Tightening Stig hardening

2026-06-20 00:05:19 +00:00
parent b9258e7490
commit b67a23e718
8 changed files with 847 additions and 24 deletions
@@ -171,6 +171,33 @@ instead of working around it.
  nondeterministic (timestamp/uuid/key); find + normalize it in 2d hygiene;
  (d) read the generated `stig-deviations.md` — every REVIEW row is a real finding
  to triage or justify in `docs/stig-deviations.md`.
  **STIG-breaks-login gotchas already hit + fixed (2026-06-19) — don't regress:**
  (i) **fapolicyd** blocks non-RPM executables → the kiosk's
  `/usr/local/bin/kiosk-session` must be in fapolicyd's trust (done in
  2c-STIG-postfix); keep fapolicyd, don't waive it (it's the writable-overlay
  exec guard dm-verity can't provide). (ii) **Admin SSH key must be ECDSA/RSA,
  NOT ed25519** — the STIG crypto policy drops ed25519 from sshd's accepted
  pubkey algorithms (`server-sig-algs` shows ecdsa+rsa-sha2 only), so an ed25519
  key gets `Permission denied (publickey)` at the signature stage. (iii)
  **passwordless/key-only appliance accounts** (kiosk, fleetadmin) are exempted
  from STIG password-aging + faillock account phase in 2c-STIG-postfix (else
  locked out). (iv) the kiosk unit is `WantedBy=multi-user.target` (not
  graphical.target, which the host never reaches → unit dead at boot).
  Offline diagnosis without booting: mount the OCI image's `rootfs.erofs`
  read-only and inspect `/etc/pam.d`, fapolicyd, sshd config, etc.
  **REVIEW-row triage (2026-06-20, scan app-9f7d8d1) added two more bench gates —
  don't regress:** (v) **USBGuard is ENABLED + enforcing** (block target) with a
  hardware-independent HID/hub allowlist + `AuditBackend=LinuxAudit` (2c-STIG). The
  generated policy is built on the virtio build VM (no real USB), so without the
  HID/hub allow rules a **physical console keyboard/mouse is blocked** on real
  hardware — BENCH-VERIFY console input. (vi) **admin sudo SELinux elevation**:
  the admin is mapped to **`staff_u`** (`semanage login`) + sudoers
  `TYPE=sysadm_t ROLE=sysadm_r NOPASSWD:ALL` so `selinux_context_elevation_for_sudo`
  passes; `staff_u` (not `sysadm_u`) so SSH login isn't gated by `ssh_sysadm_login`.
  BENCH-VERIFY admin SSH login + sudo + privileged ops under confinement, and
  **re-check reproducibility** (semanage rebuilds the policy store → possible
  verity-hash drift). The triage waivers/decisions live in the tailoring +
  docs/stig-deviations.md #12; the generated report should show 0–1 REVIEW.
 - NTP via DHCP option 42 → chrony (no public-pool egress): confirm on a booted
  host `chronyc sources` lists the DHCP-handed lab server (not `*.pool.ntp.org`).
  Assumes (a) NM exports the lease's NTP servers to the dispatcher as
@@ -493,7 +493,10 @@ build {
    destination = "/tmp/"
  }
  provisioner "shell" {
-    environment_vars = ["ENABLE_STIG=${var.enable_stig}"]
+    environment_vars = [
      "ENABLE_STIG=${var.enable_stig}",
      "ADMIN_USER=${var.admin_user}",
    ]
    inline = [
      "set -e",
      "if [ \"$ENABLE_STIG\" != \"true\" ]; then echo 'enable_stig=false -> skipping STIG hardening.'; mkdir -p /root; echo '<html><body>STIG hardening disabled for this build (enable_stig=false).</body></html>' > /root/stig-report.html; : > /root/stig-arf.xml; exit 0; fi",
@@ -514,6 +517,63 @@ build {
      "echo \"==> Remediating against tailored STIG profile using $DS (this changes a lot)\"",
      # --remediate returns nonzero when rules remain failed (expected) — tolerate.
      "oscap xccdf eval --remediate --profile xccdf_org.ssgproject.content_profile_stig_diskless --tailoring-file /etc/stig/diskless-tailoring.xml --results-arf /root/stig-arf.xml --report /root/stig-report.html \"$DS\" || true",
      # --- Supplemental remediations (report triage 2026-06-19, scan app-9f7d8d1).
      # Applied BETWEEN --remediate and the clean eval so the report of record
      # reflects them. See docs/stig-deviations.md #12.
      # (a) postfix: remove the unused local MTA. The appliance sends no mail and
      #     ships audit off-box via rsyslog (2f), so an MTA is dead surface. This
      #     makes postfix_prevent_unrestricted_relay N/A; package_postfix_installed
      #     is waived in the tailoring to match.
      "echo '==> supplemental: removing unused MTA (postfix)'",
      "dnf remove -y postfix >/dev/null 2>&1 || true",
      # (b) USBGuard: usbguard is already installed + enabled, but its policy was
      #     generated on the build VM (no real USB input). Add the LinuxAudit audit
      #     backend (configure_usbguard_auditbackend) AND a hardware-independent
      #     HID/hub allowlist so a physical console keyboard/mouse keep working
      #     under the default block target (a plain keyboard = HID only, a keyboard
      #     with built-in hub = HID+hub, so all three allow forms are needed).
      #     BENCH-VERIFY physical console input on real hardware.
      "echo '==> supplemental: usbguard LinuxAudit backend + HID/hub allowlist'",
      "if rpm -q usbguard >/dev/null 2>&1; then",
      "  [ -f /etc/usbguard/usbguard-daemon.conf ] || touch /etc/usbguard/usbguard-daemon.conf",
      "  sed -i '/^[ \\t]*AuditBackend=/Id' /etc/usbguard/usbguard-daemon.conf",
      "  printf 'AuditBackend=LinuxAudit\\n' >> /etc/usbguard/usbguard-daemon.conf",
      "  touch /etc/usbguard/rules.conf",
      "  for rule in 'allow with-interface match-all { 03:*:* }' 'allow with-interface match-all { 09:00:* }' 'allow with-interface match-all { 03:*:* 09:00:* }'; do",
      "    grep -qF \"$rule\" /etc/usbguard/rules.conf || printf '%s\\n' \"$rule\" >> /etc/usbguard/rules.conf",
      "  done",
      "  restorecon /etc/usbguard/usbguard-daemon.conf /etc/usbguard/rules.conf 2>/dev/null || true",
      "else",
      "  echo 'WARNING: usbguard not installed; skipping (configure_usbguard_auditbackend stays a finding).'",
