Attack Path Stitcher

Attack Path Stitcher

The Validation Run task (#3) produces confirmed findings per asset. Real attacker risk lives in chains: a finding on asset A leaks credentials that enable a finding on asset B that pivots into asset C. This skill builds that graph.

Mounted onto cloud-agent task #6.

Trigger

Cron daily (default 03:00 UTC). May also re-run after a Validation Run task batch completes.

Workflow

1. Load inputs.

• validated/*.json — every confirmed finding across all engagements.
• artifacts/org-surface.json — the org-wide surface graph (assets, services, network zones, trust relationships).
• findings/finding-NNN/evidence/raw-source.txt — for credential / token extraction during stitching.

1. Build asset nodes. One node per asset in org-surface.json, attributed with: tier, services, network_zone, trust_relationships.
2. Build edges — one edge per detected pivot. See reference/edge-detectors.md for the seven detectors:

• Credential reuse (creds leaked on A reused as auth on B)
• Shared secret / API key (same secret appears in two assets' evidence)
• Trust-zone transitive access (A in zone X has implicit reach to B in zone X)
• AD path hops (kerberoast / DC sync / RBCD chains)
• Cloud IAM role chains (assume-role from compromised asset)
• SSRF → internal asset reach (A's SSRF reaches B's internal endpoint)
• Supply-chain (A is a dependency of B per source-code-scanning SBOM)

1. Compute reachability closure. For each tier-crown_jewel node, BFS backwards through edges to find every external-facing node that can reach it. Mark these as "entry points".
2. Write graph to artifacts/attack-paths.json plus a human DOT file artifacts/attack-paths.dot (renderable with Graphviz).

Implementation runs through tools/chain-merger.py which handles the graph construction. The skill provides the rules the tool consults; the tool does the iteration.

Output

{OUTPUT_DIR}/
  artifacts/
    attack-paths.json     # nodes, edges, entry_points, crown_jewel_paths
    attack-paths.dot      # Graphviz source
    attack-paths.md       # ranked list of distinct paths (human read)

attack-paths.json schema:

{
  "generated_at": "2026-05-13T03:00:00Z",
  "nodes": [
    {"id": "asset42", "tier": "revenue", "services": ["http/443"], "zone": "dmz",
     "external": true, "findings": ["finding-012", "finding-018"], "max_cvss": 9.8}
  ],
  "edges": [
    {"src": "asset42", "dst": "asset77", "detector": "credential-reuse",
     "via_findings": ["finding-012", "finding-019"],
     "evidence": "credential (userpass) present in evidence of asset42 and asset77",
     "feasibility": 1.0}
  ],
  "entry_points": ["asset42", "asset05"],
  "confirmed_paths": [
    {"jewel": "asset99", "paths": [
      {"hops": ["asset42", "asset77", "asset99"],
       "edges": [{"src":"asset42","dst":"asset77","detector":"credential-reuse","feasibility":1.0,"via_findings":["finding-012"]},
                 {"src":"asset77","dst":"asset99","detector":"ssrf-reach","feasibility":1.0,"via_findings":["finding-024"]}],
       "feasibility": 1.0, "max_cvss": 9.8, "path_class": "confirmed"}
    ]}
  ],
  "inferred_paths": [
    {"jewel": "asset99", "paths": [
      {"hops": ["asset05", "asset99"], "edges": [...],
       "feasibility": 0.5, "max_cvss": 7.5, "path_class": "inferred"}
    ]}
  ],
  "truncation": {
    "edge_cap_hit": false, "depth_truncated_count": 0,
    "topn_dropped_count": 0, "max_depth": 8, "edge_cap": 50000
  }
}

Crucial for RFP §3.3 compliance: confirmed_paths contains ONLY paths where every edge has feasibility 1.0 AND every edge cites at least one validated finding. These are the "confirmed attack paths" the RFP requires. inferred_paths carries topology / supply-chain hops with no PoC evidence — surfaced for analyst review but excluded from remediation SLA buckets by risk-prioritiser.

Rules

1. Edges require evidence. An edge is only written if at least one finding's evidence corroborates the pivot. No speculative edges.
2. Bi-directional ≠ assumed. If A reaches B, do not infer B reaches A. Each direction needs its own evidence.
3. Deduplicate by `(src, dst, detector)`. Multiple findings that enable the same hop merge into one edge with via_findings listing all of them.
4. Feasibility ∈ {1.0, 0.5, 0.25}. Reliable PoC re-run = 1.0; conditional (race, timing, specific user) = 0.5; theoretical (logically follows but never demonstrated) = 0.25.
5. Limit path enumeration. For each crown-jewel, return top-10 paths per class (confirmed + inferred separately) sorted by feasibility × max_cvss / hop_count. Full graph is in attack-paths.json for downstream prioritisation.
6. Read-only. Stitcher never re-fires PoCs and never touches findings/. It only reads.
7. Bound graph size. Stop edge construction at 50,000 edges; cap path-search depth at --max-depth (default 8 hops). Emit truncation.edge_cap_hit, truncation.depth_truncated_count, and truncation.topn_dropped_count in the JSON so downstream consumers can detect silent path loss.
8. Confirmed vs inferred is non-negotiable. A path appears in confirmed_paths only if every edge has feasibility 1.0 AND every edge has a non-empty via_findings. Trust-zone-only, shared-secret-only, and supply-chain-only chains land in inferred_paths. This split is the contract that lets the RFP-§3.3 claim "confirmed attack paths" stand.
9. Schema enforcement on input. tools/chain-merger.py drops validated/{id}.json rows missing finding_id or asset, or whose verdict != "VALID", with stderr WARNs. Upstream validator must comply with the schema in projects/rfp-3.2/task-03-validation-run.md.

References

• reference/edge-detectors.md — the 7 detector rules with concrete signal patterns.
• projects/rfp-3.3/task-06-attack-path-stitcher.md — cloud-agent runtime contract.