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docs(ssp): v0.3 — add the fleet-management plane + July hardening changes

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The SSP (v0.2, 2026-06-27) and annex predated the entire management/enrolment
plane and the July hardening work. Bring both to v0.3 (2026-07-10):

SSP:
- Scope/boundary: on-host fleet-agent now IN scope; server-side manager/broker/
  step-ca/InfluxDB named as connected systems; new host interface (g) = outbound
  mTLS to the management plane. Boot chain gains step 8 (post-switch-root agent).
- Data: management telemetry (operational metadata, mTLS-encrypted, no per-host
  secret); the agent stream is the one non-plaintext transit path.
- §5.2 Protect: agent reuses the TPM identity for mTLS; WebAuthn-passkey admin
  MFA (first human-admin MFA); 3 local SELinux modules; the 2026-07-04 fapolicyd
  overlay watch_fs fix (app-control was inactive on the root until then).
- §5.3 Detect: operational health telemetry signal (distinct from auditd/Wazuh).
- §6 Essential Eight: MFA + admin rows updated (passkeys now enforced on mgmt UI).
- §7: new R-14 (mgmt plane = connected system pending authorisation) + R-15
  (deferred agent actuators = future remote-mutation channel); R-05 MFA clause met.

Annex:
- §2.3 hardening: fapolicyd overlay-effectiveness fix + residual; 3 local SELinux
  allow modules on the MAC row.
- §2.4 auth: agent mTLS on the machine-auth row; MFA row now Implemented for the
  mgmt UI (passkeys), Partial for host SSH.
- §2.5 mgmt: new rows for TPM enrolment lifecycle (broker) and server-authoritative
  management plane. §2.6: operational health-monitoring row. §2.7: mgmt-plane
  segmentation (OPNsense L3, outbound-only). §2.9: agent mTLS, fleet CA (step-ca),
  cert-lifecycle auto-renewal.
- §3 register: R-14, R-15 added; R-05 updated; heatmap + note + 3 new assessor
  notes (scope the mgmt plane, witness fapolicyd deny, confirm actuators inert).
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Audiobuzz
2026-07-10 22:56:34 +00:00
parent 3284a2713b
commit 57fb5c3a3e
2 changed files with 166 additions and 56 deletions
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docs/ssp-annex-a-ism-residual-risk.md
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@@ -9,15 +9,23 @@
> **A&A framework:** ASD *Information Security Manual* (ISM) — engagement target
> **May 2026 release**.
>
> **Annex version:** 0.2 (updated 2026-06-22). v0.2 reflects: STIG hardening
> applied + bench-verified, USBGuard device control enabled, admin `staff_u`
> confinement, audit offload verified, PXE/iPXE boot path added, and **UEFI Secure
> Boot signing verified enforcing on real hardware** (VM HTTP + 820 PXE) — R-13
> reduced from Medium to Low (residual is making signed + SB-on the standing
> default); and (2026-06-27) a **Wazuh SIEM** (dedicated multi-node, agentless)
> now decodes + alerts on the fleet auditd stream — "event log analysis/alerting"
> moves Planned → Implemented, R-07 reduced toward Low (residual = TLS transport +
> retention).
> **Annex version:** 0.3 (updated 2026-07-10). v0.3 adds the **fleet-management
> plane**: the in-image **`fleet-agent`** (health telemetry over TPM-mTLS —
> bench-verified on hardware 2026-07-10; new host interface (g)), the server-side
> manager with **WebAuthn-passkey admin MFA** (first human-admin MFA — updates the
> §2.4 MFA row and R-05), the **TPM enrolment broker** + **step-ca fleet CA**, and
> InfluxDB health telemetry. It also records the **three local SELinux policy
> modules** (§2.3) and the **fapolicyd overlay exec-guard fix (2026-07-04)** that
> made application control actually effective on the root. New residual risks
> **R-14** (management plane = connected system, not yet separately authorised) and
> **R-15** (deferred agent actuators = future remote-mutation channel). The
> server-side plane is a **connected system** carrying its own authorisation.
>
> v0.2 (2026-06-22/27) reflected: STIG hardening applied + bench-verified, USBGuard
> device control, admin `staff_u` confinement, audit offload verified, PXE/iPXE
> boot path, **UEFI Secure Boot signing verified enforcing on real hardware** (R-13
> Medium→Low), and a **Wazuh SIEM** (agentless) decoding + alerting on the auditd
> stream (R-07 reduced toward Low).