      "fi",
      # (c) selinux_context_elevation_for_sudo: STIG wants sudo to ELEVATE the
      #     SELinux context. SSG ships no auto-fix. Decision (2026-06-20):
      #     REMEDIATE WITH CONFINEMENT. Two parts:
      #       1. Rewrite the admin sudoers rule to add the role/type transition
      #          (KEEP NOPASSWD — the admin is key-only; #8). This is what the
      #          OVAL check looks for, so it makes the rule pass.
      #       2. Map the admin to the confined **staff_u** SELinux user so the
      #          staff_r->sysadm_r sudo transition is actually authorized at
      #          runtime (unconfined_u cannot reach sysadm_r). staff_u (NOT
      #          sysadm_u) so SSH login isn't gated by the ssh_sysadm_login bool.
      #     ⚠ BENCH-VERIFY: admin SSH login succeeds AND `sudo` works AND every
      #     privileged op the admin needs runs under the sysadm_t transition. If
      #     this locks the admin out, enable_stig=false is the escape hatch and
      #     this rule reverts to a justified deviation. ⚠ REPRODUCIBILITY: confirm
      #     the verity hash is stable across two builds — semanage rebuilds the
      #     SELinux policy store and may write nondeterministic content; if it
      #     drifts, normalize in 2d.
      "if [ -n \"$ADMIN_USER\" ] && id \"$ADMIN_USER\" >/dev/null 2>&1; then",
      "  echo \"==> supplemental: sudo SELinux elevation — confining $ADMIN_USER to staff_u + sudoers role/type\"",
      "  command -v semanage >/dev/null 2>&1 || dnf install -y policycoreutils-python-utils",
      "  printf '%s ALL=(ALL) TYPE=sysadm_t ROLE=sysadm_r NOPASSWD:ALL\\n' \"$ADMIN_USER\" > \"/etc/sudoers.d/$ADMIN_USER\"",
      "  chmod 0440 \"/etc/sudoers.d/$ADMIN_USER\"",
      "  visudo -cf \"/etc/sudoers.d/$ADMIN_USER\"",
      "  restorecon \"/etc/sudoers.d/$ADMIN_USER\"",
      "  if semanage login -l 2>/dev/null | grep -qE \"^$ADMIN_USER[[:space:]]\"; then semanage login -m -s staff_u \"$ADMIN_USER\"; else semanage login -a -s staff_u \"$ADMIN_USER\"; fi",
      "  restorecon -R \"/home/$ADMIN_USER\" 2>/dev/null || true",
      "  echo \"==> $ADMIN_USER mapped to staff_u; sudo elevates to sysadm_r/sysadm_t\"",
      "fi",
      # Clean post-remediation eval = the report/ARF of record (no --remediate).
      "oscap xccdf eval --profile xccdf_org.ssgproject.content_profile_stig_diskless --tailoring-file /etc/stig/diskless-tailoring.xml --results-arf /root/stig-arf.xml --report /root/stig-report.html \"$DS\" || true",
      # GUARD: a scan with 0 evaluated rules (everything notapplicable/notselected)
@@ -5,7 +5,7 @@ Persistent backlog, kept in sync with the working session task tracker. Status:
 ---
-## Current build posture (LAB / test) — as of 2026-06-18
+## Current build posture (LAB / test) — as of 2026-06-19
 The image currently builds in **open-network test mode**. These toggles must be
 flipped back for a secure/production build (consolidated as item #8):
@@ -15,12 +15,24 @@ flipped back for a secure/production build (consolidated as item #8):
  per-env DNS name like `nvme.fleet.lab` once DNS-at-boot is trusted).
 - Unsigned UKI (`sb_key`/`sb_cert` not passed) → Secure Boot must be OFF on the
  test target. Production needs CI/HSM signing.
- `enable_kiosk=false` by default (CI may set true); `enable_stig=true`;
+- `enable_kiosk=true`; `boot_splash=true`; NTP via DHCP→serving-host chrony.
-  `boot_splash=true`; NTP via DHCP→serving-host chrony.
+- **`enable_stig` / CI `ENABLE_STIG="false"` RIGHT NOW** — temporarily disabled
  to get a working box while the STIG regressions were diagnosed (now fixed,
  below). **Flip back to `true`** and bench-verify the hardened build.
 - **`debug_shell=true` (DEBUG HOLE — passwordless root on tty2). REMOVE before
  prod** (`-var debug_shell=false`). Note: it didn't actually come up on tty2 in
  testing; diagnosis ended up done via offline `rootfs.erofs` mount + SMBIOS
  `enforcing=0`. SMBIOS cmdline-extra works on Proxmox only after a full VM
  **stop/start** (not `reset`).
 - **Admin SSH key MUST be ECDSA or RSA, NOT ed25519**, when STIG is on — the STIG
  crypto policy drops ed25519 from sshd's accepted pubkey algorithms. Set the
  `SSH_AUTHORIZED_KEY` CI secret to an ECDSA/RSA key (see #2).
 - **Hostname:** image is hostname-neutral (empty `/etc/hostname`,
  `hostname-mode=default`); the serving dnsmasq's `fleet-namer` (`--dhcp-script`)
  assigns a stable creative starship name per MAC (e.g. `nebula-vanguard-07`) via
  DHCP option 12 + DNS A/PTR. Host picks it up on next DHCP renewal/reboot.
 - **Serving `.env`:** must set `AUDIT_HOST=audit.fleet.lab` (+ `docker compose up
  -d dnsmasq` to reload) for remote log offload to resolve/flow.
 What's working/verified vs awaiting bench is per-item below. Cross-cutting
 bench-verify checklist lives in `CLAUDE.md` → "Known bench-verify items".
@@ -78,8 +90,13 @@ in **[stig-deviations.md](stig-deviations.md)** (curated register) and reported
 per-build by **[../scripts/stig-deviations.sh](../scripts/stig-deviations.sh)**
 (non-pass rules tagged intentional vs REVIEW); CI publishes
 `stig-report.html` + `stig-arf.xml` + `stig-deviations.md`. Scanner tooling is
-removed from the shipped image. **BENCH-VERIFY:** boot/login still work;
+removed from the shipped image. **BENCH-VERIFY:** boot/login **VERIFIED ON THE
-reproducible verity hash across two builds; triage REVIEW rows.
+BENCH 2026-06-19** — hardened build with `enable_stig=true`, host
 `cygnus-cruiser-99`: kiosk auto-starts + renders, admin SSH (ECDSA) logs in,
 audit offload reaches the collector, DHCP creative hostname applied, NVMe/TCP
 verity root mounts and the host stays up. **STILL OPEN:** reproducible verity
 hash across two builds; triage the REVIEW rows (below); the secure path (#8,
 802.1X/MACsec — this was the `disable_dot1x=true` test path).
 **FINDING 2026-06-18 (FIXED) — false-clean scan.** The first hardened build
 (branch `hardening`, `ada4aa4`) produced a report reading "0 REVIEW / clean",
@@ -107,34 +124,101 @@ two appliance accounts — `chage -M -1 -m 0 -I -1 -E -1` + `faillock --reset`;
 kiosk uses a dedicated `/etc/pam.d/kiosk` (`PAMName=kiosk`, permissive account /
 full session for seat); sshd gets an `account sufficient pam_succeed_if.so user
 = fleetadmin` first-rule bypass. Scoped to those two accounts; everyone else
-keeps full STIG. Justified as register deviation #10. **Bench-verify on rebuild:
+keeps full STIG. Justified as register deviation #10. **VERIFIED ON THE BENCH 2026-06-19**
-kiosk renders + admin SSH works with hardening on.**
+(`enable_stig=true`, host `cygnus-cruiser-99`): kiosk auto-starts + renders and
 admin SSH (ECDSA key) logs in with hardening on.**
 **UPDATE 2026-06-19 — offline erofs inspection of the hardened image (mounted
 `rootfs.erofs` read-only) pinned the real causes; the PAM-account theory above
 was incomplete:**
- **Kiosk = fapolicyd (CONFIRMED).** fapolicyd is `enabled` and `kiosk-session`
+- **Kiosk had TWO causes, both FIXED:**
-  was not in its trust → it blocks `/usr/local/bin/kiosk-session`. Fix: KEEP
+  1. **fapolicyd** is `enabled` and `kiosk-session` wasn't in its trust → it
-  fapolicyd (it's the exec-guard for the writable overlay dm-verity can't cover)
+     blocked `/usr/local/bin/kiosk-session`. Fix: KEEP fapolicyd (it's the
-  and add the kiosk binary to its trust DB at build (2c-STIG-postfix). Not waived.
