How can a developer configure access to the S3 bucket in the MOST secure way?
Hardcode the credentials that are required to access the S3 objects in the application code. Use the credentials to access the required S3 objects.
Create a secret access key and access key ID with permission to access the S3 bucket. Store the key and key ID in AWS Secrets Manager. Configure the application to retrieve the Secrets Manager secret and use the credentials to access the S3 objects.
Create a Lambda function execution role. Attach a policy to the role that grants access to specific objects in the S3 bucket.
Create a secret access key and access key ID with permission to access the S3 bucket. Store the key and key ID as environment variables in Lambda. Use the environment variables to access the required S3 objects.
Explanations:
Hardcoding credentials in the application code violates security best practices by exposing sensitive information. This approach is highly insecure as it allows for easy access to credentials in case the code is leaked or compromised.
Storing static access keys in AWS Secrets Manager is a better approach for storing sensitive credentials, but it still involves managing long-lived credentials. This doesn’t fully leverage temporary credentials and the security of AWS IAM roles for Lambda.
Creating a Lambda execution role with the appropriate IAM policy to grant access to specific objects in the S3 bucket is the most secure way. This allows the Lambda function to use temporary security credentials that are automatically rotated and managed by AWS, following the principle of least privilege.
Storing access keys in Lambda environment variables is not secure, as they are not dynamically rotated and are more exposed to unauthorized access. Environment variables can be viewed in Lambda logs and via the Lambda console. This approach violates security best practices.
In my opinion, the answer is:
Create a Lambda function execution role. Attach a policy to the role that grants access to specific objects in the S3 bucket.