OS

The software that manages hardware and runs applications.

An Operating System manages hardware resources and provides the foundation on which applications run, mediating access to memory, storage, processes, and the network. Its security posture depends on timely patching, secure configuration, least-privilege accounts, and hardening to reduce the attack surface. Because the OS enforces isolation between users and processes, a kernel-level compromise can undermine every control above it. Maintaining a known-good baseline and disabling unnecessary services are core defensive practices tied directly to host security.