Which solution will give the Lambda function access to the DynamoDB table MOST securely?
Create an IAM user with programmatic access to the Lambda function. Attach a policy to the user that allows read and write access to the DynamoDB table. Store the access_key_id and secret_access_key parameters as part of the Lambda environment variables. Ensure that other AWS users do not have read and write access to the Lambda function configuration.
Create an IAM role that includes Lambda as a trusted service. Attach a policy to the role that allows read and write access to the DynamoDB table. Update the configuration of the Lambda function to use the new role as the execution role.
Create an IAM user with programmatic access to the Lambda function. Attach a policy to the user that allows read and write access to the DynamoDB table. Store the access_key_id and secret_access_key parameters in AWS Systems Manager Parameter Store as secure string parameters. Update the Lambda function code to retrieve the secure string parameters before connecting to the DynamoDB table.
Create an IAM role that includes DynamoDB as a trusted service. Attach a policy to the role that allows read and write access from the Lambda function. Update the code of the Lambda function to attach to the new role as an execution role.
Explanations:
Creating an IAM user for the Lambda function is not secure, as it requires managing access keys, which can lead to potential exposure. Additionally, using environment variables for storing sensitive information is not recommended, as it can be accessed easily if the Lambda function’s configuration is compromised.
Creating an IAM role for Lambda is the best practice. It allows Lambda to assume the role, giving it the necessary permissions to access the DynamoDB table without exposing any credentials. This method follows the principle of least privilege and enhances security by leveraging IAM roles instead of static access keys.
While using AWS Systems Manager Parameter Store to store access keys as secure strings adds a layer of security, the need to create an IAM user and manage access keys still introduces risk. The best practice is to avoid using IAM users and access keys altogether for Lambda functions.
This option incorrectly states that DynamoDB should be the trusted service for the IAM role. The trusted entity should be Lambda itself, not DynamoDB. This misconfiguration would not allow the Lambda function to assume the role properly, rendering it ineffective for accessing the DynamoDB table.
I have a feeling that the answer is:
Create an IAM role that includes Lambda as a trusted service. Attach a policy to the role that allows read and write access to the DynamoDB table. Update the configuration of the Lambda function to use the new role as the execution role.