RAT-558: Add security threat model (THREAT_MODEL.md + SECURITY.md + AGENTS.md)

AGENTS.md

@@ -31,3 +31,10 @@ consult before producing output.
 - Don't add unnecessary dependencies
 - Follow the existing codebase patterns and conventions
 - Test your solutions when possible with unit or integration tests
+
+## Security
+
+Security model: [SECURITY.md](./SECURITY.md), which links to the project's
+threat model at [THREAT_MODEL.md](./THREAT_MODEL.md). Consult the threat model
+for the project's in-scope / out-of-scope declarations and known non-findings
+before reporting security issues.

SECURITY.md

@@ -9,3 +9,11 @@ TBD
   - Configuration files and XSLT documents passed to RAT are operator-controlled configuration, not request input. Reports claiming SSRF or path traversal via these resolvers, based on the assumption that the resource name is attacker-controlled, are out of scope under the documented threat model. XML and XSLT authorship, as well as resource configuration, are privileged operations.
 
   - Applications that thread untrusted input into XML configuration or XSLT documents should validate that input before passing it to RAT. Responsibility for such validation rests with the application, not with RAT.
+
+## Threat Model
+
+The full Apache Creadur RAT threat model — scope and intended use, trust
+boundaries, the security properties RAT provides and disclaims, the adversary
+model, and known non-findings — is documented in
+[THREAT_MODEL.md](./THREAT_MODEL.md). The scope notes above are a summary;
+THREAT_MODEL.md is the detailed companion.

