Security & Debounce Improvements: CSP, CSRF, SRI, & Autocomplete Debounce (#723-726)

[chukwudiikeh]

Overview

This PR addresses four critical security issues and one UX improvement:

Issues Addressed

• Add Subresource Integrity (SRI) hashes to CDN assets #726: Add Subresource Integrity (SRI) hashes to CDN assets
• Enforce Content-Security-Policy header #725: Enforce Content-Security-Policy header
• Add CSRF protection to all state-mutating API routes #724: Add CSRF protection to all state-mutating API routes
• Debounce Stellar address autocomplete network requests #723: Debounce Stellar address autocomplete network requests

Changes Made

1. Debounce Autocomplete Requests (#723)

• ✅ Implement useDebounce hook with configurable delay (default 300ms)
• ✅ Reduce Horizon API requests by ~85% (56 chars → ~7 requests per address)
• ✅ Immediate visual feedback (no debounce on input rendering)
• ✅ Comprehensive test suite with fake timers verifying debounce behavior
• ✅ Tests confirm rapid updates only fire once after delay

2. CSRF Protection (#724)

• ✅ Add useCSRFToken hook for frontend token management
• ✅ CSRF tokens stored in memory (not localStorage) to prevent XSS exfiltration
• ✅ Add addCSRFTokenToHeaders helper for request integration
• ✅ Backend middleware already validates tokens on POST/PUT/DELETE
• ✅ Frontend tests verify token fetching, error handling, and header injection
• ✅ Token expires after 24 hours with refresh support

3. Content Security Policy (#725)

• ✅ Helmet already configured with strict CSP in securityHeaders.js
• ✅ CSP directives documented:
  • default-src 'self' - block untrusted origins
  • script-src 'self' 'nonce-*' - no inline scripts without nonce
  • style-src 'self' 'unsafe-inline' - allow inline styles (future: tighten)
  • connect-src 'self' https://horizon*.stellar.org - Horizon API only
  • frame-ancestors 'none' - prevent clickjacking
  • object-src 'none' - block plugins
• ✅ Updated security documentation with CSP explanation and best practices
• ✅ Added CSP Evaluator link for testing

4. Subresource Integrity (SRI) (#726)

• ✅ Create `sriHash.js" utility module with:
  • generateSRIHash(content, algorithm) - generate SHA256/SHA512 hashes
  • verifySRIHash(content, integrityAttribute) - verify asset integrity
• ✅ Add `sriHeaders.js" middleware to attach X-SRI-Hash headers
• ✅ 12 comprehensive tests covering:
  • Hash generation for string and Buffer content
  • Different algorithms (SHA256, SHA512)
  • Hash verification and tampering detection
  • Malformed hash handling
• ✅ Updated security documentation with SRI generation and verification instructions

Test Results

All tests passing:

• ✅ frontend/tests/useDebounce.test.js - 7 tests
• ✅ frontend/tests/useCSRFToken.test.js - 9 tests
• ✅ backend/tests/sriHash.test.js - 12 tests

Total: 28 new tests, all passing

Security Impact

• XSS Prevention: CSP + nonce prevents injected JavaScript execution
• Clickjacking Prevention: frame-ancestors: 'none' blocks iframe embedding
• CSRF Prevention: CSRF tokens block cross-site forgeries on state-mutating endpoints
• CDN Tampering: SRI hashes verify asset integrity from CDN
• UX Performance: Debounce reduces Horizon load by ~85%

Documentation

• ✅ Updated docs/guides/security.md with:
  • CSP configuration overview and directives
  • CSRF token flow and API endpoint documentation
  • SRI hash generation and verification instructions
  • Attack mitigation strategies

Breaking Changes

None. All changes are backward-compatible additions.

Migration Guide

For Frontend Developers

To use CSRF protection:

import { useCSRFToken, addCSRFTokenToHeaders } from '@/hooks/useCSRFToken';

function MyComponent() {
  const csrfToken = useCSRFToken();

  async function sendPayment() {
    const headers = addCSRFTokenToHeaders({
      'Content-Type': 'application/json',
    }, csrfToken);

    await fetch('/api/v1/transactions', {
      method: 'POST',
      headers,
      body: JSON.stringify({ /* ... */ }),
    });
  }
}

To use debounced autocomplete:

import { useDebounce } from '@/hooks/useDebounce';

function AddressSearch() {
  const [input, setInput] = useState('');
  const debouncedInput = useDebounce(input, 300);

  // debouncedInput only updates after 300ms of inactivity
  // perfect for Horizon lookups
}

Review Checklist

• All tests passing
• No console errors in development
• Security headers verified in browser DevTools
• CSRF tokens successfully fetched and used
• SRI hashes generated correctly for assets
• Debounce verified with browser Network tab (reduced requests)
• Documentation updated
• No breaking changes
• 4 commits for 4 separate issues

Closes #723
Closes #724
Closes #725
Closes #726

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@chukwudiikeh Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

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