Phase 5+: Enhanced Security Hardening - Handoff Document

Session: 73.13+ Date: 2026-01-29 Author: Claude Code Agent Status: Implementation Complete - Ready for Testing Handoff To: Cowork Browser Agent

Executive Summary

Following the successful verification of Phase 5 initial fixes (4/4 passing), additional security hardening has been implemented based on senior developer code review. This document provides testing instructions for the enhanced security measures.

Previous Score: 85% (6/7 tasks) Target Score: 95%+ with enhanced protections

New Security Measures Implemented

1. Wildcard Origin Removal in AI_APP_READY (CRITICAL FIX)

Problem Found: main.ts was sending AI_APP_READY with '*' targetOrigin, bypassing all origin security.

Fix Applied: Removed direct postMessage from main.ts:44-50. Now relies entirely on EmbeddedAdapterService.notifyReady() which uses:

1. document.referrer origin detection
2. Configured allowedOrigins fallback
3. Only uses '*' as last resort with warning

File Modified: apps/gograb-ai/src/main.ts

Testing Required:

// In browser console on host page, check if embedded app sends to specific origin
// Watch for: "[Embeddable Embedded] Sent message: AI_APP_READY -> targetOrigin: http://localhost:5200"
// Should NOT see: "targetOrigin: *"

2. Expanded Payload Validators (7 new validators)

Problem Found: Only 3/40+ message types had payload validation.

Fix Applied: Added validators for critical message types in message-protocol.ts:

Testing Required:

// Test 1: Context with oversized string (should fail)
window.postMessage({
  type: 'AI_CONTEXT_UPDATE',
  payload: { contextType: 'a'.repeat(1001) },
  timestamp: Date.now()
}, '*');
// Expected: "Payload validation failed for message type: AI_CONTEXT_UPDATE"

// Test 2: Stream chunk with huge content (should fail)
window.postMessage({
  type: 'AI_STREAM_CHUNK',
  payload: {
    streamId: 'test',
    content: 'x'.repeat(1024 * 1024 + 1), // > 1MB
    index: 0,
    isComplete: false
  },
  timestamp: Date.now()
}, '*');
// Expected: "Payload validation failed for message type: AI_STREAM_CHUNK"

// Test 3: Panel resize with negative dimensions (should fail)
window.postMessage({
  type: 'AI_PANEL_RESIZE',
  payload: { width: -100 },
  timestamp: Date.now()
}, '*');
// Expected: "Payload validation failed for message type: AI_PANEL_RESIZE"

3. Global Rate Limit (Prevents Type-Flooding)

Problem Found: Rate limit was per ${origin}:${message.type}. Attacker could send 40 different message types at 99 requests each = 3960 requests without triggering limit.

Fix Applied: Added 3-layer rate limiting architecture:

Layer 1: GLOBAL (500 messages / 10 seconds, BLOCKS)
    All messages from same origin combined
    Key: `global:${origin}`

Layer 2: AUTH-SPECIFIC (10 messages / 60 seconds, BLOCKS)
    AI_AUTH_INIT, AI_AUTH_REFRESH, AI_AUTH_REQUEST_REFRESH
    Key: `auth:${origin}`

Layer 3: PER-TYPE (100 messages / 10 seconds, WARNS)
    Individual message types
    Key: `${origin}:${message.type}`

Testing Required:

// Test 1: Global rate limit (send 501+ messages rapidly)
for (let i = 0; i < 510; i++) {
  window.postMessage({
    type: ['AI_PING', 'AI_CONTEXT_UPDATE', 'AI_PANEL_TOGGLE'][i % 3], // Different types
    payload: { test: i },
    timestamp: Date.now()
  }, '*');
}
// Expected at message 501: "Global rate limit exceeded - blocking all messages from origin"

// Test 2: Auth rate limit (send 11+ auth messages in 1 minute)
for (let i = 0; i < 15; i++) {
  window.postMessage({
    type: 'AI_AUTH_INIT',
    payload: { accessToken: 'test-token-' + i },
    timestamp: Date.now()
  }, '*');
}
// Expected at message 11: "Auth rate limit exceeded - blocking auth message"

4. Validation Warnings for Sensitive Types

Problem Found: No indication when sensitive message types lacked validators.

