D2D, or direct-to-device connectivity, is a model where satellites or other non-terrestrial networks connect directly to consumer phones and similar devices without a traditional ground relay. It extends coverage into remote or disrupted areas, but it also changes the security boundary: the service now depends on spectrum rights, radio protocols, device authentication, and the systems that broker traffic between space and mobile networks.
For defenders, D2D can improve resilience during outages and broaden emergency communications options. For attackers, the architecture creates opportunities around spoofed signaling, unauthorized access, weak provisioning, and interception at gateways or management layers. Security teams should treat D2D as a converged satellite-mobile service, with strong identity checks, encrypted transport, careful spectrum governance, and clear data-handling rules.