boma/docs/security/accepted-risks.md

Accepted security risks

Conscious security trade-offs we are choosing to live with — recorded so "what we are not doing" is explicit and revisitable, not forgotten. This register is a living document, deliberately kept out of ADR-002 (which records durable decisions) so the ADR stays stable.

Owned by ADR-002 (Security baseline and strategy). Re-challenged during the periodic security review (planned /security-review; see docs/TODO.md).

Each entry: the risk · why we accept it (rationale) · what would make us revisit (trigger).

#	Accepted risk	Rationale	Revisit trigger
R1	Active supply-chain scanning deferred — baseline hygiene is required (tiered image pinning per ADR-011 — stateful tag@digest, stateless rolling — prefer official/verified images; gitleaks), but images and dependencies are not actively vulnerability-scanned (Trivy/Grype) or signature-verified	Scanning only pays off with the capacity to triage its output; the realistic threat is opportunistic, not a targeted supply-chain attack	A monitoring/triage stack is live; hosting high-value data/finances for others; a relevant upstream compromise
R2	SELinux not used — no SELinux mandatory access control	AppArmor — Debian-native and enforced via the CIS baseline — already provides MAC; adding SELinux means two MAC systems, non-native to Debian, for no real gain	A service that ships and requires its own SELinux policy; threat model shifts toward targeted attackers
R3	Self-hosted mesh control plane is a public target on askari — the NetBird coordinator (ADR-016) exposes a management API + dashboard (TCP 80/443) and STUN (UDP 3478) on askari's public IP; the management API controls the whole mesh (NetBird v0.72.4 embeds STUN in the combined server — no separate Coturn)	Self-hosting means no third-party trust and an off-site control plane that survives a homelab outage (boma's sovereignty ethos). Residual surface is on askari (already a public VPS) and is mitigated: TLS + embedded-IdP login, source-IP restriction where practical, base hardening, version-pinned NetBird (ADR-011) patched on boma's cadence	A coordinator compromise or unpatched NetBird CVE; the management plane is reachable without auth/IP-limits; the operational burden makes a hosted coordinator worth reconsidering
R4	No cryptographic WORM for logs — shipped logs are append-only via Loki's push API and copied off-site to askari (ADR-018), but the stored chunks are not object-locked/immutable; a root-on-askari attacker could edit history	Append-only push + off-site copy already defeats the realistic threat (a host attacker covering tracks survives even full-cluster compromise). True WORM (object-lock) is forensic-grade cost for boma's opportunistic threat model (R1)	Threat model shifts toward targeted/forensic; a regulatory/evidentiary need appears; askari itself is assessed as a likely target
R5	No disk encryption on ubongo — the control node's SSD (SanDisk X600 256 GB, TCG-Opal-capable but Opal unused) is unencrypted at rest, so it holds recovery-critical secrets in plaintext: the Ansible Vault password's rbw local cache and (future) Terraform state. Physical theft of the box would expose them	ubongo is always-on in a physically controlled location; compensating controls are a BIOS supervisor password and disabled external/USB + PXE boot (an attacker cannot trivially boot another OS to read the disk), and the offline-recoverable design means the irreducible root secret (Vaultwarden master password) is never stored on the box anyway. Full-disk encryption was weighed against the always-on/unattended-reboot requirement (LUKS+TPM auto-unlock or passphrase) and deferred for simplicity at this trust level	ubongo is relocated to a less-trusted physical location; the box starts holding additional high-value secrets; or a reinstall onto LUKS (TPM-sealed) is undertaken
R6	le-prod-wildcard integration runs — when CERTS=le-prod-wildcard is passed to make test-integration, the production Gandi PAT (vault.gandi.pat) is passed to an ephemeral local test VM via the var overlay, and transient _acme-challenge TXT records are written into the real wingu.me DNS zone to satisfy the Let's Encrypt DNS-01 challenge. A compromised or long-lived test VM could exfiltrate the PAT; the real zone is briefly (seconds) modified	Scope is on-demand only — le-staging is the default cert tier (CERTS=internal for incident repro); le-prod-wildcard is an explicit opt-in. Compensating controls: the VM is ephemeral and destroyed on success; it sits on an isolated libvirt NAT network (no LAN/mesh access); TXT records are auto-removed by Caddy immediately after validation; the PAT is not persisted inside the VM after the run. ADR-025 documents the cert-tier design and the three isolation invariants	The PAT is exfiltrated from a test VM; the wingu.me zone shows unexpected records; a CERTS=le-prod-wildcard run must be audited or the tier must be revoked
R7	claude AI-worker has NOPASSWD:ALL sudo on ubongo — the automated AI-worker account can execute any command as root on the control node without a password prompt. A compromised or misbehaving agent session could make arbitrary root-level changes to ubongo	The account is password-locked (no interactive claude login; NOPASSWD sudo is the account's only escalation path, so there is no "su to claude + sudo" attack). auditd + Loki attribution (ADR-018) logs every sudo invocation with the originating user. The drop-in (/etc/sudoers.d/claude-ai-worker) is repo-managed via base__ai_worker_user — revocable in one commit + one deploy. Single-operator homelab; all changes in git; off-machine backups (ADR-022). Full rationale: ADR-015 amendment (2026-06-18) + ADR-021 §Sudo model.	The AI-worker executes a destructive action that cannot be rolled back via git; the account key is compromised; the threat model shifts toward targeted remote attackers

Last reviewed: 2026-06-18. The prior gaps (full CIS hardening, SELinux/AppArmor, IDS) were re-challenged and adopted rather than accepted: CIS Debian L1+L2 + CIS Docker, AppArmor (enforce), AIDE file-integrity, and Suricata network IDS are now part of the security strategy (ADR-002). See STATUS.md / docs/TODO.md for build status. As CIS is implemented, any specific item that proves impractical is added here as a named exception.