To reduce the attack surface of a system, administrators should perform which of the following processes to remove unnecessary software, services, and insecure configuration settings?

Harvesting refers to collecting data or credentials from a target system and is not a defensive configuration process.

Windowing is not a recognized security configuration process - it typically refers to time-based filtering in networking or data processing contexts.

Hardening refers to the systematic process of securing a system by disabling or removing unnecessary services and software, applying security patches, and correcting insecure default configurations. This directly reduces the attack surface by eliminating potential entry points an attacker could exploit. It is a foundational security practice codified in frameworks such as CIS Benchmarks and NIST SP 800-123.

Stealthing refers to concealing a system or its open ports from network scanning, not to removing unnecessary services or correcting insecure settings.