# ARCHIVED ADVISORY

> **Status:** Archived
> **Archived Date:** 2025-12-18
> **Implementation Sprints:**
> - `SPRINT_3700_0001_0001_witness_foundation.md` - BLAKE3 + Witness Schema
> - `SPRINT_3700_0002_0001_vuln_surfaces_core.md` - Vuln Surface Builder
> - `SPRINT_3700_0003_0001_trigger_extraction.md` - Trigger Method Extraction
> - `SPRINT_3700_0004_0001_reachability_integration.md` - Reachability Integration
> - `SPRINT_3700_0005_0001_witness_ui_cli.md` - Witness UI/CLI
> - `SPRINT_3700_0006_0001_incremental_cache.md` - Incremental Cache
>
> **Gap Analysis:** See `C:\Users\vlindos\.claude\plans\lexical-knitting-map.md`

---

Here's a compact, practical way to add two high-leverage capabilities to your scanner: **DSSE-signed path witnesses** and **Smart-Diff x Reachability**-what they are, why they matter, and exactly how to implement them in Stella Ops without ceremony.

---

# 1) DSSE-signed path witnesses (entrypoint -> calls -> sink)

**What it is (in plain terms):**
When you flag a CVE as "reachable," also emit a tiny, human-readable proof: the **exact path** from a real entrypoint (e.g., HTTP route, CLI verb, cron) through functions/methods to the **vulnerable sink**. Wrap that proof in a **DSSE** envelope and sign it. Anyone can verify the witness later-offline-without rerunning analysis.

**Why it matters:**

* Turns red flags into **auditable evidence** (quiet-by-design).
* Lets CI/CD, auditors, and customers **verify** findings independently.
* Enables **deterministic replay** and provenance chains (ties nicely to in-toto/SLSA).

**Minimal JSON witness (stable, vendor-neutral):**

```json
{
  "witness_schema": "stellaops.witness.v1",
  "artifact": { "sbom_digest": "sha256:...", "component_purl": "pkg:nuget/Example@1.2.3" },
  "vuln": { "id": "CVE-2024-XXXX", "source": "NVD", "range": "<=1.2.3" },
  "entrypoint": { "kind": "http", "name": "GET /billing/pay" },
  "path": [
    {"symbol": "BillingController.Pay()", "file": "BillingController.cs", "line": 42},
    {"symbol": "PaymentsService.Authorize()", "file": "PaymentsService.cs", "line": 88},
    {"symbol": "LibXYZ.Parser.Parse()", "file": "Parser.cs", "line": 17}
  ],
  "sink": { "symbol": "LibXYZ.Parser.Parse()", "type": "deserialization" },
  "evidence": {
    "callgraph_digest": "sha256:...",
    "build_id": "dotnet:RID:linux-x64:sha256:...",
    "analysis_config_digest": "sha256:..."
  },
  "observed_at": "2025-12-18T00:00:00Z"
}
```

**Wrap in DSSE (payloadType & payload are required)**

```json
{
  "payloadType": "application/vnd.stellaops.witness+json",
  "payload": "base64(JSON_above)",
  "signatures": [{ "keyid": "attestor-stellaops-ed25519", "sig": "base64(...)" }]
}
```

**.NET 10 signing/verifying (Ed25519)**

```csharp
using System.Security.Cryptography;
using System.Text.Json;

var payloadBytes = JsonSerializer.SerializeToUtf8Bytes(witnessJsonObj);
var dsse = new {
  payloadType = "application/vnd.stellaops.witness+json",
  payload = Convert.ToBase64String(payloadBytes),
  signatures = new [] { new { keyid = keyId, sig = Convert.ToBase64String(Sign(payloadBytes, privateKey)) } }
};
byte[] Sign(byte[] data, byte[] privateKey)
{
    using var ed = new Ed25519();
    // import private key, sign data (left as your Ed25519 helper)
    return ed.SignData(data, privateKey);
}
```

**Where to emit:**

* **Scanner.Worker**: after reachability confirms `reachable=true`, emit witness -> **Attestor** signs -> **Authority** stores (Postgres) -> optional Rekor-style mirror.
* Expose `/witness/{findingId}` for download & independent verification.

---

# 2) Smart-Diff x Reachability (incremental, low-noise updates)

**What it is:**
On **SBOM/VEX/dependency** deltas, don't rescan everything. Update only **affected regions** of the call graph and recompute reachability **just for changed nodes/edges**.