+     exec-guard for the writable overlay dm-verity can't cover) and add the kiosk
- **SSH = NOT a STIG/PAM/SELinux issue.** `enforcing=0` didn't help; pam_namespace
+     binary to its trust DB at build (2c-STIG-postfix). Not waived.
-  is inert (empty namespace.conf); account bypass present; key file + perms +
+  2. **Auto-start:** kiosk was `WantedBy=graphical.target` but the host boots to
-  sshd config all correct. Remaining cause: **baked key mismatch** — the
+     `multi-user.target` (graphical never reached) → unit `inactive (dead)` at
-  `SSH_AUTHORIZED_KEY` CI secret bakes `audiobuzz@s3`
+     boot, fine on manual `restart`. Fix: `WantedBy=multi-user.target` + dropped
-  (`SHA256:30p4vOQdWk0TdRQIR3VMo95yc6I7cRmCwIBRVjIHaV4`); if the client uses a
+     `set-default graphical.target` (kiosk launches weston directly, needs no DM
-  different private key → `Permission denied (publickey)`. AWAITING client
+     target).
-  fingerprint / `ssh -vvv` to confirm; fix is the secret, not code.
+- **SSH = STIG crypto policy excludes ed25519 (CONFIRMED via `ssh -vvv`).** The
- Side note: SMBIOS cmdline-extra injection works only after a Proxmox VM
+  key fingerprint MATCHED (not a mismatch); the server's `server-sig-algs`
-  **stop/start** (not `reset`); and the debug-shell-on-tty2 attempt did not come
+  advertised only ecdsa + rsa-sha2 — **no `ssh-ed25519`** — so the ed25519 admin
-  up — diagnosis ended up done via offline erofs mount instead.
+  key is rejected at the signature stage (before PAM/SELinux, which is why
  `enforcing=0` and the account-bypass didn't help). **Fix (your action): set the
  `SSH_AUTHORIZED_KEY` CI secret to an ECDSA (`ssh-keygen -t ecdsa -b 384`) or RSA
  key**, then rebuild. No code change. (Alt: re-allow ed25519 via
  `PubkeyAcceptedAlgorithms +ssh-ed25519` in the sshd drop-in — but that's a
  non-approved algo and would re-fail a STIG rule; prefer the ECDSA key.)
 - **rsyslog TLS-offload rules waived (lab):** `rsyslog_encrypt_offload_*` force
  gtls+x509+CA and broke the plaintext `2f` forward → unselected in the
  tailoring; production TLS offload tracked under #8.
 - Diagnosis tooling notes: SMBIOS cmdline-extra works only after a Proxmox VM
  **stop/start** (not `reset`); the debug-shell-on-tty2 never came up — the
  decisive diagnosis was **offline `rootfs.erofs` mount** + `ssh -vvv` +
  `enforcing=0`.
 **REVIEW-ROW TRIAGE — DONE 2026-06-19 (scan `app-9f7d8d1`, 21 REVIEW → 1 open).**
 The post-fix hardened scan was valid (398 pass / 12 fail / 9 notchecked). All 21
 REVIEW rows dispositioned (full detail: [stig-deviations.md](stig-deviations.md)
 #12). Mechanics: a rule only stops being flagged REVIEW if it's `selected="false"`
 in `diskless-tailoring.xml` (the register prose alone doesn't clear it) or made to
 pass / N/A.
  - **Bucket A (waived, register-justified):** `encrypt_partitions`,
    `auditd_audispd_configure_sufficiently_large_partition` (#1); `grub2_password`
    (#2); `sysctl_crypto_fips_enabled`, `harden_sshd_macs_openssh_conf_crypto_policy`,
    `harden_sshd_macs_opensshserver_conf_crypto_policy` (#5);
    `configured_firewalld_default_deny` (#4); `sssd_enable_certmap`,
    `sssd_has_trust_anchor` (#7).
  - **Bucket B (waived N/A):** `account_temp_expire_date`,
    `accounts_user_home_paths_only`, `libreswan_approved_tunnels`,
    `security_patches_up_to_date`, `ssh_keys_passphrase_protected`.
  - **Bucket C (decisions applied):** `installed_OS_is_vendor_supported` (Rocky IS
    supported; RHEL-datastream CPE artifact — waived), `network_configure_name_resolution`
    (single DHCP DNS by design — waived), `sysctl_user_max_user_namespaces_no_remediation`
    (KEEP userns for Chromium sandbox — waived), `accounts_authorized_local_users`
    (appliance accounts authorized, #10 — waived; prod: set the authorized-users
    regex var instead), `package_postfix_installed` + `postfix_prevent_unrestricted_relay`
    (**postfix removed** in 2c-STIG — no MTA needed; audit goes off-box via 2f),
    **USBGuard** `configure_usbguard_auditbackend` + `usbguard_allow_hid`/`_hub`/
    `_hid_and_hub` (**ENABLED + enforcing**: LinuxAudit backend + hardware-independent
    HID/hub allowlist written in 2c-STIG; ⚠ BENCH-VERIFY physical console keyboard/
    mouse on real hardware — the build-VM-generated policy + default block target
    would otherwise lock out console input).
  - **`selinux_context_elevation_for_sudo` — REMEDIATED WITH CONFINEMENT
    (decision 2026-06-20).** 2c-STIG now rewrites the admin sudoers to
    `TYPE=sysadm_t ROLE=sysadm_r NOPASSWD:ALL` and maps the admin to **`staff_u`**
    (`semanage login`) so the sudo role transition is authorized. ⚠ **TWO BENCH
    GATES:** (a) admin SSH login + sudo + privileged ops must work under `staff_u`
    confinement (escape hatch: `enable_stig=false` → reverts to a justified
    deviation); (b) **reproducibility** — `semanage` rebuilds the policy store;
    confirm the verity hash is stable across two builds (normalize in 2d if it
    drifts). Needs `policycoreutils-python-utils` (installed in 2c-STIG if absent).
  **Expected next-build report: 0–1 REVIEW** (0 if both postfix→N/A and
  usbguard→pass land and sudo confinement holds; the triage was validated by
  re-running `scripts/stig-deviations.sh` against the app-9f7d8d1 ARF with the new
  tailoring — 21 REVIEW → 3, where the 3 are exactly postfix/usbguard/sudo, all
  addressed for the next build).
 Remaining (future hardening, currently waived — see the register): FIPS,
 firewall, per-host/rotatable admin access. **Remote audit offload — WIRED both
 ends** (2026-06-19): receiver `serving/audit-collector/` (rsyslog TCP/514,
 per-source-host files) + sender in the image (provisioner 2f, `audit_host` var:
 audisp-syslog→LOCAL6 + rsyslog `omfwd` to `audit.fleet.lab`). Lab is plaintext;
-TLS/RELP is the remaining hardening. **Bench-verify:** booted host's auditd AVCs
+TLS/RELP is the remaining hardening. **VERIFIED END-TO-END ON THE BENCH
-land in `audit-collector/logs/<ip>/audit.log` and journal in `messages.log`.
+2026-06-19** — booted host `cygnus-cruiser-99` (192.168.50.148) forwards to the
 collector, which writes `audit-collector/logs/192.168.50.148/{audit,messages}.log`.
