A legacy broadcast band is an older radio transmission range that is still active, but is no longer the center of new deployments. Examples include long-standing AM-style services that continue to work even as newer platforms take over. The term matters because older bands often support devices built long ago, with limited updates, weak authentication, or no modern security features.
In cyber security, legacy bands can become part of resilience planning and attack surface analysis. They may be used for emergency messaging, industrial telemetry, or consumer receivers that still need dependable service. Attackers can abuse them with jamming, signal spoofing, or simple disruption, while defenders may respond by monitoring spectrum use, adding bridge hardware, or retrofitting old equipment so it can stay useful without relying entirely on aging infrastructure. In practice, a legacy band is not just obsolete spectrum; it is a live dependency that can affect availability, trust, and device lifecycle management.