**Why it matters:**

* **Order-of-magnitude faster** incremental scans.
* Fewer flaky diffs; triage stays focused on **meaningful risk change**.
* Perfect for PR gating: "what changed" -> "what became reachable/unreachable."

**Core idea (graph-reachability):**

* Maintain a per-service **call graph** `G = (V, E)` with **entrypoint set** `S`.
* On diff: compute changed nodes/edges DV/DE.
* Run **incremental BFS/DFS** from impacted nodes to sinks (forward or backward), reusing memoized results.
* Recompute only **frontiers** touched by D.

**Minimal tables (Postgres):**

```sql
-- Nodes (functions/methods)
CREATE TABLE cg_nodes(
  id BIGSERIAL PRIMARY KEY,
  service TEXT, symbol TEXT, file TEXT, line INT,
  hash TEXT, UNIQUE(service, hash)
);
-- Edges (calls)
CREATE TABLE cg_edges(
  src BIGINT REFERENCES cg_nodes(id),
  dst BIGINT REFERENCES cg_nodes(id),
  kind TEXT, PRIMARY KEY(src, dst)
);
-- Entrypoints & Sinks
CREATE TABLE cg_entrypoints(node_id BIGINT REFERENCES cg_nodes(id) PRIMARY KEY);
CREATE TABLE cg_sinks(node_id BIGINT REFERENCES cg_nodes(id) PRIMARY KEY, sink_type TEXT);

-- Memoized reachability cache
CREATE TABLE cg_reach_cache(
  entry_id BIGINT, sink_id BIGINT,
  path JSONB, reachable BOOLEAN,
  updated_at TIMESTAMPTZ,
  PRIMARY KEY(entry_id, sink_id)
);
```

**Incremental algorithm (pseudocode):**

```text
Input: DSBOM, DDeps, DCode -> DNodes, DEdges
1) Apply D to cg_nodes/cg_edges
2) ImpactSet = neighbors(DNodes U endpoints(DEdges))
3) For each e in Entrypoints intersect ancestors(ImpactSet):
     Recompute forward search to affected sinks, stop early on unchanged subgraphs
     Update cg_reach_cache; if state flips, emit new/updated DSSE witness
```

**.NET 10 reachability sketch (fast & local):**

```csharp
HashSet<int> ImpactSet = ComputeImpact(deltaNodes, deltaEdges);
foreach (var e in Intersect(Entrypoints, Ancestors(ImpactSet)))
{
    var res = BoundedReach(e, affectedSinks, graph, cache);
    foreach (var r in res.Changed)
    {
        cache.Upsert(e, r.Sink, r.Path, r.Reachable);
        if (r.Reachable) EmitDsseWitness(e, r.Sink, r.Path);
    }
}
```

**CI/PR flow:**

1. Build -> SBOM diff -> Dependency diff -> Call-graph delta.
2. Run incremental reachability.
3. If any `unreachable->reachable` transitions: **fail gate**, attach DSSE witnesses.
4. If `reachable->unreachable`: auto-close prior findings (and archive prior witness).

---

# UX hooks (quick wins)

* In findings list, add a **"Show Witness"** button -> modal renders the signed path (entrypoint->...->sink) + **"Verify Signature"** one-click.
* In PR checks, summarize only **state flips** with tiny links: "+2 reachable (view witness)" / "-1 (now unreachable)".

---

# Minimal tasks to get this live

* **Scanner.Worker**: build call-graph extraction (per language), add incremental graph store, reachability cache.
* **Attestor**: DSSE signing endpoint + key management (Ed25519 by default; PQC mode later).
* **Authority**: tables above + witness storage + retrieval API.
* **Router/CI plugin**: PR annotation with **state flips** and links to witnesses.
* **UI**: witness modal + signature verify.

If you want, I can draft the exact Postgres migrations, the C# repositories, and a tiny verifier CLI that checks DSSE signatures and prints the call path.
Below is a concrete, buildable blueprint for an **advanced reachability analysis engine** inside Stella Ops. I'm going to assume your "Stella Ops" components are roughly:

* **Scanner.Worker**: runs analyses in CI / on artifacts
* **Authority**: stores graphs/findings/witnesses
* **Attestor**: signs DSSE envelopes (Ed25519)
* (optional) **SurfaceBuilder**: background worker that computes "vuln surfaces" for packages

The key advance is: **don't treat a CVE as "a package"**. Treat it as a **set of trigger methods** (public API) that can reach the vulnerable code inside the dependency-computed by "Smart-Diff" once, reused everywhere.