 **Serving-host firewall gotcha hit + fixed:** the collector is host-networked so
 the serving host's **ufw** governs :514 (Docker doesn't manage iptables for
 host-net containers); 514/tcp was bound to the wrong NIC (`ens18` instead of the
 boot-LAN `ens19`), so SYNs were silently dropped (`SYN-SENT` / "connection timed
 out", not refused). Fix: `ufw allow in on ens19 to any port 514 proto tcp`. The
 sender's `action.resumeRetryCount="-1"` buffered the backlog and drained on
 reconnect — no records lost. Documented in
 [../serving/audit-collector/README.md](../serving/audit-collector/README.md).
 When the **workstation** firewall is re-enabled (#4 / register #4) it needs the
 reciprocal **egress** allow for 514/tcp to the collector.
 ### Original spec (retained for reference)
@@ -0,0 +1,221 @@
 # Annex A — ISM Control Cross-Reference & Residual Risk Register
 > **Protective marking:** `OFFICIAL: Sensitive` *(inherits the parent
 > [SSP](ssp.md) marking; set per system classification).*
 >
 > **Companion to:** [System Security Plan](ssp.md). Read the SSP first for system
 > description, boundary and roles.
 >
 > **A&A framework:** ASD *Information Security Manual* (ISM) — engagement target
 > **May 2026 release**.
 ---
 ## How to read this annex
 This annex does two things:
 1. **§2 — ISM control cross-reference:** maps the ISM control set (by guideline
   chapter) to *how this system implements it*, with an implementation **status**
   and a pointer to any **residual risk**.
 2. **§3 — Residual risk register:** the consolidated, rated list of residual
   risks (`R-NN`), each with ISM linkage, compensating controls, treatment and
   owner. This is the artifact the Authorising Officer reasons over.
 ### ⚠ Control-identifier currency caveat
 The `ISM-NNNN` identifiers below are **representative** and were drafted against
 an understanding of the ISM to a **January 2026 baseline**. The ISM is reissued
 quarterly and **renumbers/adds/retires controls between releases.** Before this
 annex is relied upon for assessment, the **IRAP assessor MUST reconcile every
 identifier against the actual May 2026 ISM**, confirm no newly-introduced
 controls are unmapped, and confirm none of the cited controls were retired. Where
 an exact number is uncertain it is shown as `ISM-NNNN*` (asterisk = *verify
 number*). The **control intent and the system's implementation** are the durable
 content here; the numbers are a convenience for the assessor.
 ### Status legend
 | Status | Meaning |
 |---|---|
 | **Implemented** | Control is in place and operating in the current build. |
 | **Partial** | Implemented but incomplete, or scoped to lab config. |
 | **Planned** | On the roadmap / POA&M; not yet implemented. |
 | **N/A (justified)** | Structurally not applicable to a diskless/UKI/immutable design; compensating control noted. |
 | **Waived** | Deliberately not met; documented in the [STIG deviation register](stig-deviations.md) and/or a residual risk here. |
 ### Risk rating scale
 Likelihood × Consequence → **Low / Medium / High / Critical** (qualitative,
 ISM/PSPF style). Ratings are **pre-treatment** unless stated; the AO accepts the
 **post-treatment residual**.
 ---
 ## 2. ISM control cross-reference
 ### 2.1 Guidelines for Security Documentation
 | Topic | ISM (rep.) | Requirement intent | System implementation | Status | Residual |
 |---|---|---|---|---|---|
 | System Security Plan | ISM-0041* | An SSP is developed and maintained. | This document set ([SSP](ssp.md) + this annex). | Partial | Formal sign-off, role appointment pending. |
 | Incident Response Plan | ISM-0043* | An IRP is developed, maintained, exercised. | Not yet authored; inherent recovery via reboot/redeploy. | Planned | R-12 |
 | Continuous monitoring plan | ISM-1163* | Continuous monitoring strategy documented. | auditd + log offload exist; plan not formalised. | Partial | R-07 |
 | Strategies maintained & approved | ISM-0027* | Documentation approved by the authorising authority. | Pending AO appointment & approval. | Planned | — |
 ### 2.2 Guidelines for Cyber Security Roles
 | Topic | ISM (rep.) | Requirement intent | System implementation | Status | Residual |
 |---|---|---|---|---|---|
 | CISO / system owner appointed | ISM-0714*, ISM-1071* | Defined accountable security roles. | Roles identified in [SSP §3]; appointments TBA. | Planned | — |
 | System-specific security roles | ISM-1525* | Administrators with defined responsibilities. | Platform team operates build/release & runtime. | Partial | R-05 |
 ### 2.3 Guidelines for System Hardening — Operating systems & applications
 | 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` with documented tailoring ([stig-deviations.md](stig-deviations.md)). | Partial | R-03 (CI report-only/disabled now) |
 | Application control / allow-listing | ISM-0843*, ISM-1490*, ISM-1657* | Only approved executables run. | **fapolicyd** (RPM-trust + one trusted kiosk binary) + immutable dm-verity root. | 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 | — |
 | 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) | — |
 ### 2.4 Guidelines for System Hardening — Authentication
 | 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** (`0x81010001`), cert in TPM NV. | Partial | R-01 (not bench-verified; disabled in test builds), R-08 (placeholder CA) |
 | Privileged access restricted | ISM-1507*, ISM-0445* | Limit & control admin access. | Single key-only `wheel` admin; root login disabled. | 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 |
 | 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
 | Topic | ISM (rep.) | Requirement intent | System implementation | Status | Residual |
 |---|---|---|---|---|---|
 | Patching / vulnerability remediation | ISM-1493*, ISM-1144*, ISM-1472* | Timely patching. | Patch = **rebuild + re-sign + redeploy a new digest**; atomic, uniform fleet update; cadence/SLA to define. | Partial | R-10 (patch SLA undefined) |
 | Secure build & change control | ISM-1483* | Controlled, repeatable builds. | Reproducible Packer build in CI; digest-pinned deployment; one commit/release; rollback = revert commit. | Implemented | — |
 | 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)** |
 ### 2.6 Guidelines for System Monitoring (event logging)
 | Topic | ISM (rep.) | Requirement intent | System implementation | Status | Residual |
 |---|---|---|---|---|---|
 | Centralised event logging | ISM-0988*, ISM-1405* | Logs centrally collected. | `audisp-syslog`→rsyslog `omfwd` (disk-assisted queue) → dedicated collector (`serving/audit-collector/`). | Partial | R-07 |
 | Required events logged | ISM-0582*, ISM-1537* | Log security-relevant events. | STIG auditd rule set; kernel `audit=1`, `audit_backlog_limit=8192`. | Implemented | — |
 | Protect logs in transit | ISM-1432*, ISM-0407* | Encrypt/authenticate log transport. | **Plaintext** offload on isolated 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; retention policy & tamper-protection not yet defined. | Planned | R-07 |
 | Event log analysis / alerting | ISM-0109*, ISM-1228* | Review logs; alert on incidents. | No SIEM correlation/alerting defined. | Planned | R-07, R-12 |
 ### 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 |
 | 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 | — |
 ### 2.8 Guidelines for Communications Infrastructure / Systems
 | Topic | ISM (rep.) | Requirement intent | System implementation | Status | Residual |
 |---|---|---|---|---|---|
 | Link-layer encryption (cable/fabric) | ISM-1187*, ISM-0181* | Protect data on the link. | **MACsec** on the access link (encryption + integrity), keyed via MKA after EAP. | Partial | R-01 (MKA survival across switch-root not yet bench-verified) |
 ### 2.9 Guidelines for Cryptography
 | 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 | — |
 | 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
 | Topic | ISM (rep.) | Requirement intent | System implementation | Status | Residual |
 |---|---|---|---|---|---|
 | Media sanitisation / no data remanence | ISM-0347*, ISM-1218* | Prevent data remanence. | **Diskless** — no persistent local media; writable layer is **RAM tmpfs**, gone at power-off. | Implemented | — |
 | Tamper-evidence / boot integrity | ISM-1542*, ISM-0312* | Detect firmware/boot tampering. | **UEFI Secure Boot** + signed UKI + immutable signed cmdline + dm-verity; TPM measurements available for attestation. | Partial | R-11 (remote attestation not yet implemented) |
 | Device identification | ISM-1195* | Uniquely identify devices. | Identity derived from TPM cert (hostnqn from cert serial); no spoofable per-host config. | Implemented | — |
 ### 2.11 Guidelines for Procurement, Outsourcing & Evaluated Products
 | Topic | ISM (rep.) | Requirement intent | System implementation | Status | Residual |
 |---|---|---|---|---|---|
 | Supply-chain / artifact integrity | ISM-1567*, ISM-1568* | Trustworthy software supply chain. | FROM-scratch OCI artifact; SHA256SUMS; digest-pinned manifest; reproducible build. | Implemented | — |
 | Evaluated/ supported products | ISM-0280*, ISM-1467* | Prefer evaluated/vendor-supported. | RHEL/Rocky 9 (vendor-supported); TPM 2.0; evaluation status of crypto to confirm. | Partial | R-06 |
 ---
 ## 3. Residual risk register
 Ratings are **pre-treatment** → with the **post-treatment residual** the AO is
 asked to accept. Treatments map to [docs/TODO.md](TODO.md) (working POA&M).