---
@@ -85,13 +93,13 @@ ISM/PSPF style). Ratings are **pre-treatment** unless stated; the AO accepts the
| Topic | ISM (rep.) | Requirement intent | System implementation | Status | Residual |
|---|---|---|---|---|---|
| Hardened OS to ASD/vendor guidance | ISM-1407*, ISM-1408* | Apply a recognised hardening baseline. | **DISA STIG** (SSG `profile_stig`, RHEL 9) via `oscap --remediate` + documented tailoring + per-build deviations report ([stig-deviations.md](stig-deviations.md)); **applied + bench-verified 2026-06-20**, all REVIEW rows triaged. | Partial | R-03 (CI must ship `enable_stig=true` + signed/SB-on) |
| Application control / allow-listing | ISM-0843*, ISM-1490*, ISM-1657* | Only approved executables run. | **fapolicyd** (RPM-trust + two trusted local binaries: kiosk-session, fleet-sb-enroll) + immutable dm-verity root. | Implemented | — |
| Application control / allow-listing | ISM-0843*, ISM-1490*, ISM-1657* | Only approved executables run. | **fapolicyd** (RPM-trust + trusted local binaries: kiosk-session, fleet-sb-enroll, fleet-agent) + immutable dm-verity root. **Effectiveness fix 2026-07-04:** the diskless root is `overlayfs`, which was missing from fapolicyd's `watch_fs` → the guard was **inactive on the root**; adding `overlay` turned allow-listing on for the whole root (verified: novel `/tmp` binary denied). | Implemented | R (residual): path-trust doesn't catch a *modified trusted path* via copy-up — TODO #15 (`integrity=sha256` option); see [stig-deviations #15](stig-deviations.md) |
| Device / removable-media control | ISM-0341*, ISM-1551* | Control USB / peripheral devices. | **USBGuard enforcing** (`ImplicitPolicyTarget=block` + hardware-independent HID/hub allowlist + LinuxAudit). Verified: USB mass storage blocked, console input preserved. | Implemented | — |
| Software / OS integrity | ISM-1493* | Detect unauthorised modification. | **dm-verity** continuous block-level verification of the read-only root against a signed hash; **reproducible** build. | Implemented | — |
| Disable unneeded functionality | ISM-0380*, ISM-1416* | Minimise installed software/services. | `@^minimal` install; scanner tooling removed post-scan; FROM-scratch artifact image; kiosk = single app. | Implemented | — |
| Hardened user applications (browser) | ISM-1486*, ISM-1412* | Lock down high-risk apps. | Chromium enterprise lockdown policy; weston kiosk; no shell/nav/plugins. | Implemented | — |
| Memory/exploit mitigations | ISM-1341*, ISM-1342* | Enable platform exploit mitigations. | UKI cmdline: `slub_debug=P`, `page_poison=1`, `init_on_alloc/free=1`, `vsyscall=none`. | Implemented | — |
| Mandatory access control | ISM-1416* | MAC enforced. | **SELinux enforcing**; labels preserved into erofs (asserted at build). | Implemented | — |
| Mandatory access control | ISM-1416* | MAC enforced. | **SELinux enforcing**; labels preserved into erofs (asserted at build). Three **local allow modules** for architecture-specific paths (`chrony_dhcp_dispatcher`, `fapolicyd_tmpfs`, `fleet_agent_chronylog`), each minimal + read/monitoring-only and documented ([stig-deviations #14–16](stig-deviations.md)); **no permissive domains**. | Implemented | — |
| Host-based intrusion prevention / file integrity (AIDE) | ISM-1288* | File integrity monitoring. | **N/A** — superseded by dm-verity (read-only, signed, continuous). | N/A (justified) | — |
| Antivirus / endpoint scanning | ISM-1417* | Malware protection on endpoints. | **N/A/compensated** — immutable verified root + allow-listing means no persistent writable executable surface; overlay is RAM-only, discarded each boot. | N/A (justified) | — |
@@ -99,11 +107,11 @@ ISM/PSPF style). Ratings are **pre-treatment** unless stated; the AO accepts the
| Topic | ISM (rep.) | Requirement intent | System implementation | Status | Residual |
|---|---|---|---|---|---|
| Strong machine authentication | ISM-1546*, ISM-0974* | Mutual, certificate-based auth. | **802.1X EAP-TLS**, client key non-exportable in **TPM** (`0x81000100`), cert in TPM NV. | Partial | R-01 (not bench-verified; disabled in test builds), R-08 (placeholder CA) |
| Strong machine authentication | ISM-1546*, ISM-0974* | Mutual, certificate-based auth. | **802.1X EAP-TLS**, client key non-exportable in **TPM** (`0x81000100`), cert in TPM NV. The **management-plane agent reuses the same TPM identity** for mTLS (`RequireAndVerifyClientCert` to the fleet CA; server keys inventory off the verified cert serial). One non-exportable key = 802.1X + NVMe hostnqn + agent stream. | Partial | R-01 (not bench-verified; disabled in test builds), R-08 (placeholder CA), R-14 (mgmt plane = connected system) |
| Privileged access restricted | ISM-1507*, ISM-0445* | Limit & control admin access. | Single key-only `wheel` admin; root login disabled; admin **confined to `staff_u`** with a sudo `sysadm_r`/`sysadm_t` role/type transition (SELinux context elevates on privilege use). | Partial | R-05 |
| Secure remote administration | ISM-1506*, ISM-1232* | Hardened admin channel. | SSH **key-only**, password & keyboard-interactive off, hardened ciphers/MACs/KEX (STIG crypto policy; ECDSA/RSA keys — ed25519 excluded by policy). | Implemented | — |
| No default/shared credentials | ISM-1304* | No baked credentials. | No per-host secrets in any artifact; identity from TPM at runtime; `machine-id` empty; host keys regenerated at first boot. | Implemented | — |
| MFA for privileged users | ISM-1173*, ISM-1504* | MFA on privileged access. | Machine auth is cert+TPM (strong). **Human admin MFA on the management plane not yet enforced.** | Partial | R-05 |
| MFA for privileged users | ISM-1173*, ISM-1504* | MFA on privileged access. | Machine auth is cert+TPM (strong). **Human admin MFA on the management-plane UI now enforced via WebAuthn passkeys** (phishing-resistant, origin-bound, hardware-backed — the manager's admin plane, v0.3). Host **SSH** admin remains key-only (no separate human MFA). | Partial (host SSH) / Implemented (mgmt UI) | R-05 |
| Passwordless appliance accounts | — (STIG #10) | Account lockout/aging. | `kiosk`/`fleetadmin` are key-only; password aging/faillock **exempted for these two only**, full policy system-wide otherwise. | Implemented | R-05 (folds into rotatable-access roadmap) |
### 2.5 Guidelines for System Management
@@ -115,6 +123,8 @@ ISM/PSPF style). Ratings are **pre-treatment** unless stated; the AO accepts the
| Protect build/signing key material | ISM-0501*, ISM-1233* | Protect keys. | Signing keys CI/HSM-held; **never** in repo or build VM; never logged. | Implemented | — |
