Which feature of AWS enhances security against unauthorized access?

Multi-Factor Authentication (MFA) is a crucial security feature provided by AWS that enhances protection against unauthorized access. By requiring users to provide two or more verification factors to gain access to an AWS resource, MFA significantly reduces the risk of breaches that could occur from compromised credentials.

When MFA is enabled, even if a user's password is stolen or guessed, the attacker would still need the second factor (such as a temporary code generated by an authenticator app or sent via SMS) to successfully access the account. This additional layer of security is essential in safeguarding sensitive data and maintaining the integrity of AWS environments.

Other options, while valuable in their own right, do not focus specifically on enhancing security against unauthorized access in the same way that MFA does. CloudFormation is primarily an infrastructure as code service, allowing users to define and provision AWS infrastructure through templates. Elastic Load Balancing distributes incoming application traffic across multiple targets but does not provide access control features. S3 Access Control Lists can manage permissions for individual resources but do not inherently provide the same level of security against unauthorized access that MFA offers across all AWS services.