
    - id: aide
      engine: package
      description: aide is installed.
      spec: { name: aide, state: installed }
    - id: aide-common
      engine: package
      description: aide-common is installed.
      spec: { name: aide-common, state: installed }

remediation:
  manual: |
    Run `apt-get install --no-install-recommends aide aide-common`.
  effects:
    restart: none
    disruption: none
    lockout_risk: false
  rollback: |
    Run `apt-get purge aide aide-common`.
  scripts:
    - id: install
      engine: shell
      content: |
        DEBIAN_FRONTEND=noninteractive apt-get install -y -q --no-install-recommends aide aide-common

references:
  - title: aide(1), Debian manual pages
    url: https://manpages.debian.org/trixie/aide/aide.1.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: partial
    note: R76 asks to seal files and check them; this control installs the tool, CB-DEB-AUDIT-034 builds and checks the seals.
  - framework: nist-800-53r5
    framework_version: "5.1.1"
    id: SI-7
    relation: related
  - framework: cis-debian-12
    framework_version: "2.0.0"
    id: "6.3.1"
    relation: partial
    note: The database initialisation is in CB-DEB-AUDIT-034.
  - framework: cis-debian-13
    framework_version: "1.1.0"
    id: "6.3.1"
    relation: partial
    note: The database initialisation is in CB-DEB-AUDIT-034.
threats:
  - framework: mitre-attack
    id: T1036.005
  - framework: cwe
    id: CWE-353
related_controls:
  - id: CB-DEB-AUDIT-034
    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; fix installs aide and aide-common without recommends (no MTA pulled); kept after reboot."
  - 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; fix installs aide and aide-common without recommends (no MTA pulled); kept after reboot."
introduced_in: 0.1.0
created: 2026-10-18
updated: 2026-10-18