Customer.io Security Basics

Overview

Implement security best practices for Customer.io integrations including credential management, PII handling, and access controls.

Prerequisites

Customer.io account with admin access
Understanding of your data classification
Environment variable management

Instructions

Step 1: Secure Credential Management

// lib/secrets.ts
import { SecretManagerServiceClient } from '@google-cloud/secret-manager';

// Use a secrets manager instead of env vars for production
async function getCustomerIOCredentials(): Promise<{
  siteId: string;
  apiKey: string;
}> {
  // Option 1: Google Cloud Secret Manager
  const client = new SecretManagerServiceClient();
  const [siteIdVersion] = await client.accessSecretVersion({
    name: 'projects/PROJECT_ID/secrets/customerio-site-id/versions/latest'
  });
  const [apiKeyVersion] = await client.accessSecretVersion({
    name: 'projects/PROJECT_ID/secrets/customerio-api-key/versions/latest'
  });

  return {
    siteId: siteIdVersion.payload?.data?.toString() || '',
    apiKey: apiKeyVersion.payload?.data?.toString() || ''
  };
}

// Option 2: AWS Secrets Manager
import { SecretsManager } from '@aws-sdk/client-secrets-manager';

async function getCredentialsFromAWS() {
  const client = new SecretsManager({ region: 'us-east-1' });
  const response = await client.getSecretValue({
    SecretId: 'customerio-credentials'
  });
  return JSON.parse(response.SecretString || '{}');
}

Step 2: PII Data Handling

// lib/pii-handler.ts
import crypto from 'crypto';

// Hash sensitive identifiers before sending
function hashPII(value: string): string {
  return crypto
    .createHash('sha256')
    .update(value + process.env.PII_SALT)
    .digest('hex');
}

// Sanitize attributes before sending to Customer.io
function sanitizeUserAttributes(attributes: Record<string, any>): Record<string, any> {
  const sensitiveFields = ['ssn', 'credit_card', 'password', 'bank_account'];
  const piiFields = ['phone', 'address', 'date_of_birth'];

  const sanitized = { ...attributes };

  // Remove highly sensitive fields
  for (const field of sensitiveFields) {
    delete sanitized[field];
  }

  // Hash PII fields if needed for matching but not display
  for (const field of piiFields) {
    if (sanitized[field]) {
      sanitized[`${field}_hash`] = hashPII(sanitized[field]);
      // Optionally remove plain text version
      // delete sanitized[field];
    }
  }

  return sanitized;
}

// Usage
const safeAttributes = sanitizeUserAttributes({
  email: 'user@example.com',
  phone: '+1234567890',
  ssn: '123-45-6789', // Will be removed
  plan: 'premium'
});

Step 3: API Key Rotation

// scripts/rotate-api-key.ts
async function rotateAPIKey(): Promise<void> {
  console.log('API Key Rotation Checklist:');
  console.log('1. Generate new API key in Customer.io dashboard');
  console.log('2. Update secrets manager with new key');
  console.log('3. Deploy application with new key');
  console.log('4. Verify integration works with new key');
  console.log('5. Revoke old API key in dashboard');
  console.log('6. Update documentation');

  // Automated rotation (if using secrets manager)
  // 1. Create new key via API (if supported)
  // 2. Update secret in manager
  // 3. Wait for propagation
  // 4. Revoke old key
}

// Schedule rotation every 90 days
// Add to cron or scheduled task

Step 4: Webhook Security

// lib/webhook-security.ts
import crypto from 'crypto';
import { Request, Response, NextFunction } from 'express';

// Verify Customer.io webhook signatures
function verifyWebhookSignature(
  payload: string,
  signature: string,
  secret: string
): boolean {
  const expectedSignature = crypto
    .createHmac('sha256', secret)
    .update(payload)
    .digest('hex');

  return crypto.timingSafeEqual(
    Buffer.from(signature),
    Buffer.from(expectedSignature)
  );
}

// Express middleware for webhook verification
export function webhookAuthMiddleware(webhookSecret: string) {
  return (req: Request, res: Response, next: NextFunction) => {
    const signature = req.headers['x-cio-signature'] as string;

    if (!signature) {
      return res.status(401).json({ error: 'Missing signature' });
    }

    const payload = JSON.stringify(req.body);

    if (!verifyWebhookSignature(payload, signature, webhookSecret)) {
      return res.status(401).json({ error: 'Invalid signature' });
    }

    next();
  };
}

// Usage
app.post('/webhooks/customerio',
  webhookAuthMiddleware(process.env.CUSTOMERIO_WEBHOOK_SECRET!),
  (req, res) => {
    // Handle verified webhook
  }
);

Step 5: Access Control

// lib/access-control.ts
interface TeamMember {
  email: string;
  role: 'admin' | 'editor' | 'viewer';
  permissions: string[];
}

// Recommended role-based access
const rolePermissions = {
  admin: [
    'manage_api_keys',
    'manage_team',
    'manage_integrations',
    'view_all_data',
    'send_campaigns'
  ],
  editor: [
    'create_campaigns',
    'edit_campaigns',
    'view_analytics',
    'manage_segments'
  ],
  viewer: [
    'view_campaigns',
    'view_analytics'
  ]
};

// Audit logging for security-sensitive operations
function logSecurityEvent(event: {
  action: string;
  actor: string;
  resource: string;
  details?: Record<string, any>;
}) {
  console.log(JSON.stringify({
    type: 'security_audit',
    timestamp: new Date().toISOString(),
    ...event
  }));
}

Step 6: Data Retention

// lib/data-retention.ts
import { APIClient } from '@customerio/track';

// Suppress/delete users for GDPR/CCPA compliance
async function deleteUserData(client: APIClient, userId: string) {
  // 1. Suppress the user (stops all messaging)
  await client.suppress(userId);

  // 2. Request full deletion through Customer.io dashboard or API
  // Note: Full deletion may require support ticket

  console.log(`User ${userId} suppressed and deletion requested`);
}

// Anonymous historical data retention
function anonymizeForAnalytics(userData: Record<string, any>) {
  return {
    ...userData,
    email: undefined,
    phone: undefined,
    first_name: undefined,
    last_name: undefined,
    // Keep aggregated/analytical data
    plan: userData.plan,
    signup_date: userData.created_at,
    total_events: userData.event_count
  };
}

Security Checklist

[ ] API keys stored in secrets manager (not env vars in code)
[ ] API keys rotated every 90 days
[ ] Webhook signatures verified
[ ] PII sanitized before sending
[ ] Minimum necessary data sent to Customer.io
[ ] Team access follows least-privilege principle
[ ] Audit logging enabled for sensitive operations
[ ] GDPR/CCPA deletion process documented
[ ] SSL/TLS enforced for all API calls

Error Handling

| Issue | Solution | |-------|----------| | Exposed credentials | Rotate immediately, audit access | | PII leak | Delete from Customer.io, notify DPO | | Unauthorized access | Review access logs, revoke access |

Resources

Next Steps

After implementing security, proceed to customerio-prod-checklist for production readiness.