Host software is the component of a remote-access product that is installed on the machine being controlled. It runs on the endpoint, accepts remote connections, and often enables unattended access so an administrator or support agent can reach the device even when no one is present. In practice, the host side may handle session setup, authentication, file transfer, screen sharing, and remote administration functions.
This matters in cyber security because host software sits on a high-trust machine and can provide a direct path to sensitive systems. If it is misconfigured or vulnerable, an attacker may use it to gain persistent remote control, bypass normal user interaction, or move deeper into a network. Defenders treat host software as part of the attack surface: they inventory every installation, patch it quickly, restrict who can connect, and monitor for unauthorized sessions or unusual configuration changes.