webhook-security

Webhook Security Best Practices

Signature Verification

• ALWAYS verify webhook signatures using timing-safe comparison
• Never accept webhooks without proper signature validation
• Use environment variables for webhook secrets
• Implement multiple signature algorithm support when available
• Log signature verification failures for security monitoring
• Never expose signature verification logic in error messages
• Use raw request body for signature validation (before JSON parsing)

Request Validation

• Validate all webhook payload fields before processing
• Implement strict JSON schema validation
• Check for required fields and proper data types
• Sanitize all input data before database operations
• Validate webhook event types against expected values
• Implement payload size limits to prevent DoS attacks
• Check request headers for proper content-type

Idempotency

• Implement idempotency using unique event identifiers
• Store processed webhook IDs to prevent duplicate processing
• Use database transactions for atomic operations
• Handle race conditions with proper locking mechanisms
• Implement retry logic for failed webhook processing
• Set appropriate timeouts for database operations
• Log all idempotency checks and outcomes

Error Handling

• Return proper HTTP status codes (200 for success, 4xx for client errors)
• Implement comprehensive try/catch blocks
• Log all webhook processing errors with context
• Never expose internal error details in responses
• Implement graceful degradation for non-critical failures
• Use structured logging for better error analysis
• Set up alerts for webhook failure patterns

Rate Limiting

• Implement rate limiting per webhook source
• Use sliding window or token bucket algorithms
• Configure different limits for different event types
• Monitor and alert on rate limit violations
• Implement progressive backoff for repeated violations
• Log all rate limiting actions
• Allow for burst traffic during normal operations