| Privileged actions logged | ISM-1509* | Admin actions auditable. | auditd rules capture privileged/admin events. | Implemented | R-07 (offload protection) |
| Disable debug/back-door access | ISM-1491* | No undocumented access paths. | `debug_shell=true` currently bakes a **passwordless root tty** (lab debugging). | Partial | **R-02 (must remove before prod)** |
| Device enrolment & identity lifecycle | ISM-1195*, ISM-0475* | Controlled device onboarding. | **TPM enrolment broker** (v0.3): the host generates a key in-TPM, submits a CSR to the one *unauthenticated pre-auth* endpoint; an admin verifies an **OOB fingerprint** and **approves over mTLS**, then **step-ca** signs the leaf into TPM NV and the manager births the inventory record (cert-serial = key). No auto-approval; identity is human-anchored. Server-side = connected system. | Partial (connected system) | R-14 |
| Server-authoritative management plane | ISM-1483*, ISM-1509* | Controlled remote management. | `fleet-agent` streams telemetry + receives desired-state over mTLS; **v1 logs commands but does not act** (no host mutation). Inventory/desired-state is server-authoritative. Reconcile actuators deferred. | Partial | R-14, **R-15 (actuators = future remote-mutation channel)** |
### 2.6 Guidelines for System Monitoring (event logging)
@@ -125,13 +135,14 @@ ISM/PSPF style). Ratings are **pre-treatment** unless stated; the AO accepts the
| Protect logs in transit | ISM-1432*, ISM-0407* | Encrypt/authenticate log transport. | **Plaintext** on both hops (host→collector, collector→Wazuh across a routed mgmt LAN); rsyslog TLS rules waived (see [STIG #6](stig-deviations.md)). | Waived (lab) | **R-07** |
| Log retention & integrity | ISM-0859*, ISM-1815* | Retain & protect logs. | Per-source-host files on collector; Wazuh indexer available for retention/ISM but **archival/retention policy not yet configured**. | Planned | R-07 |
| Event log analysis / alerting | ISM-0109*, ISM-1228* | Review logs; alert on incidents. | **Wazuh SIEM** with a custom **`fleet-auditd`** decoder + severity-tiered rules (`fleet_audit` group; auth, privilege/`USER_CMD`, SELinux). **Decode + alert bench-verified 2026-06-27** (`wazuh-logtest` + live `sudo` in the dashboard). Detection content to expand. | Implemented (content to mature) | R-07 |
| Operational health monitoring | ISM-1228*, ISM-1526* | Monitor system health/availability. | **fleet-agent → fleet-manager** health telemetry over mTLS (v0.3): resource pressure, NVMe-root/auth/**SELinux state**/chrony/kiosk, uptime → InfluxDB time-series + admin dashboard flags (version-drift, **SELinux-permissive**, reboot-pending). Complements the auditd/Wazuh security-event path (operational, not security-event, data). Store/dashboard = connected system; host side = read-only probe + mTLS stream. | Partial (connected system) | R-14 |
### 2.7 Guidelines for Networking
| Topic | ISM (rep.) | Requirement intent | System implementation | Status | Residual |
|---|---|---|---|---|---|
| Network access control (802.1X) | ISM-0520*, ISM-1182* | Authenticate devices to the network. | **802.1X** port-based control; unauthenticated port = no access. | Partial | R-01 |
| Network segmentation | ISM-1181*, ISM-1532* | Segregate & control traffic. | VLAN assignment post-auth; isolated boot LAN; serving stack separated. | Partial | R-09 |
| Network segmentation | ISM-1181*, ISM-1532* | Segregate & control traffic. | VLAN assignment post-auth; isolated boot LAN; serving stack separated. **Management plane (v0.3):** the agent reaches the manager on `:9600` **only via an OPNsense L3 rule** (authenticated host VLAN → `:9600`; never the boot LAN); the admin UI (`:443`, passkey) is on the management network only; enrolment/boot/NVMe/NTP stay on the boot LAN. Agent is **outbound-only** (no inbound host port). | Partial | R-09, R-14 |
| Host-based firewall | ISM-1416*, ISM-1416a* | Restrict host network exposure. | **firewalld disabled** (risk to NVMe/TCP & NM during bring-up). | Waived (lab) | **R-09** |
| Disable unused network functionality | ISM-1296* | Minimise network services. | Minimal services; no extraneous listeners; kiosk has no inbound. | Implemented | — |
@@ -146,8 +157,9 @@ ISM/PSPF style). Ratings are **pre-treatment** unless stated; the AO accepts the
| Topic | ISM (rep.) | Requirement intent | System implementation | Status | Residual |
|---|---|---|---|---|---|
| ASD-Approved Cryptographic Algorithms (AACA) | ISM-0471*, ISM-1446* | Use approved algorithms. | STIG crypto policy (modern ciphers/MACs/KEX); EAP-TLS, MACsec-GCM. **Conformance to ISM AACA not formally asserted; FIPS off.** | Partial | **R-06** |
| ASD-Approved Cryptographic Protocols (AACP) | ISM-1139*, ISM-1453* | Use approved protocols (TLS 1.2+/1.3). | EAP-TLS, NVMe/TCP & log transport currently plaintext on LAN. | Partial | R-04, R-06, R-07 |
| Key protection / non-exportability | ISM-0501*, ISM-1091* | Protect keys in hardware where feasible. | EAP-TLS private key **non-exportable in TPM**; UKI signing keys in HSM/CI. | Implemented | — |
| ASD-Approved Cryptographic Protocols (AACP) | ISM-1139*, ISM-1453* | Use approved protocols (TLS 1.2+/1.3). | EAP-TLS; **management-plane agent stream is mTLS 1.2+** (fleet CA) — encrypted, unlike NVMe/TCP & log transport which remain plaintext on the LAN. | Partial | R-04, R-06, R-07 |
| Key protection / non-exportability | ISM-0501*, ISM-1091* | Protect keys in hardware where feasible. | EAP-TLS **and management-plane** private key **non-exportable in TPM** (one key, three uses); UKI signing keys in HSM/CI. The **fleet CA (step-ca)** that signs host/agent certs is a **connected-system** trust anchor — its key protection is assessed there. | Implemented (host) / R-14 (CA) | R-14 |
| Certificate lifecycle | ISM-1091*, ISM-0501* | Managed cert issuance/renewal. | Host identity cert minted at enrolment (step-ca, into TPM NV). The manager's **agent-plane server cert auto-renews** from the co-located CA (`step ca renew --daemon` + in-process hot-reload) — preserves SANs, no 90-day lapse. Server-side = connected system. | Partial (connected system) | R-14 |
| Cryptographic equipment / module evaluation | ISM-0467*, ISM-1277* | Use evaluated crypto modules. | TPM 2.0 hardware; module-evaluation status to confirm; FIPS module not enabled. | Partial | R-06 |
### 2.10 Guidelines for ICT Equipment & Media
@@ -178,7 +190,7 @@ asked to accept. Treatments map to [docs/TODO.md](TODO.md) (working POA&M).