THREAT_MODEL.md

@@ -0,0 +1,302 @@
+<!--
+  Licensed to the Apache Software Foundation (ASF) under one or more
+  contributor license agreements.  See the NOTICE file distributed with
+  this work for additional information regarding copyright ownership.
+  The ASF licenses this file to You under the Apache License, Version 2.0
+  (the "License"); you may not use this file except in compliance with
+  the License.  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+-->
+# Apache Creadur (RAT) — Threat Model
+
+## §1 Header
+
+- **Project:** Apache Creadur — primarily **RAT (Release Audit Tool)**
+  (`apache/creadur-rat`), with sibling tools **Whisker**
+  (`apache/creadur-whisker`, license-documentation generator) and **Tentacles**
+  (`apache/creadur-tentacles`, release-bundle analyzer). This model is written
+  in `creadur-rat` and covers the Creadur dev-tool family; Whisker/Tentacles
+  share RAT's trust profile (§2).
+- **Written against:** `main`/`master` @ HEAD (2026-06).
+- **Author:** ASF Security team, via the threat-model-producer rubric (Scovetta
+  rubric) at the Creadur PMC's request (path 3).
+- **Status:** DRAFT — all §14 questions answered in the PR #677 review
+  (ottlinger, Claudenw; 2026-06-21); ready to ratify at the PMC's discretion.
+- **Reporting cross-reference:** §8-violating findings via the ASF security
+  process ([`SECURITY.md`](SECURITY.md)); §3/§9 findings closed citing this doc.
+- **Provenance legend:** *(documented)* / *(maintainer)* / *(inferred)* — each
+  *(inferred)* has a §14 open question.
+- **Draft confidence:** ~14 documented / 16 maintainer / 1 inferred (all §14
+  questions answered in the PR #677 review, 2026-06).
+
+**What it is.** RAT is a **build-time / CLI license-auditing tool**: it walks a
+source tree, matches files against configurable license/header definitions, and
+reports unapproved or unknown licenses. It runs as a **CLI**, an **Ant task**,
+or a **Maven plugin** — always **in the developer's or CI's own process**,
+never as a network service. Whisker generates license documentation; Tentacles
+inspects staged release bundles. None is a server.
+
+## §2 Scope and intended use
+
+Intended use: a project maintainer or CI job runs RAT over a codebase to verify
+license compliance before a release or on each change. The two inputs are the
+**tree being audited** (files, including archives RAT descends into) and the
+**RAT configuration** (XML/text license + matcher definitions).
+
+Caller trust level: the developer/CI invoking RAT is trusted. The **inputs are
+normally trusted too** (your own source, your own config) — but RAT is
+sometimes pointed at **untrusted input**: a CI job auditing an untrusted
+contribution/PR, or auditing a downloaded third-party artifact. That is the
+case the model cares about. *(maintainer — Claudenw, PR #677: confirmed; RAT
+config is operator-trusted, the scanned files may be untrusted.)*
+
+**Component families.**
+
+| Family | Entry point | Untrusted-input exposure | In model? |
+| --- | --- | --- | --- |
+| File walking + license matching | `Reporter`, walkers | scanned file **content/paths** | **Yes** |
+| **XML configuration reader** | `XMLConfigurationReader` | the **config** (if attacker-supplied) | **Yes** (XXE surface) |
+| **Archive walker** | `ArchiveWalker` | archives in the tree (zip/jar/tar) | **Yes** (decompression-bomb surface) |
+| CLI / Ant task / Maven plugin | wrappers | invocation args (trusted caller) | wrappers — trusted |
+| **License-header insertion (write mode)** | `--addLicense` / editors | **modifies files in the audited tree** (operator-invoked) | trusted-input (§3) |
+| Whisker / Tentacles | their CLIs | same dev-tool profile | sibling — §2 note |
+
+**Note (PMC, review).** The CLI, Ant task, and Maven plugin front-ends are
+generated from a common option core, so any security-relevant behaviour (or
+gap) in that core transfers automatically to all three UIs — a finding in one
+front-end's handling generally applies to all of them. *(maintainer.)*
+
+## §3 Out of scope (explicit non-goals)
+
+- **RAT as a security scanner.** RAT checks *license* compliance; it is **not**
+  a vulnerability scanner or a security gate. "RAT didn't catch X security
+  issue" is not in scope. *(documented — purpose.)*
+- **Audit *correctness* as a security property.** A missed/false license match
+  is a correctness bug, not a vulnerability (unless it crosses a resource bound,
+  §8). *(inferred.)*
+- **The build/CI environment** RAT runs in, and the trust of the source tree
+  when RAT is deliberately run on your own (trusted) code — the dominant,
+  intended case. Findings whose only impact requires running RAT on input you
+  already trust are `OUT-OF-MODEL: trusted-input`.
+- **Test resources** (the deliberately-odd license fixtures under
+  `*/src/test/resources/`) — those are test data, not a target.
+- **RAT's header-insertion / file-modification mode** (`--addLicense` and the
+  editors) — RAT can *write* license headers into the audited files, mutating
+  the tree. This is explicitly operator-invoked against the operator's own
+  (trusted) sources; a run that modifies files the operator already controls is
+  `OUT-OF-MODEL: trusted-input`. (Raised by the PMC in review — write mode is
+  noted here so the boundary is explicit rather than silent.) *(maintainer.)*
+- **Custom matchers / matcher extensions**
+  (<https://creadur.apache.org/rat/license_def.html#Matchers>) — RAT lets the
+  operator define custom matcher classes in its configuration, and a custom
+  matcher sees the full text of every file selected for scanning. Because the
+  matcher set is operator-defined configuration under the control of whoever
+  runs RAT (not attacker-supplied), a custom matcher reading scanned text is