 | ID | Residual risk | ISM linkage | Likelihood × Consequence → **Rating** | Existing compensating controls | Treatment (POA&M) | Post-treat. residual | Owner / target |
 |---|---|---|---|---|---|---|---|
 | **R-01** | Secure path (802.1X EAP-TLS + MACsec) **implemented but not bench-verified end-to-end**; disabled in test builds (`disable_dot1x=true`). Until verified, devices may attach to an unauthenticated/unencrypted link. | 2.4, 2.7, 2.8 (ISM-1546*, 0520*, 1187*) | Likely × Major → **High** | Test path on an isolated lab LAN; full auth stack present (dormant); design follows ASD intent. | Full boot-chain bench test (swtpm + hostapd + FreeRADIUS): port `Authorized`, macsec0 addressed, MKA survives switch-root, NVMe root mounts. Re-enable in CI. | **Low** (once verified) | Platform team — *before production ATO* |
 | **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 currently **report-only / disabled in CI** (`enable_stig=false`); shipped images may be unhardened. | 2.3 (ISM-1407*/1408*) | Possible × Major → **Medium** | Tailoring + register exist; SELinux/fapolicyd still on; re-enable is a single flag. | Flip `ENABLE_STIG="true"`; confirm scan evaluates >0 rules; triage REVIEW rows (buckets A/B/C in TODO #2). | **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, 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-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**, **single-site**, **no SIEM alerting**; logs interceptable/repudiable and not actively reviewed. | 2.6 (ISM-1432*/0109*/0859*) | Possible × Moderate → **Medium** | Isolated LAN; disk-assisted queue (no loss on collector blip); auditd local copy; per-source files. | rsyslog **TLS** (gtls/6514) + bundle CA in image (re-select the 3 waived `rsyslog_encrypt_offload_*` rules); define retention + integrity; forward to SIEM with alerting. | **Low** | Platform/SecOps — *production* |
 | **R-08** | **Placeholder RADIUS CA** (`files/etc/dot1x/radius-ca.pem`) — real EAP-TLS trust anchor not provisioned; auth cannot succeed and trust is unestablished. | 2.4 (ISM-1546*) | Certain (lab) × Major → **Medium** | Documented as a placeholder; environment-specific provisioning is the intended path; no real CA committed. | Provision the environment's real RADIUS CA out-of-band (not committed unless classification permits). | **Low** | Environment owner — *before production* |
 | **R-09** | **Host firewall disabled**; host exposes more network surface than necessary. | 2.7 (ISM-1416*) | Possible × Moderate → **Low–Medium** | Isolated LAN; minimal services; egress controlled at the network/serving layer; no kiosk inbound. | Re-enable firewalld with explicit allow rules (NVMe/TCP `:4420`, DHCP, log offload, SSH) once the secure path is verified. | **Low** | Platform/network — *after R-01* |
 | **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* |
 ### 3.1 Risk heatmap (post-treatment targets)
 ```
 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
 ( * = currently High pre-treatment; all targeted to Low after treatment )
 ```
 *The heatmap shows pre-treatment positions; every item has a treatment to Low /
 Low–Medium. The AO is asked to authorise on the basis that R-01, R-02, R-03, R-08
 and R-12 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.*
 ---
 ## 4. Assessor notes / open items for the IRAP assessment
 1. **Reconcile all `ISM-NNNN*` identifiers** against the May 2026 ISM (see
   currency caveat) and confirm no new controls are unmapped.
 2. **Confirm the system data classification** with the System Owner — it sets the
   required control baseline and may reclassify several "N/A/accepted" items
   (notably R-06 cryptography) as mandatory.
 3. **Witness the secure-path bench test** (R-01) — this is the central
   effectiveness check; the rest of the architecture's value is contingent on it.
 4. **Verify reproducibility** — two builds → identical `verity.json` root hash
   (build-integrity control evidence).
 5. **Review the STIG generated report** for the build under assessment — every
   non-pass rule should map to the [deviation register](stig-deviations.md);
   anything flagged **REVIEW** is an unjustified finding.
 6. **Confirm lab-only flags are off** in the assessed build: `debug_shell=false`,
   `enable_stig=true`, `disable_dot1x=false`, real RADIUS CA in place.
 ---
 *End of Annex A.*
@@ -0,0 +1,261 @@
 # System Security Plan (SSP) — Diskless Fleet Boot System
 > **Protective marking:** `OFFICIAL: Sensitive` *(sample marking — set per the
 > organisation's classification of the highest-sensitivity data the system
 > handles; an SSP that describes the security architecture is normally marked at
 > or one level above the system's data classification.)*
 >
 > **A&A framework:** Australian Government — Protective Security Policy Framework
 > (PSPF) + ASD *Information Security Manual* (ISM). This document is the **System
 > Security Plan** required by the ISM *Guidelines for cyber security
 > documentation* and is the primary input to the IRAP security assessment and the
 > Authorising Officer's authorisation (ATO) decision.
 | Field | Value |
 |---|---|
 | System name | Diskless Fleet Boot System ("the fleet") |
 | Document type | System Security Plan (SSP) |
 | Version | 0.1 (DRAFT — pre-assessment) |
 | Date | 2026-06-19 |
 | Author / maintainer | System Owner (delegate) |
 | Status | Lab / pre-production. 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) |
 > **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
 > baseline. The engagement specifies the **May 2026 ISM**. The ISM is reissued on
 > a quarterly cadence and **control identifiers are added, retired and
 > renumbered between releases.** Every `ISM-NNNN` identifier in Annex A is
 > therefore **representative and MUST be validated by the IRAP assessor against
 > the actual May 2026 release** before the assessment is relied upon. The
 > *intent* of each control mapping is stable; the *number* may not be.