| **R-02** | `debug_shell=true` bakes a **passwordless root shell** on a tty — an undocumented privileged access path. | 2.5 (ISM-1491*) | Possible × Severe → **High** | Lab-only; physical access required; isolated environment. | Set `debug_shell=false` for all non-lab builds; assert absent in CI. | **Low** | Platform team — *before production* |
| **R-03** | STIG hardening **applied + bench-verified** (2026-06-20, all REVIEW rows triaged); residual is ensuring **CI ships `enable_stig=true`** for production builds (it was toggled off during bring-up). | 2.3 (ISM-1407*/1408*) | Possible × Moderate → **Medium** | Tailoring + register + per-build report; SELinux/fapolicyd/USBGuard on; verified on a real hardened build. | Confirm `ENABLE_STIG="true"` in CI; keep the 0-eval guard; re-run the deviations report on the assessed build. | **Low** | Platform team — *before assessment* |
| **R-04** | NVMe/TCP **root traffic plaintext** on the LAN — exposure of OS content / injection if the segment is compromised. | 2.9 (ISM-1139*/1453*) | Unlikely × Major → **Medium** | Isolated boot LAN; MACsec on the access link (once R-01 done) protects the first hop; dm-verity makes injected root blocks fail verification (integrity preserved even if confidentiality isn't). | Production: TLS/IPsec for the storage transport, or rely on MACsec end-to-end across the fabric; document the decision. | **Low–Medium** | Platform/network — *production* |
| **R-05** | **NOPASSWD key-only admin**; no per-host or rotatable access model; human admin MFA on the mgmt plane not enforced. | 2.4 (ISM-1507*/1173*) | Possible × Moderate → **Medium** | Single fleet-generic admin, key-only, root disabled, ECDSA/RSA key, **now SELinux-confined to `staff_u`** with sudo role/type elevation, fully audited; no interactive password to attack. | Per-host/rotatable access (SSH CA / config-agent) + admin MFA on the management plane. | **Low–Medium** | Platform team — *roadmap* |
| **R-05** | **NOPASSWD key-only host admin**; no per-host or rotatable access model. (Management-plane admin MFA is now **enforced** via WebAuthn passkeys — v0.3; residual is the *host SSH* access model.) | 2.4 (ISM-1507*/1173*) | Possible × Moderate → **Medium** | Single fleet-generic admin, key-only, root disabled, ECDSA/RSA key, **SELinux-confined to `staff_u`** with sudo role/type elevation, fully audited; no interactive password to attack. Mgmt-plane admin actions now behind a phishing-resistant passkey. | Per-host/rotatable **host** access (SSH CA / config-agent); the mgmt-plane MFA clause is now met. | **Low–Medium** | Platform team — *roadmap* |
| **R-06** | **FIPS off**; ISM **AACA/AACP conformance not formally asserted**; crypto-module evaluation status unconfirmed. | 2.9 (ISM-0471*/1139*/1277*) | Possible × Major → **Medium** | Modern STIG crypto policy; non-exportable TPM key; no deliberately weak algorithms. Acceptable at OFFICIAL; **mandatory to resolve for PROTECTED+.** | Assert AACA/AACP conformance; decide on FIPS module / evaluated crypto alongside Secure Boot signing. | **Low** (at appropriate classification) | Security + Platform — *before PROTECTED+* |
| **R-07** | Audit-log **offload plaintext** on both hops (host→collector, collector→Wazuh) and **log retention/archival not yet configured** — logs interceptable in transit and retention/tamper-protection undefined. (**SIEM analysis + alerting now in place** — Wazuh, decode+alert bench-verified 2026-06-27; transport bench-verified 2026-06-20.) | 2.6 (ISM-1432*/0109*/0859*) | Possible × Moderate → **Low–Medium** | Isolated/mgmt LAN; disk-assisted queue (no loss on collector/SIEM blip); auditd local copy; per-source files; **Wazuh now actively decodes + alerts** (`fleet_audit`). | rsyslog **TLS** (gtls/6514) on both hops + bundle CA in image (re-select the 3 waived `rsyslog_encrypt_offload_*` rules); configure Wazuh **retention/archival** (ISM) + rotate default creds + restrict dashboard/API. | **Low** | Platform/SecOps — *production* |
| **R-13** | **Boot-chain signing not yet the standing default** — signing + Secure Boot enforcement are **verified end-to-end on real hardware** (VM HTTP UKI 2026-06-20; 820 PXE signed iPXE→UKI 2026-06-22, SB enforcing, `db` enrolled), but unsigned/SB-OFF lab builds remain possible (CI signs only when `SB_KEY`/`SB_CERT` are set) and not every host has `db` enrolled, so a substituted artifact could still boot on an un-enrolled/unsigned host. | 2.10 (ISM-1542*/0312*) | Unlikely × Major → **Low** | Capability **proven on hardware**; dm-verity rejects a tampered *root* regardless; isolated lab LAN. | Make signed + Secure-Boot-on the **default for all production builds/hosts**: keep `SB_KEY`/`SB_CERT` CI secrets set; enrol `db` fleet-wide; treat an unsigned build as lab-only. | **Low** | Platform team — *before production* |
@@ -187,19 +199,21 @@ asked to accept. Treatments map to [docs/TODO.md](TODO.md) (working POA&M).
