Codex Lead Engineer
84 lines
3.9 KiB
Markdown
84 lines
3.9 KiB
Markdown
# Threat Model
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## Assets
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- project instructions, decisions, results, reviews, and escalations;
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- actor-role assignments and identity bindings;
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- event ordering and audit integrity;
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- bearer credentials;
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- commit, artifact, and baseline references;
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- service/database availability.
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## Adversaries
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- an unauthenticated network client;
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- an authenticated actor exceeding their formal mandate;
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- an implementer attempting self-review or self-acceptance;
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- a compromised bearer token;
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- a malicious artifact URI or oversized request;
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- an operator or database account attempting audit-history mutation;
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- concurrent clients exploiting check/write races.
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## Implemented controls
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| Threat | MVP control |
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|---|---|
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| Identity spoofing in tool args | no actor argument; identity comes from transport |
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| Token timing comparison | SHA-256 digest and constant-time comparison |
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| Unauthorized project access | active membership lookup per call |
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| PA decision overreach | explicit decision/gate/baseline denial |
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| Product decision overreach | PO-only product decisions |
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| Self-review | reviewer role plus actor independence checks |
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| Self-acceptance | PM/PO role and result-submitter identity check |
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| Premature gate acceptance | independent APPROVE review required |
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| Double claim / TOCTOU | `BEGIN IMMEDIATE` and conditional state update |
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| Duplicate delivery | scoped request hash and idempotency record |
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| Audit update/delete | SQLite triggers reject both operations |
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| Cross-project reads | project filter plus membership resolution |
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| Browser cross-origin request | exact configurable Origin allowlist |
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| Oversized request | one MiB body limit |
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| MIME confusion/caching | strict JSON input, nosniff, no-store |
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| SQL injection | parameterized SQL; one controlled placeholder expansion |
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Artifact URIs and review evidence are recorded as untrusted data and are never
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fetched or executed by the bus.
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## Residual risks and production requirements
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1. Static bearer credentials have no built-in expiry, rotation endpoint,
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audience, issuer, or proof-of-possession. Replace the adapter with validated
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OIDC/JWT or mTLS identities.
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2. Plain HTTP is available. Use TLS and prohibit direct public access to the
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application port.
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3. SQLite append-only triggers do not protect against an operator replacing
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the entire database file or disabling triggers. Use restricted DB roles,
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PostgreSQL permissions, PITR, backups, and an external immutable audit
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export for production assurance.
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4. The event payload is not cryptographically chained or signed. Add hash
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chaining/signatures only if the agreed threat model requires tamper
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evidence against privileged database operators.
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5. No application rate limiter exists. Apply per-identity limits and request
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quotas at the trusted edge.
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6. The server emits access metadata but no security audit sink or metrics.
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Integrate structured logs, alerts, and privacy-aware retention.
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7. Membership deactivation and credential revocation are not exposed as MVP
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tools. Operators must treat compromised tokens as an immediate
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configuration/restart incident.
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8. Role assignment is one role per actor/project. Shared human/agent accounts
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undermine independence even when IDs differ and are prohibited operationally.
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9. Evidence and artifact digests are caller assertions; the bus does not
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verify repository ownership or retrieve content.
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10. Dependency-free MCP handling reduces supply-chain surface but has not yet
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been interoperability-tested against every intended client version.
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## Security verification before activation
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- run all tests and an independent code review;
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- test the exact Claude Code and ChatGPT MCP clients;
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- replace all example tokens and restrict origin/host exposure;
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- confirm backup/restore and audit export;
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- review log contents for sensitive project data;
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- add abuse limits and operational monitoring;
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- decide whether privileged-operator tamper evidence is required.
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