{ "id": "CB-UBU-SVC-004", "standard": "ubuntu", "version": "0.1.0", "url": "https://baselines.cirsec.org/b/ubuntu/v0.1.0/CB-UBU-SVC-004", "json": "https://baselines.cirsec.org/b/ubuntu/v0.1.0/CB-UBU-SVC-004.json", "yaml": "https://baselines.cirsec.org/b/ubuntu/v0.1.0/CB-UBU-SVC-004.yml", "profiles_effective": [ "core", "server", "server-hardened", "desktop", "desktop-hardened" ], "license": "Text CC BY 4.0, code Apache-2.0", "attribution": "CIRSEC Baselines, https://baselines.cirsec.org", "control": { "id": "CB-UBU-SVC-004", "title": "Disable LDAP and NIS directory server services the system does not provide", "finding": { "title": "An LDAP or NIS directory server can run on a system that does not provide one", "description": "A forgotten directory server can leak account data or let an attacker publish accounts." }, "status": "active", "profiles": [ "core" ], "risk": { "severity": "medium" }, "assessment": "automated", "tags": [ "services", "ldap", "nis", "attack-surface" ], "description": "Directory servers packaged by Ubuntu:\n\n- OpenLDAP: `slapd`;\n- NIS: `ypserv`, with its companions `yppasswdd` (password changes) and `ypxfrd` (map\n transfers).\n\nThe control passes when each unit is masked or not installed at all.\n", "rationale": "A directory server holds account and group data that other systems trust. NIS sends password\nhashes to any client that asks and has no real authentication; an unattended OpenLDAP server\ncan expose or accept changes to that data.\n", "impact": "Masking a unit stops it and prevents it from starting again. LDAP and NIS clients are not\naffected. Directory servers must exclude this control in their tailoring file.\n", "notes": "A unit that does not exist counts as compliant. On Ubuntu, `slapd` only ships a System V init\nscript; systemd still masks the generated `slapd.service`.\n", "audit": { "manual": "For each unit, run `systemctl is-enabled `. It must print `masked`, or fail because the\nunit does not exist: `slapd.service`, `ypserv.service`, `yppasswdd.service`, `ypxfrd.service`.\n", "logic": "all", "checks": [ { "id": "slapd", "engine": "systemd-unit", "description": "OpenLDAP server.", "spec": { "unit": "slapd.service", "state": "masked" } }, { "id": "ypserv", "engine": "systemd-unit", "description": "NIS server.", "spec": { "unit": "ypserv.service", "state": "masked" } }, { "id": "yppasswdd", "engine": "systemd-unit", "description": "NIS password update server.", "spec": { "unit": "yppasswdd.service", "state": "masked" } }, { "id": "ypxfrd", "engine": "systemd-unit", "description": "NIS map transfer server.", "spec": { "unit": "ypxfrd.service", "state": "masked" } } ] }, "remediation": { "manual": "Stop and mask each unit that is installed: `systemctl mask --now `. If the package is not\nneeded at all, remove it instead: `apt purge slapd ypserv`.\n", "effects": { "restart": "none", "disruption": "low", "lockout_risk": false }, "rollback": "Run `systemctl unmask ` then `systemctl enable --now `.\n", "scripts": [ { "id": "slapd", "from_check": "slapd" }, { "id": "ypserv", "from_check": "ypserv" }, { "id": "yppasswdd", "from_check": "yppasswdd" }, { "id": "ypxfrd", "from_check": "ypxfrd" } ] }, "references": [ { "title": "slapd(8), Ubuntu manual pages", "url": "https://manpages.ubuntu.com/manpages/noble/man8/slapd.8.html", "publisher": "Canonical", "kind": "vendor-doc", "accessed": "2026-10-19" }, { "title": "ypserv(8), Ubuntu manual pages", "url": "https://manpages.ubuntu.com/manpages/noble/man8/ypserv.8.html", "publisher": "Canonical", "kind": "vendor-doc", "accessed": "2026-10-19" }, { "title": "systemctl(1), Ubuntu manual pages", "url": "https://manpages.ubuntu.com/manpages/noble/man1/systemctl.1.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 and names NIS; this control covers directory servers." }, { "framework": "nist-800-53r5", "framework_version": "5.1.1", "id": "CM-7", "relation": "partial" } ], "threats": [ { "framework": "mitre-attack", "id": "T1210" }, { "framework": "mitre-attack", "id": "T1087.002" } ], "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; with slapd and nis installed (SysV units, generated) the checks fail, fix masks them, 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 slapd and nis 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 slapd and nis 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 slapd and nis 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" } }