| **R-10** | **Patch SLA undefined** — no documented cadence for rebuilding/redeploying against new CVEs. | 2.5 (ISM-1144*/1472*) | Likely × Moderate → **Medium** | Atomic rebuild/redeploy model makes patching fast & uniform; reproducible builds. | Define patch cadence & critical-CVE SLA; automate rebuild triggers. | **Low** | Platform team — *roadmap* |
| **R-11** | **No remote attestation** of TPM boot measurements — a compromised boot can't be detected centrally. | 2.10 (ISM-1542*) | Unlikely × Major → **Low–Medium** | Secure Boot + signed UKI + dm-verity already prevent unsigned/modified boot; measurements exist locally. | Implement remote attestation (TPM quote → verifier) gating network/storage access. | **Low** | Platform team — *roadmap* |
| **R-12** | **No formal Incident Response Plan**; volatile RAM overlay complicates live forensics. | 2.1, 2.6 (ISM-0043*/0109*) | Possible × Moderate → **Medium** | Inherent recovery (reboot → verified state; revert digest); centralised logs survive host wipe. | Author IRP + log-retention + break-glass/forensics procedure suited to stateless hosts. | **Low** | SecOps — *before production* |
| **R-14** | **Management/enrolment plane is a connected system, built but not yet separately authorised.** The host now trusts + streams to the fleet-manager and enrols via the broker + **step-ca fleet CA** (a new trust anchor + key material); the broker exposes **one unauthenticated pre-auth CSR endpoint**; InfluxDB holds telemetry + a bearer token. These server-side controls (CA key protection, broker hardening, admin-plane exposure, data-at-rest) are outside this SSP's boundary. | 2.4, 2.5, 2.6, 2.9 (ISM-1546*/1483*/0501*) | Possible × Moderate → **Medium** | Host-side exposure is limited: **outbound-only** mTLS, TPM-bound identity, **read-only** telemetry (no user data), and **commands logged-not-applied in v1**. Broker enrolment is human-anchored (OOB fingerprint + admin mTLS approve; no auto-approval). Mgmt-plane admin UI behind passkey MFA. | Author a **separate SSP/authorisation** for the management plane (CA key protection, broker endpoint hardening + rate-limiting, InfluxDB token/data protection, admin-plane network exposure); TLS everywhere is already in place on this plane. | **Low–Medium** | Platform/SecOps — *before the mgmt plane is production* |
| **R-15** | **Deferred agent reconcile actuators.** v1 receives `DesiredState`/`Command` but **only logs** them; when actuation (apply `kiosk_url` / `reboot` / drain) is built, `fleet-agent` becomes a **remote host-mutation channel**. | 2.5 (ISM-1483*/1509*) | Rare × Moderate → **Low** (v1) | v1 performs **no host mutation** — the receive path is inert; the command authZ path (server-authoritative desired-state, verified over mTLS) is designed but not exercised. | At build time, assess the command/authZ path (who can set desired-state, replay/authZ, blast radius of `reboot`/drain) before enabling actuators; keep it behind an explicit flag. | **Low** | Platform team — *at actuator build* |
### 3.1 Risk heatmap (post-treatment targets)
```
Consequence → Minor Moderate Major Severe
Consequence → Minor Moderate Major Severe
Likelihood ↓
Certain
Likely R-10 R-01*
Possible R-05 R-07 R-03 R-02*
R-12 R-06 R-08
Unlikely R-04
R-11 R-09
Rare
Certain
Likely R-10 R-01*
Possible R-05 R-07 R-03 R-02*
R-12 R-14 R-06 R-08
Unlikely R-04
R-11 R-09
Rare R-15
( * = currently High pre-treatment; all targeted to Low after treatment )
```
@@ -208,10 +222,14 @@ Low–Medium. The AO is asked to authorise on the basis that **R-01, R-02, R-08,
R-12 and R-13** (and confirming R-03's `enable_stig=true`) are **closed before
production**, and R-04/R-05/R-06/R-07/R-09/R-10/R-11 are either accepted with
compensating controls (isolated-LAN lab) or carried on the POA&M with target
dates. Newly strengthened in v0.2: device control (USBGuard, now Implemented),
admin SELinux confinement (R-05), STIG applied+verified (R-03 reduced), and
**Secure Boot signing verified enforcing on real hardware (R-13 reduced
Medium→Low)**.*
dates. Newly recorded in v0.3: **R-14** (the management/enrolment plane is a
connected system requiring its own authorisation) and **R-15** (deferred agent
actuators — a future remote-mutation channel, inert in v1). Newly *strengthened*
in v0.3: **human-admin MFA on the management plane** via WebAuthn passkeys
(improves R-05's MFA clause), and **application control made effective on the
overlay root** (the 2026-07-04 fapolicyd `watch_fs` fix). Carried from v0.2:
USBGuard device control, admin SELinux confinement, STIG applied+verified, and
Secure Boot signing verified enforcing on real hardware (R-13 Medium→Low).*
---
@@ -238,6 +256,18 @@ Medium→Low)**.*
PXE/iPXE SB-OFF cmdline workaround is a no-op once SB is on.
8. **Witness device control** (USBGuard): a USB mass-storage device is blocked and
logged, console HID still works.
9. **Scope the management plane (R-14).** Confirm whether the server-side
fleet-manager / enrol-broker / step-ca / InfluxDB are assessed under a **separate
authorisation**, and that the host↔plane boundary (outbound-only mTLS, TPM
identity, telemetry-only v1) is as described. Witness: an agent mTLS session is
rejected for a serial not in inventory; the broker will not sign without the OOB
fingerprint + admin-mTLS approval; the admin UI requires a passkey.
10. **Confirm application control is effective on the root** (post-2026-07-04 fix):
on an enforcing build, a **novel non-RPM binary in `/tmp` is denied** (fapolicyd
`FAN_DENY`) — proving the `overlay` `watch_fs` entry took (earlier builds silently
did not guard the overlay root).
