A method for detecting hypertext transfer protocol secure (HTTPS) flood denial-of-service (DDoS) attacks. The method estimating traffic telemetries of at least ingress traffic directed to a protected entity; providing at least one rate-base feature and at least one rate-invariant feature based on the estimated traffic telemetries, wherein the rate-base feature and the rate-invariant feature demonstrate a normal behavior of HTTPS traffic directed to the protected entity; evaluating the at least one rate-base feature and the at least one rate-invariant feature with respect to at least one baseline to determine whether the behavior of the at least HTTPS traffic indicates a potential HTTPS flood DDoS attack; and causing execution of a mitigation action when an indication of a potential HTTPS flood DDoS attack is determined.