A company transfers data between an Amazon S3 bucket and an on-premises application. Under the AWS shared responsibility model, who is responsible for securing that data?

Under the AWS shared responsibility model, AWS is responsible for the security of the cloud (the underlying infrastructure), while the customer is responsible for security in the cloud (their data, applications, and configurations). In this scenario, the company is transferring its own data between an S3 bucket and an on-premises application. Therefore, the company is responsible for securing that data, including its encryption, access controls, and integrity during transit and at rest. AWS provides the secure infrastructure for S3 and the network, but the customer retains responsibility for the data itself. The firewall vendor is only responsible for their product, not the data it protects, and an AWS Marketplace partner is irrelevant to this core responsibility.