Webhook security best practices and checklist

Webhooks are a simple, powerful way to send automated messages or data from one service to another in real time. But their convenience also makes them attractive targets for attackers—especially when improperly secured. Here’s a comprehensive checklist of best practices to ensure your webhook implementations are resilient, reliable, and secure.

8 security best practices to follow when creating webhooks

1. Encrypt data sent through webhooks

Use HTTPS for all webhook URLs to ensure that transmitted data is encrypted in transit. This prevents man-in-the-middle (MITM) attacks and eavesdropping on sensitive information.

2. Sign your webhooks

Include a cryptographic signature with each webhook request to verify authenticity. Signing helps confirm that the webhook originated from a trusted source and that the payload hasn’t been tampered with.

3. Authenticate connections

Don’t rely solely on obscurity or firewall rules. Implement strong authentication to verify that incoming requests are legitimate. Use HMAC-based signatures, bearer tokens, or mutual TLS, as webhooks typically cannot support interactive authentication flows.

Verify source IP addresses and DNS resolution

Maintain an allowlist of IP addresses from which your webhook requests should originate. Avoid relying on reverse DNS lookups for security validation, as these can be unreliable and easily spoofed.

Use HMAC signatures to validate webhook payloads

Generate HMAC hashes using a shared secret and compare them on receipt. Ensure that timing attacks are mitigated by using constant-time comparison methods.

Implement mutual TLS (mTLS) for endpoint authentication

Mutual TLS provides two-way authentication, allowing client and server to verify each other. This adds a strong cryptographic layer to the communication.

Rotate secrets and authentication keys regularly

Keys used to sign or verify webhook payloads should be rotated periodically to limit the risk of long-term exposure from compromised credentials.

Reject unauthenticated or malformed requests

Fail securely. If a webhook request fails validation, respond with an error and ensure no processing occurs. Log the attempt and optionally trigger an alert.

4. Add timestamps to your message

Including a timestamp in webhook messages helps protect against replay attacks. Combine this with a short expiration window to reject delayed or replayed requests.

5. Use certificate pinning

If you are receiving webhook requests from a trusted third party, consider implementing certificate pinning to ensure the authenticity of the sender’s TLS certificate. However, be aware that certificate pinning can introduce operational challenges, especially during certificate renewals.

6. Don’t use webhooks for sensitive data

Minimize the sensitivity of data sent via webhooks. Avoid including personally identifiable information (PII), credentials, or other confidential information in webhook payloads. If transmitting sensitive data is unavoidable, use strong encryption, endpoint hardening, and strict access controls.

7. Implement logging for all webhook messages sent out

Comprehensive logging enables auditing and incident response. Log metadata such as timestamps, response status, and destination URLs without logging sensitive payload content.

8. Use a subscription model with expiration dates

Require webhook consumers to subscribe and include expiration dates for access. This limits long-term exposure from inactive or abandoned endpoints and enforces lifecycle management.

How Invicti can help with webhook security

Scanning webhook endpoints for vulnerabilities

Webhook URLs are typically public-facing endpoints, making them part of your application attack surface. Invicti’s dynamic application security testing (DAST) capabilities can detect common issues like injection flaws, misconfigurations, or exposure of sensitive functionality through these endpoints.

Validating authentication and access control mechanisms

Invicti supports authenticated scanning to verify that only properly authenticated and authorized requests can interact with your webhook handlers. This includes evaluating token usage, session handling, and header validation.

Preventing business logic abuse

Many webhook implementations are tightly integrated with business processes. Invicti can simulate real-world payloads to uncover logic flaws that could allow unauthorized actions, privilege escalation, or data manipulation.

Supporting secure SDLC practices for webhook integrations

By integrating Invicti into your CI/CD pipeline, you can continuously validate webhook implementations during development and deployment. This ensures consistent application of security policies across builds and environments.

Detecting exposed or undocumented webhook URLs

Invicti’s asset discovery capabilities can reveal webhook endpoints that were forgotten, misconfigured, or unintentionally exposed. These endpoints often go untested and can become high-risk liabilities if not properly secured.

With a strong foundation in DAST-first AppSec, Invicti gives organizations visibility and validation for all web-facing components—including webhook infrastructure.

FAQs: Webhook security