---

## 0) Define the contract (precision/soundness) up front

If you don't write this down, you'll fight false positives/negatives forever.

### What Stella Ops will guarantee (first release)

* **Whole-program static call graph** (app + selected dependency assemblies)
* **Context-insensitive** (fast), **path witness** extracted (shortest path)
* **Dynamic dispatch handled** with CHA/RTA (+ DI hints), with explicit uncertainty flags
* **Reflection handled best-effort** (constant-string resolution), otherwise "unknown edge"

### What it will NOT guarantee (first release)

* Perfect handling of reflection / `dynamic` / runtime codegen
* Perfect delegate/event resolution across complex flows
* Full taint/dataflow reachability (you can add later)

This is fine. The major value is: "**we can show you the call path**" and "**we can prove the vuln is triggered by calling these library APIs**".

---

## 1) The big idea: "Vuln surfaces" (Smart-Diff -> triggers)

### Problem

CVE feeds typically say "package X version range Y is vulnerable" but rarely say *which methods*. If you only do package-level reachability, noise is huge.

### Solution

For each CVE+package, compute a **vulnerability surface**:

* **Candidate sinks** = methods changed between vulnerable and fixed versions (diff at IL level)
* **Trigger methods** = *public/exported* methods in the vulnerable version that can reach those changed methods internally

Then your service scan becomes:

> "Can any entrypoint reach any trigger method?"

This is both faster and more precise.

---

## 2) Data model (Authority / Postgres)

You already had call graph tables; here's a concrete schema that supports:

* graph snapshots
* incremental updates
* vuln surfaces
* reachability cache
* DSSE witnesses

### 2.1 Graph tables

```sql
CREATE TABLE cg_snapshots (
  snapshot_id BIGSERIAL PRIMARY KEY,
  service TEXT NOT NULL,
  build_id TEXT NOT NULL,
  graph_digest TEXT NOT NULL,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  UNIQUE(service, build_id)
);

CREATE TABLE cg_nodes (
  node_id BIGSERIAL PRIMARY KEY,
  snapshot_id BIGINT REFERENCES cg_snapshots(snapshot_id) ON DELETE CASCADE,
  method_key TEXT NOT NULL,              -- stable key (see below)
  asm_name TEXT,
  type_name TEXT,
  method_name TEXT,
  file_path TEXT,
  line_start INT,
  il_hash TEXT,                          -- normalized IL hash for diffing
  flags INT NOT NULL DEFAULT 0,          -- bitflags: has_reflection, compiler_generated, etc.
  UNIQUE(snapshot_id, method_key)
);

CREATE TABLE cg_edges (
  snapshot_id BIGINT REFERENCES cg_snapshots(snapshot_id) ON DELETE CASCADE,
  src_node_id BIGINT REFERENCES cg_nodes(node_id) ON DELETE CASCADE,
  dst_node_id BIGINT REFERENCES cg_nodes(node_id) ON DELETE CASCADE,
  kind SMALLINT NOT NULL,                -- 0=call,1=newobj,2=dispatch,3=delegate,4=reflection_guess,...
  PRIMARY KEY(snapshot_id, src_node_id, dst_node_id, kind)
);

CREATE TABLE cg_entrypoints (
  snapshot_id BIGINT REFERENCES cg_snapshots(snapshot_id) ON DELETE CASCADE,
  node_id BIGINT REFERENCES cg_nodes(node_id) ON DELETE CASCADE,
  kind TEXT NOT NULL,                    -- http, grpc, cli, job, etc.
  name TEXT NOT NULL,                    -- GET /foo, "Main", etc.
  PRIMARY KEY(snapshot_id, node_id, kind, name)
);
```

