Risky Bulletin: Chinese APT uses SS7, Diameter attacks to spy on targets

A newly discovered Chinese cyber-espionage group, tracked as SilentAir, is hacking telecommunications providers across Asia to exploit the SS7 and Diameter signalling protocols, according to telco security firm ENEA. The group plants backdoors that collect device data, track a subscriber’s location and can intercept calls and SMS traffic. ENEA says the group has been active since at least early 2025, with most targets at Taiwanese telcos and some high-value political and government individuals.