An e-commerce platform hosted on a public cloud infrastructure begins to experience significant latency and timeout issues during its peak sales hours. Security logs indicate thousands of incoming HTTP connections, each of which starts sending headers extremely slowly and never completes the full request. Over time, the number of open connections rises beyond the server's handling capacity, leading to system instability and service unavailability. The network team verifies that these connections are not transmitting malformed packets or high volumes of traffic and appear to originate from legitimate IPs. Which specific DoS technique is most likely responsible for the degradation of service?