Protocol-Compliant Back-to-Origin Amplification in Satellite-Enabled CDNs

Satellite-enabled content delivery networks (S-CDNs) are needed to improve content access for wide-area, remote, and highly dynamic users, for whom relying only on terrestrial CDN infrastructure is often insufficient. However, in conventional CDN systems, request acceptance and origin fetching are not tightly coupled. In satellite–ground environments with high latency, dynamic connectivity, and limited observability of requester state, low-cost and fully protocol-compliant requests may still trigger disproportionate backend work. This paper attributes the problem to open-loop request admission and studies two protocol-compliant paths. The range path is an instance of a known CDN cost asymmetry. The second path, called “Disconnection-induced amplification after request submission,” builds on known connection-decoupling behavior. Its attack realization is a protocol-compliant requester-side stop inspired by satellite coverage motion. The stop emulates the observable effect of a user leaving the service area after task triggering. The experiment evaluates this emulation. Experiments on an in-orbit prototype and a matched terrestrial configuration, together with supplementary analysis, show substantial back-to-origin amplification along both paths: the smallest byte-range request on uncached objects reaches a peak amplification of about 15,000, while the disconnection-induced path causes persistent satellite-side bandwidth occupation, a lower benign completion ratio, and higher downlink overhead. These findings indicate that cache misses in S-CDNs are not only performance events but also security-relevant points of backend commitment.