RustFS Security Advisory Lessons

Use this skill as a RustFS-specific security lens before changing or approving code. For the current advisory snapshot and full pattern map, read advisory-patterns.md.

When currentness matters, refresh the advisory inventory first:

gh api repos/rustfs/rustfs/security-advisories --paginate \
  --jq '.[] | {ghsa_id,state,severity,summary,updated_at,html_url}'

For the full pattern map, read advisory-patterns.md.

Workflow

1. Scope the change

• Identify touched routes, handlers, storage paths, credentials, logs, browser surfaces, CI/release code, and policy checks.
• Treat these paths as security-sensitive by default: rustfs/src/admin/, rustfs/src/storage/, rustfs/src/auth.rs, rustfs/src/server/layer.rs, crates/iam/, crates/policy/, crates/credentials/, crates/ecstore/src/rpc/, crates/rio/, and console preview/auth code.

2. Map to advisory classes

• Read advisory-patterns.md for matching GHSA lessons.
• Do not rely on advisory titles alone. Confirm whether the issue is authentication, authorization, input validation, storage invariant, browser isolation, logging, or operational hardening.

3. Verify fail-closed behavior

• Check that unauthenticated, wrong-permission, cross-user, cross-bucket, malformed-input, and default-config cases fail explicitly.
• Prefer exact action/permission checks over broad helper calls or inferred ownership.
• Confirm lower storage/RPC layers do not bypass checks done in upper layers.

4. Require regression evidence

• For behavior changes, add focused negative tests that reproduce the advisory class.
• For sensitive fixes, include tests for the bypass form, not only the happy path.
• If a test is impractical, explain the residual risk and provide a manual verification command.

5. Report clearly

• Lead with concrete findings and file/line evidence.
• Separate proven vulnerabilities from hardening risks.
• Avoid exaggerating unauthenticated impact when the code actually rejects unauthenticated requests but allows a low-privileged authenticated bypass.

Advisory-Derived Guardrails

Auth and admin authorization

• Every admin or diagnostic route needs an explicit authn and authz story. Route registration, router whitelist, and handler-level authorization must agree.
• Match the admin action to the operation exactly. Copy-paste action constants are a known RustFS vulnerability class.
• Avoid authentication-only helpers for state-changing admin APIs; use validate_admin_request or the established equivalent with the right AdminAction.
• Do not assume admin-action Resource scoping constrains blast radius unless the policy engine actually enforces resources for that action.

IAM and service accounts

• Treat imported IAM payload fields as attacker-controlled: parent, claims, accessKey, secretKey, status, policy names, and groups.
• For service account create/update/import, prove parent ownership or root/admin authority before writing credentials or claims.
• Do not let deny_only or "no explicit deny" become an allow decision that skips required allow checks.
• Test cross-user list/update/import flows with wrong, correct, self, parent, and root identities.

S3 copy, multipart, and presigned POST

• Multipart copy must enforce source GetObject and destination PutObject semantics equivalent to CopyObject, including copy-source and policy conditions.
• Do not let CreateMultipartUpload, UploadPartCopy, CompleteMultipartUpload, or AbortMultipartUpload return success without authorization.
• Presigned POST policies are server-side contracts. Enforce content-length-range, key prefix, exact metadata/content-type, and all signed policy conditions.

Paths, object keys, and filesystem access

• Never join untrusted bucket/object/RPC path strings onto filesystem roots without normalization and boundary checks.
• Reject or safely handle .., absolute paths, URL-encoded traversal, platform separators, empty components, and paths that canonicalize outside the intended root.
• Validate both S3 object-key paths and internode/RPC disk paths; storage helpers can bypass S3 authorization if they trust already-parsed paths.

Secrets, default credentials, and crypto

• Do not ship hard-coded shared tokens, HMAC secrets, private keys, or production test keys.
• Defaults for internode/RPC auth must fail closed for network-reachable deployments or require explicit opt-in with loud warnings.
• License or token validation must use signatures with embedded public/verifying keys only; do not use private-key decryption as authenticity.
• Plan key rotation and key IDs when removing exposed keys.

Logging and debug output

• Logs must never include access keys beyond safe identifiers, secret keys, session tokens, JWT claims, HMAC secrets, expected signatures, license secrets, or raw response bodies containing credentials.
• Treat Debug implementations, ?value tracing, merged config dumps, and dependency-level HTTP body logging as leak surfaces.
• Add log-capture tests or targeted unit tests for redaction wrappers when changing credential structs or response bodies.

RPC, parsing, and panic safety

• Treat all RPC payload bytes as attacker-controlled. Replace unwrap, expect, and panic-prone deserialization with typed errors.
• Malformed request tests should cover empty bytes, truncated MessagePack/protobuf, invalid enum values, stale timestamps, and invalid signatures.
• RPC authentication must be independently strong; do not depend on S3 admin credentials unless the fallback is explicit and safe.

Browser, CORS, and console surfaces

• Do not reflect arbitrary Origin while also allowing credentials. Default CORS should be no CORS unless explicitly configured.
• Do not render user-controlled object content in a same-origin iframe with console credentials available to JavaScript.
• Prefer origin separation for object preview/download, nosniff, CSP, strict content-type handling, and avoiding durable credentials in localStorage.
• License/version-like metadata endpoints should expose only coarse public data unless authenticated.

Profiling, debug, and health endpoints

• Profiling and debug endpoints are not health checks. They require admin auth, opt-in enablement, rate limiting, and safe responses.
• Do not return absolute filesystem paths or other deployment layout in unauthenticated or low-privilege responses.
• Ensure health endpoint allowlists cannot accidentally include expensive diagnostics.

Trusted proxy and network identity

• Only honor X-Forwarded-For or X-Real-IP when the request came from a configured trusted proxy.
• Direct clients must use the socket peer address for aws:SourceIp and policy condition evaluation.
• Add tests for direct spoofed headers and trusted-proxy headers.

SSE and storage invariants

• Encryption metadata is not proof that bytes were encrypted on disk.
• When touching reader/writer wrappers such as hashing, encryption, compression, or warp readers, verify wrapper order and inspect stored bytes in regression tests.
• Avoid helper shortcuts that unwrap nested readers and accidentally bypass encryption or integrity layers.

Review Prompts

Use these prompts while reviewing a diff:

• Could a low-privileged authenticated user reach this path with the wrong action, parent, bucket, or source object?
• Does a public/default/empty config change security behavior from fail-closed to fail-open?
• Is any attacker-controlled value later used as a path, policy condition, credential identity, log field, URL, Origin, or response body?
• Is the same operation implemented in multiple paths, such as CopyObject vs UploadPartCopy, and do all paths enforce the same security contract?
• Does the test prove the exploit form is denied, or only that the intended form still works?