Serverless Security: Best Practices And Practical Tips

Hello intrepid reader! Today, we're diving into the world of serverless security.

Serverless architectures, much like microservices, are a popular way to build and deploy applications. They help take infrastructure management off your plate and onto your cloud provider's. This naturally frees up all your time to think about security.

Like normal applications, ensuring the security of your serverless applications is crucial. Let’s explore some best practices to keep your functions safe and sound.

Understanding Serverless Application Security

Before we dive into best practices, let's understand what serverless security entails. In a serverless architecture, you offload server management to a cloud provider. This reduces certain security responsibilities but introduces new challenges.

Focus on securing each function and its data in your application. Also, pay attention to securing the interactions between them. Don't just focus on securing the application as a whole. Securing one or a few functions is manageable, but securing many serverless functions can become complex quickly.

Best Practices for Securing Serverless Applications

1. Principle of Least Privilege

Only grant your functions the permissions they absolutely need. This minimizes the risk of someone exploiting a function to access other resources.

How to Implement:

• Use role-based access control (RBAC) to assign minimal permissions.
• Regularly audit and refine permissions to ensure they remain minimal.

2. Environment Variable Management

Environment variables often store sensitive information like API keys and database credentials. Handling them securely is paramount.

How to Implement:

• Use secret management services provided by your cloud provider, such as AWS Secrets Manager or Azure Key Vault.
• Like in normal application development, avoid hardcoding sensitive information, like api keys, in your code.

Bismuth offers configuration management built directly into our platform. All you need to do is drop in a few lines of code to begin using it.

3. Input Validation and Sanitization

Serverless functions need strong input validation to protect against injection attacks when handling data from different sources.

How to Implement:

• Validate all incoming data against a schema.
• Sanitize inputs to remove potentially malicious content.
• Use libraries and frameworks that offer built-in protection against common vulnerabilities.

Bismuth primarily leverages Flask in our SDK which has well known integrations for input sanitization and validation.

4. Monitoring and Logging

Implement comprehensive monitoring and logging to detect and respond to suspicious activities quickly.

How to Implement:

• Enable detailed logging for your functions.
• Use a centralized logging system to aggregate and analyze logs.
• Implement real-time monitoring and alerting for abnormal behavior.

Bismuth has built logging and application monitoring directly into it. Once you deploy your application, you can access logs streamed right into our cloud console.

5. Network Security

Even though you don’t manage servers, network security still matters. Ensure secure communication between your functions and other services.

How to Implement:

• Use virtual private networks (VPNs) and virtual private clouds (VPCs) to isolate your serverless functions.
• Enable TLS to encrypt data in transit.
• Implement API gateways to control access and enforce security policies.

Bismuth makes sure that different functions and applications on our platform are kept isolated to enhance security.

There are some other network security methods like mTLS, but these are a bit harder to use on FaaS, and are more common to microservices where service meshes make it more trivial. We compare serverless and microservices in another post to further explain differences between the two architectures.

6. Code Security

Your function code can be an entry point for attackers. Secure coding practices and regular audits are essential.

How to Implement:

• Conduct regular code reviews and security audits.
• Use static and dynamic analysis tools to identify vulnerabilities.
• Keep your dependencies updated and avoid using deprecated libraries.

7. Function Timeout and Resource Limits

To prevent functions from running for too long or using excessive resources, set timeouts and limits. This can help identify abuse or problems. 

How to Implement:

• Set reasonable timeout values for your functions based on expected execution times.
• Define memory and execution time limits to prevent resource exhaustion.

Bismuth currently has one size fits all compute for our runtime complete with network and data caps. Businesses are welcome to reach out to us if there is further interest in flexible workloads.

8. Authentication and Authorization

Ensure that only authorized users and services can invoke your functions.

How to Implement:

• Use identity and access management (IAM) policies to control who can invoke functions.
• Implement multi-factor authentication (MFA) for accessing sensitive functions.
• Use tokens and API keys for service-to-service authentication for a basic implementation.

Bismuth enables authentication and authorization in our SDK through the AuthCodeBlock, which APIs or other applications can use directly.

9. Security Patching

Even in a serverless environment, you need to keep your runtime environment and dependencies up to date.

How to Implement:

• Regularly update your function runtime and dependencies.
• Subscribe to security advisories related to the libraries and platforms you use.
• Automate the deployment of patches and updates where possible.

10. Testing and Continuous Integration

Incorporate security testing into your CI/CD pipeline to catch vulnerabilities early.

How to Implement:

• Integrate security testing tools into your CI/CD pipeline.
• Perform regular security testing, including penetration tests and vulnerability scans.
• Automate testing processes to ensure consistent and thorough coverage.

Conclusion

Securing serverless applications involves a combination of traditional security practices and new strategies tailored to the serverless model. By following these best practices, you can mitigate risks and ensure your serverless functions remain robust and secure. Remember, security is an ongoing process—stay vigilant, keep learning, and practice defense in depth. Implementing these tips is sure to improve your security posture.

I hope you found this guide helpful! For more insights on serverless architecture why don't you check out our deep dive post on serverless architecture. Happy coding, and stay secure!