China-Linked Fire Ant Turned Cisco Routers, TACACS Servers Into Espionage Platforms

The China-nexus espionage group Fire Ant has moved from compromising virtualization platforms to implanting Cisco IOS XR routers and TACACS authentication servers. They are using them to capture traffic, harvest administrator credentials and suppress the logs defenders rely on, said researchers at Sygnia, an incident response firm. Researchers first documented Fire Ant in July 2025 for deep intrusions into VMware ESXi and vCenter environments. The new report describes the same actor operating a layer lower, in what researchers call the trust layer — the routers, authentication servers and Linu