We investigate the Spectral Kurtosis (SK) statistical signature of a signal observed with the Robert C. Byrd Green Bank Telescope Breakthrough Listen back-end that was transmitted by the Voyager 1 spacecraft, which is up to date the only known artificial signal originating from outside our solar system, and we demonstrate the ability of the SK estimator to perform real-time detection and discrimination against natural astronomical transients of deep-space Voyager 1-like technological signatures of alien origin. We use the same approach to investigate the yet controversial nature of the FRB 180301 signal detected during the Breakthrough Listen observations with the Parkes telescope.