+  `OUT-OF-MODEL: trusted-input` — the same posture as any operator-supplied
+  extension code (cf. the write mode above). (Raised by the PMC in review.)
+  *(maintainer — Claudenw.)*
+
+## §4 Trust boundaries and data flow
+
+The boundary is **the input RAT is pointed at** — files and configuration.
+RAT's security questions only arise when that input is **untrusted**:
+
+```
+caller invokes RAT (CLI/Ant/Maven) on a directory + a config
+   │ trusted invocation
+   ▼
+read configuration (XMLConfigurationReader) ── XXE surface if config is untrusted
+walk tree -> for each file: read content, match licenses
+   └─ ArchiveWalker descends into zip/jar/tar ── decompression-bomb / path surface if archive is untrusted
+   ▼
+report (approved / unapproved / unknown)
+```
+
+**Reachability precondition (triager's test):** a finding is in-model only if it
+is triggered by **untrusted input** (a hostile file/archive/config) that a
+*realistic* RAT deployment processes — e.g. CI auditing an untrusted PR. A
+finding that requires the operator to feed RAT input they already control is
+`OUT-OF-MODEL: trusted-input` (§3).
+
+## §5 Assumptions about the environment
+
+- A JRE; RAT reads the filesystem it is pointed at and writes a report. It opens
+  **no network connections** and runs no services — RAT runs locally and only
+  opens files. The one operator-reachable exception is an XSLT stylesheet using
+  `xsl:include` to pull a remote resource; XSLT stylesheets are trusted,
+  operator-controlled config, so that is `OUT-OF-MODEL: trusted-input` (§3).
+  (Build tooling — Maven/Ant — may fetch dependencies, but RAT itself does not.)
+  *(maintainer — Claudenw + ottlinger, PR #677.)*
+- The XML parser behaviour depends on the platform JAXP and is configurable via
+  the standard [JAXP system properties](https://docs.oracle.com/javase/8/docs/technotes/guides/security/jaxp/jaxp.html);
+  RAT disables external entities by default (§5a / §8 #2). *(maintainer —
+  Claudenw, PR #677.)*
+
+## §5a Build-time and configuration variants
+
+RAT has no security-mode flag. The security-relevant configuration is whether
+its **XML config parser disables DOCTYPE/external entities** and whether the
+**archive walker bounds decompression** (depth/size/entry count). Both are
+hardcoded behaviours, not operator knobs. The **archive walker does not bound
+decompression** — it extracts entry contents into an in-memory buffer (Apache
+Commons Compress `ArchiveStreamFactory`) with no size/depth/entry-count limit
+(§8/§9, maintainer-confirmed). The XML config reader **disables external
+entities**; DOCTYPE handling is further hardened by PR #679 (§8 #2). There is no
+"insecure default toggle". *(maintainer — Claudenw, PR #677; hardening in #679.)*
+
+## §6 Assumptions about inputs
+
+| Input | Attacker-controllable? (untrusted-run) | Concern |
+| --- | --- | --- |
+| scanned file content | **yes** | parsed/read; resource use |
+| scanned file paths / archive entry names | **yes** | reported as labels only — entries are read into memory, never extracted to disk, so no zip-slip / path-traversal-on-write surface *(maintainer)* |
+| archives (zip/jar/tar) in the tree | **yes** | decompression bomb / nested-archive depth |
+| RAT XML configuration | **maybe** (only if config is attacker-supplied) | XXE / external entity |
+| invocation arguments | no — trusted caller | — |
+
+## §7 Adversary model
+
+- **In scope:** the party who controls the files/archives/config that an
+  *untrusted-input* RAT run processes — e.g. a contributor whose PR is audited
+  by CI, or the author of a third-party artifact being audited. Capabilities:
+  craft a malicious archive (zip bomb), a hostile XML config (XXE), or
+  pathological file content. *(maintainer — Claudenw, PR #677.)*
+- **Out of scope:** an attacker who controls the RAT invocation or the trusted
+  source tree (the normal case — they already own the build).
+
+## §8 Security properties the project provides
+
+1. **Bounded resource use on untrusted archives** — **not currently provided.**
+   The archive walker (`ArchiveWalker`) uses Apache Commons Compress
+   `ArchiveStreamFactory` and extracts entry contents into an **in-memory
+   buffer** held until the document is processed, with no decompression /
+   size / depth / entry-count bound — so a crafted archive can exhaust memory
+   (OOM). This is therefore a **disclaimed gap (§9)** plus a downstream
+   responsibility (§10), not a provided property. *(maintainer — confirmed by
+   the Creadur PMC in PR #677 review, 2026-06.)*
+2. **Safe XML configuration parsing (no XXE)** — **provided.** The config reader
+   has **external entities disabled**; DOCTYPE handling is further hardened by
+   PR #679. *Violation:* file read / SSRF via a crafted config. *Severity:*
+   critical when config is untrusted. *(maintainer — Claudenw, PR #677; hardening
+   in #679.)*
+3. **No ambient network/side effects** — RAT does filesystem I/O only; it opens
+   no network connections on default settings. (Sole exception: an
+   operator-supplied XSLT `xsl:include` pointing at a remote resource — trusted
+   config, `OUT-OF-MODEL`.) *Violation:* unexpected outbound connection.
+   *(maintainer — Claudenw + ottlinger, PR #677.)*
+
+(Item 1 is a disclaimed §9 gap per the maintainer's archive answer; item 2 is a
+provided property — external entities disabled, with PR #679 hardening DOCTYPE.)
+
+## §9 Security properties the project does *not* provide
+
+- **No safety guarantee when run on fully untrusted input without sandboxing**,
+  if the §14 answers reveal the XML parser/archive walker are not hardened. In
+  that case: treat RAT-on-untrusted-input as you would any parser — sandbox it.
