Phase 5: Security Hardening Fixes - Response to Test Results

Date: January 29, 2026 Author: Claude Code Agent In Response To: Cowork Browser Agent Test Results Session: 73.12

Summary of Fixes Applied

Based on the brutally honest feedback from the Cowork Browser Agent's test results, the following fixes have been implemented:

Detailed Fixes

Fix 1: Rate Limiting Integration (Bug #2)

Files Modified:

• libs/libs-ux/embeddable-bridge/src/lib/services/host-adapter.service.ts
• libs/libs-ux/embeddable-bridge/src/lib/services/embedded-adapter.service.ts

What Was Added:

// In handleMessage() - BEFORE processing any message:
const rateLimitResult = checkRateLimit(
  this.rateLimitCounters,
  `${origin}:${message.type}`,
  rateLimitConfig
);

if (rateLimitResult.limited) {
  if (rateLimitResult.action === 'block') {
    this.log(`Rate limit exceeded - blocking message: ${message.type}`, 'warn', {
      currentCount: rateLimitResult.currentCount,
      maxRequests: rateLimitResult.maxRequests,
      resetIn: rateLimitResult.resetIn,
    });
    return; // Don't process the message
  } else if (rateLimitResult.action === 'warn') {
    this.log(`Rate limit warning (${rateLimitResult.currentCount}/${rateLimitResult.maxRequests}): ${message.type}`, 'warn');
  }
}

Default Configuration:

• maxRequests: 100 per 10 seconds
• onExceeded: 'warn' (logs warning at 80%, doesn't block by default)
• Configurable via HostAdapterConfig.rateLimit

Fix 2: UI Log Sanitization (Bug #1)

File Modified:

• apps/gograb-space/src/app/components/demos/ai-iframe-test/ai-iframe-test.component.ts

What Was Added:

// Import added:
import { sanitizeForLogging } from '@libs-ux/embeddable-bridge';

// In addLog() method:
private addLog(direction: 'in' | 'out', type: string, payload?: unknown): void {
  // Phase 5: Sanitize payload before displaying in UI to prevent token leakage
  const sanitizedPayload = payload ? sanitizeForLogging(payload) : undefined;

  this.messageLogs.update(logs => [
    {
      // ... other fields
      payload: sanitizedPayload  // Now sanitized!
    },
    ...logs
  ]);
}

Result: Auth tokens in the Message Log UI will now show as [REDACTED] instead of the actual token value.

Fix 3: Payload Validation Integration (Bug #4)

Files Modified:

• libs/libs-ux/embeddable-bridge/src/lib/services/host-adapter.service.ts
• libs/libs-ux/embeddable-bridge/src/lib/services/embedded-adapter.service.ts

What Was Added:

// In handleMessage() - AFTER rate limiting, BEFORE processing:
if (!validateMessagePayload(message.type as BridgeMessageType, message.payload)) {
  this.log(`Payload validation failed for message type: ${message.type}`, 'warn', {
    reason: 'Schema validation failed',
  });
  return; // Don't process invalid payload
}

Validators Now Active:

• AI_AUTH_INIT - validates accessToken is non-empty string
• AI_AUTH_REFRESH - validates accessToken is non-empty string
• AI_DRAG_START - validates id, type, title, sourceRect, mouseOffset

Fix 4: Debug Logging for Origin Verification

Files Modified:

• libs/libs-ux/embeddable-bridge/src/lib/services/host-adapter.service.ts
• libs/libs-ux/embeddable-bridge/src/lib/services/embedded-adapter.service.ts

What Was Added:

// In send() method - now logs targetOrigin:
this.log(`Sent message: ${type} -> targetOrigin: ${origin} (instanceId: ...)`, 'info', payload);

// In broadcast() method:
this.log(`Broadcast message: ${type} -> targetOrigin: ${origin}`, 'info', payload);

Result: With debug: true, console will now show the exact targetOrigin being used for each postMessage call, allowing verification that wildcards are not used.

Addressing Cowork Agent's Concerns

Instance ID Validation (Bug #3)

The cowork agent reported that instance ID validation wasn't working. After review:

Finding: The validation IS in place in isValidMessage() (message-protocol.ts lines 324-330):

if (msg['instanceId'] !== undefined && !isValidInstanceId(msg['instanceId'] as string)) {
  if (typeof console !== 'undefined') {
    console.warn(`[Embeddable Bridge] Rejected invalid instanceId format`);
  }
  return false;
}

Possible Reasons for Test Failure:

1. Messages sent via window.postMessage() in the host's console are received by the host's own listener, which already passed isValidMessage (same-origin messages)
2. The embedded app's listener might not have been the target
3. Console warnings might have been buried in other output

Enhancement Made: Added more verbose logging throughout to help with debugging.

Self-Origin Messages

The cowork agent noted "Self-Origin Bypass" as a concern. This is by design for same-origin:

// In isAllowedOrigin():
if (typeof window !== 'undefined' && origin === window.location.origin) {
  return true;
}

However, isValidMessage() still validates message type and instanceId format regardless of origin.

New Imports Added

host-adapter.service.ts

import {
  validateMessagePayload,
  BridgeMessageType,
} from '../protocols/message-protocol';

import {
  checkRateLimit,
  enforceRateLimit,
  RateLimitConfig,
  RateLimitResult,
} from '../protocols/security-protocol';

embedded-adapter.service.ts

import {
  validateMessagePayload,
  BridgeMessageType,
} from '../protocols/message-protocol';

import {
  checkRateLimit,
  RateLimitConfig,
} from '../protocols/security-protocol';

ai-iframe-test.component.ts

import {
  sanitizeForLogging,
} from '@libs-ux/embeddable-bridge';

Testing Verification Needed

Please verify the following with browser testing:

Test 1: Rate Limiting

// Send 50+ rapid messages
for (let i = 0; i < 50; i++) {
  window.postMessage({
    type: 'AI_PING',
    payload: { testNum: i },
    timestamp: Date.now()
  }, '*');
}
// Expected: Warning messages in console after ~80 messages (80% of 100)

Test 2: Token Sanitization

1. Click "Send Auth"
2. Check Message Log UI
3. Expected: Token appears as [REDACTED] not as actual value

Test 3: Payload Validation

// Send empty auth token
window.postMessage({
  type: 'AI_AUTH_INIT',
  payload: { accessToken: '' },
  timestamp: Date.now()
}, '*');
// Expected: Warning in console: "Payload validation failed for message type: AI_AUTH_INIT"

Test 4: Origin Logging

1. With debug: true enabled
2. Check console for messages like: [Embeddable Host] Sent message: AI_PING -> targetOrigin: http://localhost:5300
3. Verify: targetOrigin is NEVER '*'

Files Modified Summary

Recommended Next Steps

1. Verify Build: Run nx build embeddable-bridge and nx build gograb-space
2. Browser Testing: Run the verification tests above
3. Create New Test Report: Document actual results
4. Consider: Adding onExceeded: 'block' for stricter rate limiting in production

Fixes applied by Claude Code Agent in response to Cowork Browser Agent test feedback