11. **Confirm actuators are inert (R-15):** the assessed build's `fleet-agent`
**logs but does not apply** desired-state/commands (telemetry-only v1).
---
docs/ssp.md
+107 -27
View File
@@ -15,11 +15,11 @@
|---|---|
| System name | Diskless Fleet Boot System ("the fleet") |
| Document type | System Security Plan (SSP) |
| Version | 0.2 (DRAFT — pre-assessment) |
| Date | 2026-06-27 |
| Version | 0.3 (DRAFT — pre-assessment) |
| Date | 2026-07-10 |
| Author / maintainer | System Owner (delegate) |
| Status | Lab / pre-production. STIG hardening applied + bench-verified; **UEFI Secure Boot signing verified enforcing on real hardware** (VM HTTP + EliteBook 820 PXE); secure path (802.1X/MACsec) not yet bench-verified. |
| Companion documents | [Annex A — ISM control cross-reference & residual risk](ssp-annex-a-ism-residual-risk.md); [Architecture design v2](diskless-fleet-design-v2.pdf); [Design errata](design-v2-errata.md); [STIG deviation register](stig-deviations.md); [Backlog / POA&M source](TODO.md) |
| Status | Lab / pre-production. STIG hardening applied + bench-verified; **UEFI Secure Boot signing verified enforcing on real hardware** (VM HTTP + EliteBook 820 PXE); secure path (802.1X/MACsec) not yet bench-verified. **v0.3 adds the fleet-management plane** (on-host `fleet-agent` telemetry over TPM-mTLS — bench-verified on hardware 2026-07-10; server-side manager with **WebAuthn-passkey** admin MFA + TPM enrolment broker) and July hardening changes (three local SELinux modules; fapolicyd overlay exec-guard fix). |
| Companion documents | [Annex A — ISM control cross-reference & residual risk](ssp-annex-a-ism-residual-risk.md); [Architecture design v2](diskless-fleet-design-v2.pdf); [Design errata](design-v2-errata.md); [Fleet-management design](fleet-management-design.md); [TPM enrolment design](tpm-enrolment-design.md); [STIG deviation register](stig-deviations.md); [Backlog / POA&M source](TODO.md) |
> **Currency caveat (read before relying on control numbers).** This SSP and its
> annex are drafted against the ISM structure as understood to a January 2026
@@ -45,14 +45,20 @@ decision.
**In scope:** the boot chain (UEFI HTTP boot → signed UKI → dracut initramfs →
network authentication → encrypted root mount → verified read-only OS), the
runtime workstation OS image, the host's cryptographic identity (TPM), and the
hardening baseline applied to the image.
runtime workstation OS image, the host's cryptographic identity (TPM), the
hardening baseline applied to the image, and the **on-host `fleet-agent`** (the
in-image telemetry client that streams host health to the management plane over
TPM-mTLS — new in v0.3; `files/agent/`).
**Out of scope (separately authorised):** the lab serving stack (DHCP/HTTP/
NVMe-oF target, audit collector — `serving/`), the 802.1X authenticator/RADIUS
infrastructure, the certificate enrolment authority, the network fabric, and
physical security of the facility. These are dependencies referenced here but
carry their own security documentation and authorisation.
**Out of scope (separately authorised — connected systems):** the lab serving
stack (DHCP/HTTP/NVMe-oF target, audit collector — `serving/`); the **server-side
fleet-management plane** (`serving/fleet-manager/` — the control-plane hub, its
admin web UI, the InfluxDB metrics store, and the Traefik ingress); the **TPM
enrolment broker** (`serving/enrol-broker/`) and the **step-ca fleet certificate
authority** it signs against; the 802.1X authenticator/RADIUS infrastructure; the
network fabric; and physical security of the facility. These are dependencies the
host connects to and are described here where the host interacts with them, but
each carries its own security documentation and authorisation.
## 2. System description
@@ -104,18 +110,28 @@ manifest. One commit = one release = one digest = one manifest entry.
7. `switch-root` into the real system; NetworkManager renews the DHCP lease so
the network-mounted root stays alive; the host derives its NVMe `hostnqn` from
the TPM certificate serial and (kiosk builds) launches the locked-down kiosk.
8. **Post-boot management (v0.3):** the hardened **`fleet-agent`** service dials
the management plane and identifies with the **same TPM key/cert** used for
802.1X and the NVMe `hostnqn` ("one identity, three stages"), streaming host
health over mTLS. It is telemetry-only in v1 — it receives desired-state /
commands but **only logs** them (no host mutation). It is a
**post-switch-root** component only (not in the initramfs).
### 2.3 Authorisation boundary
The authorisation boundary is the **running workstation host**: the UKI, the
initramfs and its custom 802.1X/MACsec dracut module, the verified erofs root,
the tmpfs overlay, the TPM-backed identity, and the hardened OS configuration.
The boundary's external interfaces are: (a) the **access link** (802.1X-controlled
port, MACsec-encrypted); (b) the **NVMe/TCP** root storage session; (c)
**outbound audit log** forwarding; (d) the **kiosk application** endpoint the
browser renders; (e) the **boot transport** (UEFI HTTP boot, or PXE/TFTP→iPXE)
that delivers the UKI; and (f) **USB/peripheral** ports, now mediated by USBGuard
(§5.2). Each crossing is a control point addressed in Annex A.
the tmpfs overlay, the TPM-backed identity, the hardened OS configuration, and the
in-image **`fleet-agent`**. The boundary's external interfaces are: (a) the
**access link** (802.1X-controlled port, MACsec-encrypted); (b) the **NVMe/TCP**
root storage session; (c) **outbound audit log** forwarding; (d) the **kiosk
application** endpoint the browser renders; (e) the **boot transport** (UEFI HTTP
boot, or PXE/TFTP→iPXE) that delivers the UKI; (f) **USB/peripheral** ports, now
mediated by USBGuard (§5.2); and (g) the **management plane** — an *outbound-only*
mTLS gRPC session from `fleet-agent` to the fleet-manager (`manager.fleet.lab:9600`,
across the OPNsense L3 hop from the host VLAN to the management network; no inbound
host port), authenticated with the host's TPM identity cert. Each crossing is a
control point addressed in Annex A.
### 2.4 Data and classification
@@ -127,7 +143,16 @@ that delivers the UKI; and (f) **USB/peripheral** ports, now mediated by USBGuar
CI/HSM-held and **never enter the build VM or the repository**.
- **Data in transit:** access link protected by **MACsec**; NVMe/TCP root and
audit-log offload currently **plaintext on an isolated lab LAN** (see residual
risk R-04, R-07 in Annex A).
risk R-04, R-07 in Annex A). The **management-plane** telemetry stream is
**mTLS-encrypted** (fleet CA) end-to-end — unlike the NVMe/audit hops, it is not
plaintext.