 ---
 ## 1. Purpose and scope
 This SSP describes the security architecture, the security controls implemented,
 and the residual risk of the **Diskless Fleet Boot System** — a fleet of
 diskless workstations that network-boot a signed, immutable operating system over
 the wire and hold **no persistent local state**. It supports an Australian
 **Assessment and Authorisation (A&A)** process: it is the document an IRAP
 assessor evaluates to produce the Security Assessment Report (SAR), and that the
 Authorising Officer (AO) uses to make a risk-based **Authority to Operate (ATO)**
 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.
 **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.
 ## 2. System description
 ### 2.1 Overview
 Each host is **diskless**: it has no installed operating system and no writable
 persistent storage that participates in identity. At power-on it performs UEFI
 **HTTP boot**, fetches a **signed Unified Kernel Image (UKI)**, and assembles a
 running system whose root filesystem is an **immutable, cryptographically
 verified image mounted over the network**. All host identity is derived **at
 runtime from a hardware Trusted Platform Module (TPM)**; nothing host-specific
 exists in any build artifact.
 A release is a **signed UKI** plus a root image, packaged together as a
 **FROM-scratch OCI artifact image** and pinned by digest in a deployment
 manifest. One commit = one release = one digest = one manifest entry.
 ### 2.2 Boot and trust chain (control flow)
 1. **UEFI Secure Boot** measures and verifies the UKI signature (vendor/Secure
   Boot key) before execution.
 2. **UKI (systemd-stub)** carries the kernel, the `--no-hostonly` initramfs, and
   an **immutable, signed kernel command line** (includes the dm-verity root
   hash and STIG kernel parameters). No GRUB.
 3. **Initramfs (dracut)** brings up the NIC and performs **802.1X EAP-TLS**
   network authentication using a **private key held in the TPM** (persistent
   handle `0x81010001`); the client certificate is read from TPM NV index
   `0x01800001`.
 4. On authorisation, **MACsec** is established on the access link (link-layer
   encryption/integrity); the host then obtains an IP **on the MACsec interface**
   via DHCP.
 5. The host connects its **root over NVMe/TCP**, maps it through **dm-verity**
   (block-level integrity against the signed root hash in the UKI cmdline), and
   mounts the **erofs** read-only root.
 6. A **tmpfs (RAM) volatile overlay** (`systemd.volatile=overlay`) provides the
   writable layer. It is discarded at power-off — the host returns to a known,
   verified state every boot.
 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.
 ### 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. Each crossing is a control point addressed in Annex A.
 ### 2.4 Data and classification
 - **Data at rest in the artifact:** none that is host-specific or sensitive. The
  image is generic to the whole fleet by design (Architecture invariant #1 — *no
  per-host state in any artifact, ever*).
 - **Host identity / key material:** the EAP-TLS private key **never leaves the
  TPM**; the certificate is read from TPM NV. Signing keys for the UKI are
  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).
 - **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
 ISM control set.** The classification of the data rendered by the kiosk
 application and accessible from the workstation must be confirmed with the System
 Owner; this draft assumes an **OFFICIAL / OFFICIAL: Sensitive** working
 classification and should be re-baselined if the system processes PROTECTED or
 above (which raises additional ISM control obligations, e.g. ASD-approved
 cryptography enforcement, gateway controls, and stricter media handling).
 ## 3. Security governance and A&A roles
 | Role | Responsibility (PSPF/ISM) | Assignment |
 |---|---|---|
 | **Authorising Officer (AO)** | Accepts residual risk; grants/denies/revokes the ATO. | *TBA — appoint before assessment* |
 | **System Owner** | Accountable for the system's security posture and this SSP. | *TBA* |
 | **Chief Information Security Officer (CISO)** | Organisational cyber security oversight; advises the AO. | *TBA* |
 | **IRAP Assessor** | Independent assessment of control implementation effectiveness; produces the SAR. | *Engaged for assessment* |
 | **System Manager / Administrators** | Day-to-day operation, patching, incident response, continuous monitoring. | Fleet platform team |
 | **Build / release pipeline owner** | Integrity of the CI build, signing, and digest-pinned deployment. | Fleet platform team |
 ## 4. A&A process and status
 This system follows the ISM A&A lifecycle:
 1. **Define** the system, its boundary and data classification (this SSP §2).
 2. **Select** the applicable ISM controls (Annex A, driven by classification).
 3. **Implement** the controls (this SSP §5–§6; the codebase is the implementation
   of record).
 4. **Assess** — IRAP assessor evaluates effectiveness → **Security Assessment
   Report (SAR)**.
 5. **Authorise** — AO weighs residual risk (Annex A risk register) → **ATO**.
 6. **Monitor** — continuous monitoring and a maintained **Plan of Action &
   Milestones (POA&M)** (this repo's [TODO.md](TODO.md) is the working POA&M
   source).
 **Current status:** Pre-assessment **DRAFT**. The system is functional in a lab
 configuration. Several controls are **partial or deferred** and are tracked as
 residual risks with treatment plans (Annex A §3). The security-critical path
 (802.1X/MACsec) is **implemented but not yet bench-verified end-to-end** and is
 currently disabled in test builds (`disable_dot1x=true`) — this is the single
 largest gate on a production authorisation.
 ## 5. Security control implementation — by ISM cyber security principle
 The ISM organises controls under four principles: **Govern, Protect, Detect,
 Respond.** Annex A gives the line-by-line control cross-reference; this section
 summarises the implementation posture.
 ### 5.1 Govern
 - Documented architecture (design v2 + errata), enforced **architecture
  invariants** ([CLAUDE.md](../CLAUDE.md)), and a maintained backlog/POA&M.
 - Reproducible, **digest-pinned** releases; one release = one digest = one
  manifest commit; rollback = revert the commit.
 - Signing keys held outside the repo and build VM (CI/HSM).
 - *Gaps:* formal SRMP, IRP, and continuous-monitoring plan to be authored;
  A&A roles to be appointed (§3).
 ### 5.2 Protect
 - **Identity & authentication:** mutual **802.1X EAP-TLS** with a
  **non-exportable TPM key**; network access controlled at the switch port.
 - **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);
  **erofs** immutable filesystem; **reproducible** build (verity hash is a pure
  function of inputs).
 - **System hardening:** **DISA STIG** baseline via OpenSCAP/SSG with a documented
  tailoring; **SELinux enforcing**; **fapolicyd** application allow-listing (the
  exec guard for the writable RAM overlay that dm-verity cannot cover);
  **key-only SSH**, root login disabled, hardened ciphers/MACs/KEX; **kiosk
  lockdown** (single locked browser, no shell/navigation).
 - **No persistent attack surface:** diskless; overlay discarded each boot; no
  per-host secrets in the image.
 - *Gaps / decisions:* **FIPS OFF** (lab phase); **host firewall disabled**;
  NVMe/TCP and audit offload **plaintext on the isolated LAN**; NOPASSWD key-only
  admin; **placeholder RADIUS CA**. See Annex A residual risks.
 ### 5.3 Detect
 - **auditd** enabled with STIG audit rules; kernel `audit=1` +
  `audit_backlog_limit` in the signed cmdline.
 - **Centralised log offload** via rsyslog (`audisp-syslog` → rsyslog `omfwd`,
  disk-assisted queue) to a dedicated **audit collector** (`serving/audit-collector/`).
 - *Gaps:* offload currently **plaintext** (TLS planned, R-07); offload is
  **local site only**; no SIEM correlation/alerting defined yet.
 ### 5.4 Respond
 - Known-good recovery is **inherent**: a host returns to a verified state on
  reboot; a bad release is rolled back by reverting one manifest commit (digest
  pin).