Fix Applied: Added VALIDATION_REQUIRED_TYPES set. If a message type is in this set but has no validator, a warning is logged (once per type).

Testing Required:

// Send a message type that's in VALIDATION_REQUIRED_TYPES but may not have validator
// (If you see warning, that type needs a validator added)
window.postMessage({
  type: 'AI_DRAG_END',
  payload: { test: true },
  timestamp: Date.now()
}, '*');
// May see: "[Embeddable Bridge] Message type 'AI_DRAG_END' should have a payload validator..."

Complete Test Checklist

Security Tests (HIGH PRIORITY)

Regression Tests (Ensure Previous Fixes Still Work)

Files Modified (Phase 5+)

Rate Limit Configuration Reference

// In both host-adapter.service.ts and embedded-adapter.service.ts:

// Global limit (all message types combined)
globalRateLimitConfig: {
  maxRequests: 500,
  windowMs: 10000,    // 10 seconds
  onExceeded: 'block' // Hard block
}

// Auth-specific limit
authRateLimitConfig: {
  maxRequests: 10,
  windowMs: 60000,    // 1 minute
  onExceeded: 'block' // Hard block
}

// Per-type limit (configurable via config.rateLimit)
defaultRateLimitConfig: {
  maxRequests: 100,
  windowMs: 10000,    // 10 seconds
  onExceeded: 'warn'  // Logs warning but allows
}

Security Architecture Summary

Incoming Message
       │
       ▼
┌──────────────────────┐
│ 1. Origin Validation │ ── Reject if origin not in allowedOrigins
└──────────┬───────────┘
           │
           ▼
┌──────────────────────┐
│ 2. Message Type      │ ── Reject if type not in VALID_MESSAGE_TYPES
│    Whitelist         │
└──────────┬───────────┘
           │
           ▼
┌──────────────────────┐
│ 3. Global Rate Limit │ ── BLOCK if 500+ msgs/10s from origin
│    (all types)       │
└──────────┬───────────┘
           │
           ▼
┌──────────────────────┐
│ 4. Auth Rate Limit   │ ── BLOCK if 10+ auth msgs/60s
│    (auth types only) │
└──────────┬───────────┘
           │
           ▼
┌──────────────────────┐
│ 5. Per-Type Rate     │ ── WARN if 100+ msgs/10s per type
│    Limit             │
└──────────┬───────────┘
           │
           ▼
┌──────────────────────┐
│ 6. Payload           │ ── Reject if validator fails
│    Validation        │
└──────────┬───────────┘
           │
           ▼
┌──────────────────────┐
│ 7. Instance ID       │ ── Reject if invalid format
│    Validation        │
└──────────┬───────────┘
           │
           ▼
      ✅ PROCESS MESSAGE

Request for Verification

Dear Cowork Agent,

Please verify the following enhanced security measures:

1. Origin Hardening: Is AI_APP_READY now sent with specific origin instead of '*'?

2. Payload Validators: Do the new validators correctly reject:

   • Oversized strings (>1000 chars)
   • Oversized stream chunks (>1MB)
   • Invalid dimensions (negative/excessive)

3. Global Rate Limit: Does the 500/10s global limit prevent type-flooding attacks?

4. Auth Rate Limit: Does the 10/60s auth limit prevent brute force attempts?

5. Backward Compatibility: Do existing features still work correctly?

Please be brutally honest about any gaps or edge cases found.

Deliverable

Please create a verification report at: docs/english/sessions/editor2/session-73/phase5-enhanced-verification-report.md

Include:

1. Test results (pass/fail with evidence)
2. Any new vulnerabilities discovered
3. Edge cases tested
4. Performance impact observations
5. Recommendations for further hardening

Document created for cross-agent collaboration - Session 73.13