- **Management telemetry (v0.3):** the agent sends host **health** (load/cpu/temp/
memory/tmpfs, uptime, NVMe-root state, 802.1X/MACsec + SELinux state, chrony
clock health, kiosk state) and **inventory facts** (image version, kernel,
cert-serial). This is **operational metadata, not user data**, and it carries **no
per-host secret** (identity is the reused TPM cert; the private key never leaves
the TPM). It is retained server-side (InfluxDB) — a **connected-system**
responsibility (see §1, R-14).
- **Data at rest in the overlay:** ephemeral, RAM-only, discarded at power-off.
The **system's data classification governs this SSP's marking and the required
@@ -164,8 +189,27 @@ This system follows the ISM A&A lifecycle:
Milestones (POA&M)** (this repo's [TODO.md](TODO.md) is the working POA&M
source).
**Current status:** Pre-assessment **DRAFT (v0.2, updated 2026-06-27)**. The system
is functional in a lab configuration. **Progress since v0.1 (2026-06-20):** DISA
**Current status:** Pre-assessment **DRAFT (v0.3, updated 2026-07-10)**. The system
is functional in a lab configuration.
**Progress since v0.2 (2026-07-10):** the **fleet-management plane** was built and,
on the host side, **bench-verified end-to-end on real hardware** (`comet-beacon-54`):
the in-image **`fleet-agent`** streams health to the server over **mTLS using the
reused TPM identity** (telemetry-only — desired-state/commands are received but only
logged, zero host mutation). The server-side manager adds a **WebAuthn-passkey**
(phishing-resistant, origin-bound) admin plane — the first **human-admin MFA** on the
management plane — and a **TPM enrolment broker** (unauthenticated pre-auth CSR → OOB
fingerprint → admin-mTLS approve → step-ca sign) that births the per-host inventory
record. Its server-side server cert now **auto-renews** from the co-located CA. Host
hardening also advanced: **three local SELinux policy modules** were added (all
documented deviations — [stig-deviations.md](stig-deviations.md) #14–16), and a
**material fapolicyd finding was fixed (2026-07-04)** — the app-allow-listing exec
guard was effectively *inactive on the overlay root* (`overlay` missing from
`watch_fs`) and is now enforcing across the whole root (see §5.2). The server-side
plane (manager/broker/InfluxDB/step-ca) is a **connected system** pending its own
authorisation (R-14).
**Progress since v0.1 (2026-06-20):** DISA
STIG hardening applied and **bench-verified** on a real build (kiosk, key-only SSH,
audit offload, DHCP-named host, NVMe/verity root all good with hardening on);
USBGuard device control enabled + verified; admin confined to `staff_u`; **UEFI
@@ -201,7 +245,18 @@ summarises the implementation posture.
### 5.2 Protect
- **Identity & authentication:** mutual **802.1X EAP-TLS** with a
**non-exportable TPM key**; network access controlled at the switch port.
**non-exportable TPM key**; network access controlled at the switch port. The
**management-plane agent reuses the same TPM identity** for mTLS to the
fleet-manager (one non-exportable key backs 802.1X, the NVMe `hostnqn`, and the
agent stream — "one identity, three stages"), and the server keys inventory off
the verified cert serial, so a host can only ever report as itself.
- **Management-plane admin MFA (v0.3):** the server-side admin web UI enforces
**WebAuthn passkeys** — phishing-resistant, origin-bound, hardware-backed
MFA — behind a Traefik ingress that terminates a Let's Encrypt cert (DNS-01).
This is the first human-admin MFA in the system (the manager/broker admin planes
are a **connected system**, but the control is noted here as it closes the
long-standing "no admin MFA" gap for management operations; host SSH admin
remains key-only — R-05).
- **Link protection:** **MACsec** on the access link.
- **Boot & OS integrity:** **Secure Boot** + **signed UKI** with an **immutable
cmdline**; **dm-verity** read-only root (continuous cryptographic integrity);
@@ -221,7 +276,21 @@ summarises the implementation posture.
SSH**, root login disabled, hardened ciphers/MACs/KEX (note: STIG crypto policy
drops ed25519 → admin key must be ECDSA/RSA); **kiosk lockdown** (single locked
browser, no shell/navigation); **postfix removed** (no local MTA — audit-failure
notification rides the remote offload, not email).
notification rides the remote offload, not email). Three **local SELinux policy
modules** are shipped for architecture-specific allows, each a documented
deviation ([stig-deviations.md](stig-deviations.md) #14–16): `chrony_dhcp_dispatcher`
(NM-dispatcher chrony reload), `fapolicyd_tmpfs` (statfs the overlay upper), and
`fleet_agent_chronylog` (agent reads chrony's tracking log). No blanket
permissive domains; SELinux stays enforcing.
- **Application-control effectiveness fix (2026-07-04):** a bench finding showed
fapolicyd's exec guard was **effectively inactive on the root** — the diskless
root is `overlayfs`, which was **absent from fapolicyd's `watch_fs`**, so
fapolicyd marked no mounts and intercepted no exec on `/`, `/usr` or `/tmp`.
Adding `overlay` to `watch_fs` turned app-allow-listing **on for the whole
overlay root for the first time** — verified: a novel non-RPM binary in `/tmp`
is now denied (`FAN_DENY`), nothing legitimate broke. (Residual: path-based trust
doesn't catch a *modified trusted path* via copy-up — tracked as TODO #15 /
the `integrity=sha256` option — noted in stig-deviations #15.)
- **Privileged access:** single **key-only `wheel` admin**, root locked. The admin
is now **confined to the `staff_u` SELinux user** with a sudoers role/type
transition (`sysadm_r`/`sysadm_t`) so privilege elevation re-labels the SELinux
@@ -252,7 +321,16 @@ summarises the implementation posture.
2026-06-27** (`wazuh-logtest` + a live `sudo` surfacing `USER_CMD`/`CRED_*` in
the dashboard). Config is declarative (`serving/siem/`, mounted via
`/wazuh-config-mount`).