+- **It is not a security/vulnerability scanner** (§3); a clean RAT report says
+  nothing about security.
+- **Decompression-bomb / archive resource exhaustion** — **confirmed not
+  bounded.** Archives are extracted into an in-memory buffer with no
+  size/depth/entry-count limit (Commons Compress `ArchiveStreamFactory`), so
+  RAT pointed at untrusted archives can OOM. Runs over untrusted archives must
+  be sandboxed / resource-limited (§10). *(maintainer.)*
+- **Well-known classes (parser/archive tools):** decompression bombs /
+  nested-archive blowup remain the live untrusted-archive risk. XXE via
+  configuration is mitigated (external entities disabled, §8 #2). Path-traversal
+  on archive entries does **not** apply: RAT reads entries into memory and never
+  extracts them to disk, so an entry label like `bar/baz.zip#/junk.txt` is a
+  report string, not a write path. *(maintainer — Claudenw, PR #677.)*
+
+## §10 Downstream responsibilities
+
+- When auditing **untrusted** input (CI on untrusted PRs, third-party
+  artifacts), run RAT with resource limits / in a sandbox, and do not feed it
+  attacker-controlled **configuration**.
+- Keep RAT updated; pin the version in your build.
+- For your own (trusted) source tree — the normal case — no special handling.
+
+## §11 Known misuse patterns
+
+- **Running RAT on untrusted archives/config in CI** without resource limits,
+  expecting it to be hardened against decompression bombs / XXE.
+- **Treating a clean RAT report as a security sign-off** (it is a license check).
+
+## §11a Known non-findings (recurring false positives)
+
+- **"RAT reads/parses files it is told to scan"** on a **trusted** tree — that
+  is the function; `OUT-OF-MODEL: trusted-input` (§3/§6).
+- **Odd/invalid license fixtures under `src/test/resources/`** — test data, not
+  a target. `OUT-OF-MODEL: unsupported-component` (§3).
+- **"RAT didn't detect a security vulnerability"** — out of purpose (§3).
+- **XML parsing / archive reading flagged generically** without an untrusted-
+  input path — non-finding unless the reachability precondition (§4) is met.
+
+## §12 Conditions that would change this model
+
+- RAT gaining a network surface or a server mode.
+- A change to the XML parser hardening or archive-walker bounds (§5a/§8).
+- A report unroutable to a §13 disposition → revise §8/§9.
+
+## §13 Triage dispositions
+
+| Disposition | Meaning | Licensed by |
+| --- | --- | --- |
+| `VALID` | A §8 property breaks via untrusted input on a realistic run. | §8, §6, §7 |
+| `VALID-HARDENING` | A §11 misuse is too easy (e.g. no archive bound). | §11 |
+| `OUT-OF-MODEL: trusted-input` | Requires RAT to process input the operator already trusts. | §6 |
+| `OUT-OF-MODEL: adversary-not-in-scope` | Needs control of the RAT invocation/host. | §7 |
+| `OUT-OF-MODEL: unsupported-component` | Test fixtures / out-of-purpose. | §3 |
+| `BY-DESIGN: property-disclaimed` | "Not a security scanner", trusted-input runs. | §9 |
+| `KNOWN-NON-FINDING` | Matches §11a. | §11a |
+| `MODEL-GAP` | Unroutable. | triggers §12 |
+
+## §14 Open questions for the maintainers
+
+All wave-1/2/3 questions were answered by the Creadur PMC in the PR #677 review
+(ottlinger, Claudenw; 2026-06) and folded above. Kept here as a resolved record.
+
+- **Q1 — trust posture (answered, Claudenw).** Confirmed: RAT configuration
+  (XSLT stylesheets, config files, license definitions, custom matchers) is
+  trusted/operator-controlled; the scanned **files** may be untrusted (CI
+  auditing a third-party PR/artifact). The attack surface is whatever can break
+  out of the scanning stream under default settings. Folded into §2 / §7.
+- **Q2 — no network (answered, Claudenw + ottlinger).** Confirmed: RAT opens no
+  network connections; it only reads files. Sole exception is an operator-set
+  XSLT `xsl:include` to a remote resource (trusted config → `OUT-OF-MODEL`).
+  Build tooling (Maven/Ant) may fetch dependencies, but RAT itself does not.
+  Folded into §5 / §8 #3.
+- **Q3 — XXE / XML parser (answered, Claudenw).** External entities are
+  **disabled** in the config reader; DOCTYPE handling is further hardened by
+  PR #679. JAXP behaviour is configurable via the standard JAXP system
+  properties. §8 #2 is now a **provided** property.
+- **Q4 — archive bound (answered, PMC).** No bound — entries are read into an
+  in-memory buffer (Commons Compress) with no size/depth/entry-count limit, and
+  OOM is **not** guarded ("we probably should add a limit but at this time we do
+  not"). Resolved as a §9 gap + §10 responsibility; §8 #1 is **not** provided.
+  Entries are never extracted to disk, so there is no path-traversal-on-write
+  surface (§6 / §9).
+- **Q5 / Q6 — Whisker / Tentacles coexistence (answered, ottlinger).**
+  Development on Whisker/Tentacles is low right now; the PMC prefers to **start
+  with RAT** and add the sibling pointer files (AGENTS.md → SECURITY.md → model)
+  to `creadur-whisker` / `creadur-tentacles` later, to reduce noise. This PR is
+  therefore scoped to `creadur-rat`; the sibling chain is a deferred follow-up.
+
+With every question resolved, this model is ready to move from DRAFT to ratified
+at the PMC's discretion.
+
+## §15 Appendix — existing-policy back-map
+
+A basic `SECURITY.md` was introduced via #671 (ASF security-process pointer);
+this PR **appends** the `AGENTS.md` → `SECURITY.md` → `THREAT_MODEL.md`
+discoverability pointer to it and adds `AGENTS.md`. With every §14 question
+answered — Q4 archive walker unbounded → §9 gap, Q3 external entities disabled +
+PR #679 hardening DOCTYPE → §8 #2 provided — the §8/§9 split is settled. The same
+pointer chain will be added to `creadur-whisker` and `creadur-tentacles` as a
+deferred follow-up (§14 Q5/Q6).