# yaml-language-server: $schema=../../../../schema/control.schema.json
id: CB-DEB-AUDIT-008
title: Send system logs to a remote log server
finding:
  title: System logs are only stored on the system that produced them
  description: An intruder with root access can erase the local logs, and a lost disk takes the history with it.
status: active
profiles: [core]
risk:
  severity: medium
assessment: manual
tags: [logging, remote, journald, rsyslog]

description: |
  A copy of the logs must leave the system as they are produced, to a log server or a central
  collection platform the system cannot modify. On Debian, two ways fit the chosen logging system:

  - with the journal alone, `systemd-journal-upload` (package `systemd-journal-remote`) sends the
    journal over HTTPS to a `systemd-journal-remote` server;
  - with rsyslog, an `omfwd` action sends messages over TCP, preferably with TLS
    (CB-DEB-AUDIT-009).
rationale: |
  Remote logs survive the compromise or loss of the system and are the reference when local logs
  have been altered. They also allow correlating events across systems.
impact: |
  Requires a log server and network flows to it. Messages are queued when the server is
  unreachable; size the queue so a long outage does not fill the disk.

audit:
  manual: |
    1. With the journal alone: run `systemctl is-active systemd-journal-upload` and check `URL=` in
       `systemd-analyze cat-config systemd/journal-upload.conf`.
    2. With rsyslog: look for an `action(type="omfwd" target=...)` or `@@host` line with
       `grep -Er 'omfwd|^\s*[^#].*@@?' /etc/rsyslog.conf /etc/rsyslog.d/`.
    3. Confirm on the log server that recent messages from this system have arrived.

remediation:
  manual: |
    1. With the journal alone: install `systemd-journal-remote`, set `URL=https://<server>:19532`
       and the client certificate in `/etc/systemd/journal-upload.conf.d/`, then run
       `systemctl enable --now systemd-journal-upload`.
    2. With rsyslog: add to `/etc/rsyslog.d/60-remote.conf`:
       ```
       *.* action(type="omfwd" target="<server>" port="6514" protocol="tcp"
                  StreamDriver="gtls" StreamDriverMode="1" StreamDriverAuthMode="x509/name"
                  queue.type="LinkedList" queue.filename="fwd" queue.saveOnShutdown="on"
                  action.resumeRetryCount="-1")
       ```
       then run `systemctl restart rsyslog`.
  rollback: |
    Disable `systemd-journal-upload`, or remove the forwarding file and restart rsyslog.

references:
  - title: systemd-journal-upload.service(8), Debian manual pages
    url: https://manpages.debian.org/trixie/systemd-journal-remote/systemd-journal-upload.service.8.en.html
    publisher: Debian
    kind: vendor-doc
    accessed: 2026-10-18
  - title: rsyslog.conf(5), Debian manual pages
    url: https://manpages.debian.org/trixie/rsyslog/rsyslog.conf.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 (R71)
    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: R71
    relation: partial
  - framework: nist-800-53r5
    framework_version: "5.1.1"
    id: AU-9(2)
    relation: related
  - framework: cis-debian-12
    framework_version: "2.0.0"
    id: "6.1.2.5"
    relation: equivalent
    note: Ours also accepts the journal upload path when rsyslog is not used.
  - framework: cis-debian-13
    framework_version: "1.1.0"
    id: "6.1.2.5"
    relation: equivalent
    note: Ours also accepts the journal upload path when rsyslog is not used.
threats:
  - framework: mitre-attack
    id: T1070.002
related_controls:
  - id: CB-DEB-AUDIT-009
    type: related

authors:
  - name: Alice
    github: Sn0wAlice
introduced_in: 0.1.0
created: 2026-10-18
updated: 2026-10-18