- *Gaps:* both offload hops (host→collector, collector→Wazuh) currently
- **Fleet health telemetry (v0.3):** the `fleet-agent` streams host health
(resource pressure, NVMe-root/auth/SELinux/chrony/kiosk state, uptime) to the
manager over mTLS; the manager persists a time-series (InfluxDB) and flags
version-drift, SELinux-permissive, and reboot-pending in an admin dashboard. This
is an **operational-health** signal (complements the auditd/Wazuh **security-event**
path — different purpose, different data): e.g. a host reporting `SELinux:
permissive` or overlay RAM exhaustion is surfaced for the operator. The store and
dashboard are a **connected system** (server-side); the host-side contribution is
the read-only probe + mTLS stream.
- *Gaps:* both audit-offload hops (host→collector, collector→Wazuh) currently
**plaintext** (TLS planned, R-07); **log retention/archival** (ISM) not yet
configured; default Wazuh credentials to be rotated before production.
@@ -275,9 +353,9 @@ AO will expect a maturity view:
| Patch applications | **Process** | Patching = rebuild + re-sign + redeploy a new digest; cadence/SLA to be defined. |
| Configure MS Office macros | **N/A** | No office suite; kiosk is a locked browser. |
| User application hardening | **Strong (kiosk)** | Chromium locked down via enterprise policy; no plugins/shell/nav. |
| Restrict admin privileges | **Partial** | Single key-only `wheel` admin, root locked, now **SELinux-confined to `staff_u`** with a sudo role/type transition (NOPASSWD, see R-05); no per-host/rotatable model or admin-MFA yet. |
| Restrict admin privileges | **Partial** | Single key-only `wheel` admin, root locked, now **SELinux-confined to `staff_u`** with a sudo role/type transition (NOPASSWD, see R-05); **management-plane** admin actions now require a **WebAuthn passkey** (v0.3). Still no per-host/rotatable *host* access model. |
| Patch operating systems | **Process** | Same rebuild/redeploy model; immutable image means uniform, atomic OS updates. |
| Multi-factor authentication | **Strong (machine)** | Host auth is certificate + TPM-bound key (something-the-machine-has, non-exportable). Human admin MFA to be addressed for the management plane. |
| Multi-factor authentication | **Strong (machine) + admin passkey** | Host auth is certificate + TPM-bound key (something-the-machine-has, non-exportable). **Human admin MFA is now enforced on the management-plane UI via WebAuthn passkeys** (phishing-resistant, origin-bound) — v0.3. Host SSH admin remains key-only (no separate human MFA — R-05). |
| Regular backups | **N/A (by design)** | Diskless, stateless hosts hold nothing to back up; recoverability is re-provisioning from a pinned digest. Backup applies to serving-side state, out of scope here. |
## 7. Residual risk summary
@@ -292,12 +370,14 @@ production ATO:
| R-02 | `debug_shell=true` bakes a **passwordless root shell** on a tty. | **High** | Treat — must be removed before production (lab-only). |
| R-03 | STIG hardening **applied + bench-verified** (2026-06-20); residual is that CI ships **unsigned, Secure Boot OFF** and `enable_stig` must be confirmed on for production builds. | **Medium** | Treat — confirm `enable_stig=true` in CI + enforce signing/SB before assessment. |
| R-04 | NVMe/TCP root traffic **plaintext** on the lab LAN. | **Medium** | Accept (isolated LAN) / treat for production. |
| R-05 | NOPASSWD key-only admin (now `staff_u`-confined); no per-host/rotatable access model or admin-MFA. | **Medium** | Accept with compensating controls / roadmap. |
| R-05 | NOPASSWD key-only **host** admin (now `staff_u`-confined); no per-host/rotatable access model. (Management-plane admin MFA now enforced via WebAuthn passkeys — v0.3.) | **Medium** | Accept with compensating controls / roadmap. |
| R-06 | **FIPS off**; ASD-approved-cryptography conformance not yet asserted. | **Medium** | Treat — required for PROTECTED+; revisit with signing. |
| R-07 | Audit-log offload **plaintext** on both hops (host→collector, collector→Wazuh); **log retention not yet configured**. SIEM **analysis + alerting now in place** (Wazuh, decode+alert bench-verified 2026-06-27). | **Low–Medium** | Treat — TLS both hops + ISM retention/archival + rotate Wazuh creds before production. |
| R-08 | **Placeholder RADIUS CA** in the repo; real trust anchor not yet provisioned. | **Medium** | Treat — environment-specific, before production. |
| R-09 | Host **firewall disabled** (workstation). | **Low–Medium** | Accept (isolated LAN) / treat with explicit allow-rules. |
| R-13 | **Boot-chain signing not yet the standing default.** Signing + Secure Boot enforcement **verified end-to-end on hardware** (VM HTTP UKI 2026-06-20; 820 PXE signed iPXE→UKI 2026-06-22), but unsigned/SB-OFF lab builds are still possible (CI signs only when `SB_KEY`/`SB_CERT` are set) and not all hosts have `db` enrolled. | **Low** | Treat — make signed + Secure-Boot-on the default for all production builds/hosts (set CI secrets; enrol `db` fleet-wide). |
| R-14 | **Management/enrolment plane is a connected system, built but not yet separately authorised.** The host now trusts + streams to the fleet-manager and enrols via the broker/**step-ca fleet CA** (a new trust anchor + key material) whose one **unauthenticated pre-auth CSR endpoint** is a new server-side surface. Host-side exposure is limited (outbound-only mTLS, read-only telemetry, commands logged-not-applied in v1). | **Medium** | Treat — separate SSP/authorisation for the management plane (CA key protection, broker endpoint hardening, InfluxDB token/data, admin-plane exposure). |
| R-15 | **Deferred agent reconcile actuators.** v1 receives `DesiredState`/`Command` but only logs them; when actuation (apply kiosk_url / reboot / drain) is built, the agent becomes a **remote host-mutation channel** needing re-assessment. | **Low** (v1) | Treat at build time — assess the command/authZ path before enabling actuators. |
Each is detailed, ISM-cross-referenced, rated and assigned a treatment in Annex A.