 - *Gaps:* formal **Incident Response Plan**, log-retention policy, and
  break-glass/forensics procedure (the diskless model complicates live forensics
  — RAM overlay is volatile) to be authored.
 ## 6. Essential Eight alignment (indicative)
 The Essential Eight is mitigation guidance, not a substitute for the ISM, but the
 AO will expect a maturity view:
 | Mitigation | Posture | Notes |
 |---|---|---|
 | Application control | **Strong** | fapolicyd allow-listing + immutable verified root; only RPM-trusted (plus one trusted kiosk binary) executables run. |
 | 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 (NOPASSWD, see R-05); no per-host/rotatable model yet. |
 | 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. |
 | 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
 The full residual-risk register is **[Annex A §3](ssp-annex-a-ism-residual-risk.md#3-residual-risk-register)**.
 The headline residual risks the AO must explicitly accept or treat before a
 production ATO:
 | ID | Residual risk | Rating (pre-treatment) | Disposition |
 |---|---|---|---|
 | R-01 | Secure path (802.1X/MACsec) not yet bench-verified; currently disabled in test builds. | **High** | Treat — verify before production authorisation. |
 | 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 temporarily **report-only / disabled in CI** (`enable_stig=false`). | **Medium** | Treat — re-enable 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; no per-host or rotatable access model. | **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**, single-site, no SIEM alerting. | **Medium** | Treat — TLS offload + monitoring on roadmap. |
 | 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**. | **Low–Medium** | Accept (isolated LAN) / treat with explicit allow-rules. |
 Each is detailed, ISM-cross-referenced, rated and assigned a treatment in Annex A.
 ## 8. Continuous monitoring and maintenance
 - **Build-time assurance:** every release is reproducible (verity hash verified
  stable across two builds), the UKI/rootfs roothash coupling is a hard CI gate,
  and the STIG scan publishes a report + a deviations register per build.
 - **Runtime monitoring:** auditd + centralised log offload; host returns to a
  verified state each boot.
 - **POA&M:** [docs/TODO.md](TODO.md) is the live working POA&M; items feed Annex A
  treatments. The SSP and Annex A are re-baselined at each material architecture
  change and at each scheduled A&A review.
 ---
 *End of SSP. See [Annex A](ssp-annex-a-ism-residual-risk.md) for the ISM control
 cross-reference and the full residual-risk register.*
@@ -34,6 +34,79 @@ Posture decisions (2026-06-18, lab phase):
 | 11 | **Login banner content** (`banner_etc_issue`, `banner_etc_issue_net`, `banner_etc_motd`) | STIG requires the verbatim DoD/USG "you are accessing a U.S. Government Information System" text. This is a fictional starship fleet, not a USG system, so `/etc/issue{,.net}` + `/etc/motd` carry the fleet (ISV AURELIAN) notice instead (provisioner step 2e, `files/banner/fleet-issue`). The content rules therefore fail by design. | The banner **keeps its security function**: it still states authorized-crew-only, that the terminal is monitored/logged, and that unauthorized access is prohibited — only the wording is themed. `sshd_enable_warning_banner` (Banner is shown) still passes. |
 ## 12. Report triage 2026-06-19 (scan `app-9f7d8d1`)
 Triage of the 21 REVIEW rows from the post-fix hardened scan (398 pass / 12 fail
 / 9 notchecked — a valid scan). All but one are dispositioned below; the rule IDs
 are unselected in `diskless-tailoring.xml` (or made to pass / N/A) so they no
 longer surface as REVIEW. **Remaining open: `selinux_context_elevation_for_sudo`**
 (see end).
 **Waived — covered by an existing register entry (Bucket A):**
 - `encrypt_partitions`, `auditd_audispd_configure_sufficiently_large_partition` —
  single erofs+tmpfs root, no partitions (#1).
 - `grub2_password` — UKI, no GRUB (#2).
 - `sysctl_crypto_fips_enabled`, `harden_sshd_macs_openssh_conf_crypto_policy`,
  `harden_sshd_macs_opensshserver_conf_crypto_policy` — FIPS off (#5).
 - `configured_firewalld_default_deny` — firewall off for the lab boot LAN (#4).
 - `sssd_enable_certmap`, `sssd_has_trust_anchor` — no SSSD/PKI/smartcard; local
  key-only host, no domain join (#7).
 **Waived — architecturally absent, N/A (Bucket B):** `account_temp_expire_date`
 (no temporary accounts), `accounts_user_home_paths_only` (appliance accounts,
 fixed home layout), `libreswan_approved_tunnels` (no IPsec/libreswan),
 `security_patches_up_to_date` (rebuild-from-current model — a scanner can't assess
 patch currency against a future rebuild), `ssh_keys_passphrase_protected` (no
 private keys stored on the host; host keys regenerate per boot).
 **Waived — decisions (Bucket C):**
 - `installed_OS_is_vendor_supported` — Rocky **is** vendor-supported; the rule
  fails only because the RHEL datastream's CPE checks for an RHEL subscription.
 - `network_configure_name_resolution` — single DHCP-provided resolver by design
  on the boot LAN; the multi-DNS requirement is N/A to the netboot model.
 - `sysctl_user_max_user_namespaces_no_remediation` — **KEEP user namespaces
  enabled**: the Chromium kiosk sandbox requires them. Disabling userns would
  break the kiosk.
 - `accounts_authorized_local_users` — the authorized-users check doesn't know the
  key-only appliance accounts (`fleetadmin`, `kiosk`); they are authorized (see
  #10). *Production note: prefer setting the SSG authorized-users regex variable
  to assert these two explicitly rather than waiving the whole check.*
 - `package_postfix_installed` — **postfix removed** (provisioner 2c-STIG): the
  appliance sends no mail and ships audit off-box via rsyslog (2f), so a local
  MTA is dead attack surface. This also makes `postfix_prevent_unrestricted_relay`
  N/A. Audit-failure notification relies on the remote offload, not email
  (`auditd ... action_mail_acct` stays configured but is not the alerting path).
 **Remediated to pass (not waived):**
 - `configure_usbguard_auditbackend` + `usbguard_allow_hid` / `usbguard_allow_hub`
  / `usbguard_allow_hid_and_hub` — **decision: ENABLE USBGuard with enforcement.**
  usbguard was already installed + enabled, but its policy is generated on the
  build VM (no real USB), so under the default **block** target a physical console
  keyboard/mouse would be blocked. The provisioner now sets
  `AuditBackend=LinuxAudit` and writes a **hardware-independent HID + hub
  allowlist** (`allow with-interface match-all { 03:*:* }`, `{ 09:00:* }`, and the
  composite `{ 03:*:* 09:00:* }`) so console input survives while mass storage and
  other device classes are blocked. **⚠ BENCH-VERIFY physical console input on
  real hardware** — if a platform's input device doesn't match the HID/hub
  classes, fall back to a per-platform allow rule or re-waive
  `configure_usbguard_auditbackend`.
