Merge pull request #587 from HKUDS/fix/whatsapp-bridge-security

fix(security): bind WhatsApp bridge to localhost + optional token auth

SECURITY.md

@@ -95,8 +95,8 @@ File operations have path traversal protection, but:
 - Consider using a firewall to restrict outbound connections if needed
 
 **WhatsApp Bridge:**
-- The bridge runs on `localhost:3001` by default
+- The bridge binds to `127.0.0.1:3001` (localhost only, not accessible from external network)
-- If exposing to network, use proper authentication and TLS
+- Set `bridgeToken` in config to enable shared-secret authentication between Python and Node.js
 - Keep authentication data in `~/.nanobot/whatsapp-auth` secure (mode 0700)
 
 ### 6. Dependency Security
@@ -224,7 +224,7 @@ If you suspect a security breach:
 ✅ **Secure Communication**
 - HTTPS for all external API calls
 - TLS for Telegram API
-- WebSocket security for WhatsApp bridge
+- WhatsApp bridge: localhost-only binding + optional token auth
 
 ## Known Limitations
 

bridge/src/index.ts

@@ -25,11 +25,12 @@ import { join } from 'path';
 
 const PORT = parseInt(process.env.BRIDGE_PORT || '3001', 10);
 const AUTH_DIR = process.env.AUTH_DIR || join(homedir(), '.nanobot', 'whatsapp-auth');
+const TOKEN = process.env.BRIDGE_TOKEN || undefined;
 
 console.log('🐈 nanobot WhatsApp Bridge');
 console.log('========================\n');
 
-const server = new BridgeServer(PORT, AUTH_DIR);
+const server = new BridgeServer(PORT, AUTH_DIR, TOKEN);
 
 // Handle graceful shutdown
 process.on('SIGINT', async () => {

bridge/src/server.ts

@@ -1,5 +1,6 @@
 /**
  * WebSocket server for Python-Node.js bridge communication.
+ * Security: binds to 127.0.0.1 only; optional BRIDGE_TOKEN auth.
  */
 
 import { WebSocketServer, WebSocket } from 'ws';
@@ -21,12 +22,13 @@ export class BridgeServer {
   private wa: WhatsAppClient | null = null;
   private clients: Set<WebSocket> = new Set();
 
-  constructor(private port: number, private authDir: string) {}
+  constructor(private port: number, private authDir: string, private token?: string) {}
 
   async start(): Promise<void> {
-    // Create WebSocket server
+    // Bind to localhost only — never expose to external network
-    this.wss = new WebSocketServer({ port: this.port });
+    this.wss = new WebSocketServer({ host: '127.0.0.1', port: this.port });
-    console.log(`🌉 Bridge server listening on ws://localhost:${this.port}`);
+    console.log(`🌉 Bridge server listening on ws://127.0.0.1:${this.port}`);
+    if (this.token) console.log('🔒 Token authentication enabled');
 
     // Initialize WhatsApp client
     this.wa = new WhatsAppClient({
@@ -38,7 +40,34 @@ export class BridgeServer {
 
     // Handle WebSocket connections
     this.wss.on('connection', (ws) => {
+      if (this.token) {
+        // Require auth handshake as first message
+        const timeout = setTimeout(() => ws.close(4001, 'Auth timeout'), 5000);
+        ws.once('message', (data) => {
+          clearTimeout(timeout);
+          try {
+            const msg = JSON.parse(data.toString());
+            if (msg.type === 'auth' && msg.token === this.token) {
+              console.log('🔗 Python client authenticated');
+              this.setupClient(ws);
+            } else {
+              ws.close(4003, 'Invalid token');
+            }
+          } catch {
+            ws.close(4003, 'Invalid auth message');
+          }
+        });
+      } else {
         console.log('🔗 Python client connected');
+        this.setupClient(ws);
+      }
+    });
+
+    // Connect to WhatsApp
+    await this.wa.connect();
+  }
+
+  private setupClient(ws: WebSocket): void {
     this.clients.add(ws);
 
     ws.on('message', async (data) => {
@@ -61,10 +90,6 @@ export class BridgeServer {
       console.error('WebSocket error:', error);
       this.clients.delete(ws);
     });
-    });
-
-    // Connect to WhatsApp
-    await this.wa.connect();
   }
 
   private async handleCommand(cmd: SendCommand): Promise<void> {

nanobot/channels/whatsapp.py

@@ -42,6 +42,9 @@ class WhatsAppChannel(BaseChannel):
             try:
                 async with websockets.connect(bridge_url) as ws:
                     self._ws = ws
+                    # Send auth token if configured
+                    if self.config.bridge_token:
+                        await ws.send(json.dumps({"type": "auth", "token": self.config.bridge_token}))
                     self._connected = True
                     logger.info("Connected to WhatsApp bridge")
                     

nanobot/cli/commands.py

@@ -636,14 +636,20 @@ def _get_bridge_dir() -> Path:
 def channels_login():
     """Link device via QR code."""
     import subprocess
+    from nanobot.config.loader import load_config
     
+    config = load_config()
     bridge_dir = _get_bridge_dir()
     
     console.print(f"{__logo__} Starting bridge...")
     console.print("Scan the QR code to connect.\n")
     
+    env = {**os.environ}
+    if config.channels.whatsapp.bridge_token:
+        env["BRIDGE_TOKEN"] = config.channels.whatsapp.bridge_token
+    
     try:
-        subprocess.run(["npm", "start"], cwd=bridge_dir, check=True)
+        subprocess.run(["npm", "start"], cwd=bridge_dir, check=True, env=env)
     except subprocess.CalledProcessError as e:
         console.print(f"[red]Bridge failed: {e}[/red]")
     except FileNotFoundError:

nanobot/config/schema.py

@@ -9,6 +9,7 @@ class WhatsAppConfig(BaseModel):
     """WhatsApp channel configuration."""
     enabled: bool = False
     bridge_url: str = "ws://localhost:3001"
+    bridge_token: str = ""  # Shared token for bridge auth (optional, recommended)
     allow_from: list[str] = Field(default_factory=list)  # Allowed phone numbers