### 2.2 Vuln surface tables (Smart-Diff artifacts)

```sql
CREATE TABLE vuln_surfaces (
  surface_id BIGSERIAL PRIMARY KEY,
  ecosystem TEXT NOT NULL,               -- nuget
  package TEXT NOT NULL,
  cve_id TEXT NOT NULL,
  vuln_version TEXT NOT NULL,            -- a representative vulnerable version
  fixed_version TEXT NOT NULL,
  surface_digest TEXT NOT NULL,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  UNIQUE(ecosystem, package, cve_id, vuln_version, fixed_version)
);

CREATE TABLE vuln_surface_sinks (
  surface_id BIGINT REFERENCES vuln_surfaces(surface_id) ON DELETE CASCADE,
  sink_method_key TEXT NOT NULL,
  reason TEXT NOT NULL,                  -- changed|added|removed|heuristic
  PRIMARY KEY(surface_id, sink_method_key)
);

CREATE TABLE vuln_surface_triggers (
  surface_id BIGINT REFERENCES vuln_surfaces(surface_id) ON DELETE CASCADE,
  trigger_method_key TEXT NOT NULL,
  sink_method_key TEXT NOT NULL,
  internal_path JSONB,                   -- optional: library internal witness path
  PRIMARY KEY(surface_id, trigger_method_key, sink_method_key)
);
```

### 2.3 Reachability cache & witnesses

```sql
CREATE TABLE reach_findings (
  finding_id BIGSERIAL PRIMARY KEY,
  snapshot_id BIGINT REFERENCES cg_snapshots(snapshot_id) ON DELETE CASCADE,
  cve_id TEXT NOT NULL,
  ecosystem TEXT NOT NULL,
  package TEXT NOT NULL,
  package_version TEXT NOT NULL,
  reachable BOOLEAN NOT NULL,
  reachable_entrypoints INT NOT NULL DEFAULT 0,
  updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  UNIQUE(snapshot_id, cve_id, package, package_version)
);

CREATE TABLE reach_witnesses (
  witness_id BIGSERIAL PRIMARY KEY,
  finding_id BIGINT REFERENCES reach_findings(finding_id) ON DELETE CASCADE,
  entry_node_id BIGINT REFERENCES cg_nodes(node_id),
  dsse_envelope JSONB NOT NULL,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now()
);
```

---

## 3) Stable identity: MethodKey + IL hash

### 3.1 MethodKey (must be stable across builds)

Use a normalized string like:

```
{AssemblyName}|{DeclaringTypeFullName}|{MethodName}`{GenericArity}({ParamType1},{ParamType2},...)
```

Examples:

* `MyApp|BillingController|Pay(System.String)`
* `LibXYZ|LibXYZ.Parser|Parse(System.ReadOnlySpan<System.Byte>)`

### 3.2 Normalized IL hash (for smart-diff + incremental graph updates)

Raw IL bytes aren't stable (metadata tokens change). Normalize:

* opcode names
* branch targets by *instruction index*, not offset
* method operands by **resolved MethodKey**
* string operands by literal or hashed literal
* type operands by full name

Then hash `SHA256(normalized_bytes)`.

---

*[Remainder of advisory truncated for brevity - see original file for full content]*

---

## 12) What to implement first (in the order that produces value fastest)

### Week 1-2 scope (realistic, shippable)

1. Cecil call graph extraction (direct calls)
2. MVC + Minimal API entrypoints
3. Reverse BFS reachability with path witnesses
4. DSSE witness signing + storage
5. SurfaceBuilder v1:

   * IL hash per method
   * changed methods as sinks
   * triggers via internal reverse BFS
6. UI: "Show Witness" + "Verify Signature"

### Next increment (precision upgrades)

7. async/await mapping to original methods
8. RTA + DI registration hints
9. delegate tracking for Minimal API handlers (if not already)
10. interface override triggers in surface builder

### Later (if you want "attackability", not just "reachability")

11. taint/dataflow for top sink classes (deserialization, path traversal, SQL, command exec)
12. sanitizer modeling & parameter constraints

---

## 13) Common failure modes and how to harden

### MethodKey mismatches (surface vs app call)

* Ensure both are generated from the same normalization rules
* For generic methods, prefer **definition** keys (strip instantiation)
* Store both "exact" and "erased generic" variants if needed

### Multi-target frameworks

* SurfaceBuilder: compute triggers for each TFM, union them
* App scan: choose TFM closest to build RID, but allow fallback to union

### Huge graphs

* Drop `System.*` nodes/edges unless:

  * the vuln is in System.* (rare, but handle separately)
* Deduplicate nodes by MethodKey across assemblies where safe
* Use CSR arrays + pooled queues

### Reflection heavy projects

* Mark analysis confidence lower
* Include "unknown edges present" in finding metadata
* Still produce a witness path up to the reflective callsite

---

If you want, I can also paste a **complete Cecil-based CallGraphBuilder class** (nodes+edges+PDB lines), plus the **SurfaceBuilder** that downloads NuGet packages and generates `vuln_surface_triggers` end-to-end.