 **Remediated with confinement (decision 2026-06-20) — `selinux_context_elevation_for_sudo`:**
 SSG ships no automated fix; the STIG manual remediation
 (`... TYPE=sysadm_t ROLE=sysadm_r ...`) requires the admin to reach the
 `sysadm_r` role, which `unconfined_u` cannot. So the provisioner (2c-STIG) now
 (1) rewrites the admin sudoers rule to `<admin> ALL=(ALL) TYPE=sysadm_t
 ROLE=sysadm_r NOPASSWD:ALL` (keeps NOPASSWD — the admin is key-only, #8 — and is
 what the OVAL check matches), and (2) maps the admin to the confined **`staff_u`**
 SELinux user (`semanage login`) so the `staff_r`→`sysadm_r` sudo transition is
 authorized at runtime. `staff_u` (not `sysadm_u`) is used so SSH login isn't gated
 by the `ssh_sysadm_login` boolean. **⚠ Two bench gates before trusting:** (a)
 admin SSH login + `sudo` + every privileged op must work under `staff_u`
 confinement — if it locks out, `enable_stig=false` is the escape hatch and this
 reverts to a justified deviation; (b) reproducibility — `semanage` rebuilds the
 SELinux policy store, so confirm the verity hash is stable across two builds (and
 normalize in 2d hygiene if it drifts).
 ## Things that are NOT deviations (kept / enforced)
 - **SELinux enforcing** (`selinux --enforcing`; labels preserved into the erofs).
@@ -44,6 +117,9 @@ Posture decisions (2026-06-18, lab phase):
  everything else stays RPM-trust-only. (fapolicyd blocking that binary was the
  original kiosk-won't-start cause.)
 - **auditd** enabled; STIG audit rules applied; logs locally.
 - **USBGuard** enabled + enforcing (`block` target) with a HID/hub allowlist and
  `AuditBackend=LinuxAudit` (see #12) — blocks USB mass storage / unknown device
  classes at the console while keeping keyboard/mouse working.
 - **sshd hardening**: root login off, password & keyboard-interactive auth off,
  key-only (drop-in `50-fleet-hardening.conf`); STIG ciphers/MACs/KEX applied.
 - **No per-host state**: SSH host keys stripped at build, regenerated at first
@@ -99,5 +99,63 @@
         prompt for one — NOPASSWD is required for it to function. Documented. -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_sudo_remove_nopasswd" selected="false"/>
    <!-- ================================================================== -->
    <!-- Report triage 2026-06-19 (scan app-9f7d8d1): dispositions for the   -->
    <!-- remaining REVIEW rows. Every entry here is justified in             -->
    <!-- docs/stig-deviations.md #12.                                        -->
    <!-- ================================================================== -->
    <!-- Bucket A — covered by an existing register entry. -->
    <!-- Partitions (#1): single erofs+tmpfs root, no separate partitions. -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_encrypt_partitions" selected="false"/>
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_auditd_audispd_configure_sufficiently_large_partition" selected="false"/>
    <!-- Bootloader (#2): UKI, no GRUB. -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_grub2_password" selected="false"/>
    <!-- FIPS off (#5): crypto.fips_enabled + FIPS-validated SSH MACs. -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_sysctl_crypto_fips_enabled" selected="false"/>
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_harden_sshd_macs_openssh_conf_crypto_policy" selected="false"/>
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_harden_sshd_macs_opensshserver_conf_crypto_policy" selected="false"/>
    <!-- Firewall off for the isolated lab boot LAN (#4). -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_configured_firewalld_default_deny" selected="false"/>
    <!-- No SSSD/PKI/smartcard (#7): host is local key-only, no domain join. -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_sssd_enable_certmap" selected="false"/>
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_sssd_has_trust_anchor" selected="false"/>
    <!-- Bucket B — architecturally absent (notchecked); N/A, justified #12. -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_account_temp_expire_date" selected="false"/>
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_accounts_user_home_paths_only" selected="false"/>
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_libreswan_approved_tunnels" selected="false"/>
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_security_patches_up_to_date" selected="false"/>
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_ssh_keys_passphrase_protected" selected="false"/>
    <!-- Bucket C — decisions, justified #12. -->
    <!-- Rocky IS vendor-supported; the rule only fails because the RHEL
         datastream checks for an RHEL subscription/CPE. -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_installed_OS_is_vendor_supported" selected="false"/>
    <!-- Single DHCP-provided resolver by design (boot LAN); multi-DNS N/A. -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_network_configure_name_resolution" selected="false"/>
    <!-- KEEP user namespaces enabled — the Chromium kiosk sandbox needs them
         (this is the check-only "_no_remediation" variant). -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_sysctl_user_max_user_namespaces_no_remediation" selected="false"/>
    <!-- Authorized-local-users check doesn't know the key-only appliance
         accounts (fleetadmin, kiosk); see #10. -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_accounts_authorized_local_users" selected="false"/>
    <!-- postfix removed (no MTA needed on the appliance; audit-failure
         notification is via remote offload, not email) -> the rule that
         requires postfix installed becomes N/A. -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_package_postfix_installed" selected="false"/>
    <!-- USBGuard (decision: ENABLE with a hardware-independent allowlist).
         usbguard is already installed + the service enabled, but its policy was
         generated on the build VM, which has no real USB input — under the
         default block target a physical console keyboard/mouse would be blocked.
         SELECT the HID + hub allow rules (class-based, hardware-independent) so
         the eval of record verifies them; the provisioner writes these + the
         LinuxAudit backend before that eval. NOTE: bench-verify physical console
         input on real hardware. -->
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_usbguard_allow_hid" selected="true"/>
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_usbguard_allow_hub" selected="true"/>
    <xccdf:select idref="xccdf_org.ssgproject.content_rule_usbguard_allow_hid_and_hub" selected="true"/>
  </xccdf:Profile>
 </xccdf:Tailoring>
@@ -44,6 +44,42 @@ logger -n 127.0.0.1 -P 514 -T -t audispd "test audit record"
 ls audit-collector/logs/                 # a 127.0.0.1/ dir appears
 ```
 ## Serving-host firewall — open 514/tcp (easy to miss)
 This container uses **host networking**, so the **serving host's own firewall
 governs port 514** — Docker does *not* manage iptables for host-net containers
 (the usual "Docker bypasses the host firewall" behaviour only applies to
 *published* bridge ports, which insert rules into the `DOCKER` chain ahead of the
 host firewall). The symptom when it's closed is deceptive: the container is
 healthy, `ss -tlnp` shows `0.0.0.0:514` listening, DNS/DHCP from the same host
 work, but booted hosts sit in `SYN-SENT` and rsyslog logs `cannot connect to
 audit.fleet.lab:514 ... Connection timed out` (timed out = **dropped**, not
 refused). The logs aren't lost — the sender's `action.resumeRetryCount="-1"`
 buffers them and drains once the port opens.
 Open 514/tcp **scoped to the boot LAN** (don't expose it globally):
 ```bash
 # ufw (Debian/Ubuntu serving host):
 sudo ufw allow from 192.168.50.0/24 to any port 514 proto tcp
 sudo ufw reload && sudo ufw status numbered
 # firewalld (RHEL/Rocky serving host):
 sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=192.168.50.0/24 port port=514 protocol=tcp accept'
 sudo firewall-cmd --reload
 ```
 Verify SYNs now complete (SYN → SYN-ACK) and a sender dir appears:
 ```bash
 sudo tcpdump -ni any 'tcp port 514 and host <sender-ip>'   # SYN-ACK now returns
 ls -R audit-collector/logs/                                 # <sender-ip>/ appears within ~1 min
 ```
 > If you ever move the collector from host networking to **published ports**
 > (`514:514`), this firewall rule stops applying — published Docker ports bypass
 > ufw/firewalld and must be controlled via Docker (`DOCKER-USER` chain) instead.
 ## What's still needed (the sender — in the image)
 This container only **receives**. To make hosts actually send, the hardened