According to security best practices, how should an Amazon EC2 instance be given access to an Amazon S3 bucket?
Hard code an IAM user’s secret key and access key directly in the application, and upload the file.
Store the IAM user’s secret key and access key in a text file on the EC2 instance, read the keys, then upload the file.
Have the EC2 instance assume a role to obtain the privileges to upload the file.
Modify the S3 bucket policy so that any service can upload to it at any time.
Explanations:
Hard coding IAM user access keys directly in the application is a poor security practice. It exposes the keys to anyone with access to the code, increasing the risk of unauthorized access. Best practices recommend using IAM roles instead.
Storing IAM user access keys in a text file on the EC2 instance is also insecure. This method leaves the keys vulnerable to being read by any user or process that has access to the instance, which can lead to security breaches.
Having the EC2 instance assume an IAM role is the recommended approach. It allows the instance to obtain temporary security credentials that grant it the necessary permissions to interact with S3. This method avoids hard coding keys and enhances security.
Modifying the S3 bucket policy to allow any service to upload to it is a significant security risk. It opens the bucket to potentially malicious uploads from any source, undermining the principle of least privilege and exposing the bucket to unauthorized access.
I measure that the answer is:
Have the EC2 instance assume a role to obtain the privileges to upload the file.