How to Secure Serverless Applications on AWS Lambda

November 30, 20235 min read

Serverless computing is an execution model where the cloud provider dynamically manages the allocation of machine resources. AWS Lambda is a serverless computing service provided by Amazon Web Services (AWS) that runs code in response to events and automatically manages the underlying compute resources. While the serverless architecture offers a number of advantages in terms of scalability and cost, it also introduces unique security considerations. Below is a detailed guide on how to secure serverless applications on AWS Lambda.

Understanding the Shared Responsibility Model

Before diving into the specifics of security, it’s important to understand the shared responsibility model in cloud computing:

  • AWS’s Responsibility: AWS is responsible for the security of the cloud itself. This includes the infrastructure that runs all of the services offered in the AWS Cloud. AWS also provides various tools that you can use to secure your resources.
  • Customer’s Responsibility: As the AWS customer, you’re responsible for securing your data and applications that run in the AWS cloud. This includes elements like customer data, platform, applications, IAM roles, and encryption.

Securing your AWS Lambda environment

1. Apply the Principle of Least Privilege

  • Define IAM Roles: Create AWS Identity and Access Management (IAM) roles with the minimum set of permissions necessary for your Lambda functions to perform their tasks.
  • Limit Access: Apply strict permission policies for accessing Lambda functions and related resources like S3 buckets, databases, and other AWS services.

2. Keep Your Functions Lean

  • Minimal Code: Deploy only the necessary code and libraries within your Lambda functions. This minimizes the attack surface and reduces the chance of including vulnerable code.

3. Secure Your Function Configuration

  • Environment Variables: Encrypt sensitive information such as database passwords and API keys using AWS Lambda environment variables and AWS Key Management Service (KMS).

4. Secure API Gateway

  • API Authorization: Integrate AWS Lambda with Amazon API Gateway and use JWT tokens, OAuth, or AWS Cognito for controlling access to your APIs.
  • Throttling: Set up throttling rules to limit the number of requests a user can make to your API Gateway in a given period of time.

5. Use VPCs and Secure Network Connections

  • Resource Isolation: If necessary, run your Lambda function in a Virtual Private Cloud (VPC) to provide network isolation.
  • Secure Data Transfer: Always use HTTPS to encrypt data transferred between AWS services and Lambda.

Monitoring and Logging

1. Enable AWS CloudTrail and Amazon CloudWatch

  • CloudTrail: Ensure AWS CloudTrail is enabled to log API calls for Lambda and other AWS services that it interacts with. This aids in auditing and real-time monitoring.
  • CloudWatch: Use Amazon CloudWatch metrics and alarms to monitor function execution and performance. Create alarms for any unexpected behavior.

2. Logging Best Practices

  • Log Management: Make use of AWS Lambda execution logs and output them to CloudWatch. Monitor and analyze these logs for any unusual activity or errors.

Vulnerability Management

1. Regularly Update Your Code

  • Patch Libraries: Continuously monitor and patch any libraries or dependencies used within your Lambda function to address security vulnerabilities.

2. Dependency Scanning

  • Automate Scanning: Implement automated vulnerability scanning for your code and dependencies using tools such as AWS CodePipeline together with third-party security tools.

Deploying Secure Serverless Applications

1. Automate Deployments

  • CI/CD Pipeline: Use AWS CodePipeline, AWS CodeBuild, and AWS CodeDeploy to automate the deployment of Lambda functions and to manage infrastructure as code.

2. Infrastructure as Code

  • Templates: Utilize AWS CloudFormation or the Serverless Application Model (SAM) to define and deploy your serverless infrastructure as code. This ensures a repeatable and version-controlled deployment process.

3. Secure CI/CD Environment

  • CI/CD Security: Secure your CI/CD environment to prevent unauthorized modification of the pipeline and Lambda code.


Securing serverless applications on AWS Lambda requires a thorough approach that involves setting correct permissions, securing network connections, managing dependencies, and continuous monitoring and logging. By following AWS best practices and implementing a comprehensive security strategy, you can significantly reduce the risk of a security breach in your serverless applications.