Chinese Fire Ant Hackers Turn Cisco Routers Into Invisible Spying Platforms
A sophisticated technique allows the threat actor to hide GRE tunnels from administrators, bypassing standard configuration checks to exfiltrate network traffic.
The Chinese-linked threat actor known as Fire Ant has deployed a sophisticated method to transform Cisco IOS XR routers into covert spying platforms. By manipulating the router's control plane, the attackers can intercept and exfiltrate internal network traffic while remaining invisible to system administrators.
Fire Ant achieved this by creating active Generic Routing Encapsulation (GRE) tunnel interfaces. These tunnels provided the covert connectivity necessary for traffic collection, yet they remained entirely hidden from the device's running configuration and commit history. To maintain this stealth, the actor utilized purpose-built malware targeting the IOS XR control plane. This malware modified the command-execution path to automatically append an '| exclude' filter to 'show' commands, ensuring that any administrative attempt to list active interfaces would omit the malicious tunnels.
The Strategy of Infrastructure Targeting
Fire Ant is part of a broader trend of state-linked actors targeting networking infrastructure rather than individual endpoints. By compromising the router level, attackers can bypass host-based security controls—such as antivirus or endpoint detection and response (EDR) tools—that typically monitor servers and workstations. This positioning allows the actor to maintain long-term persistence and gain visibility into vast amounts of internal network traffic as it moves across the backbone of the organization.
Implications for Network Security
This technique represents a significant escalation in stealth because it undermines the primary trust mechanism used by network engineers. Traditionally, the 'show running-config' command is the gold standard for verifying a device's state. When an attacker can maintain a functional network interface that is invisible to these standard administrative checks, they effectively create a permanent, hidden backdoor for surveillance.
For the industry, this highlights a critical vulnerability in the assumption that the management plane of a network device is an immutable source of truth. If the very tools used to audit a system are compromised, the device can no longer be trusted, regardless of what the configuration logs indicate.
Future Outlook
Security teams are now tasked with finding alternative methods to detect such anomalies, as standard configuration audits are insufficient. Future defenses may require deeper memory forensics or external traffic analysis to identify GRE tunnels that do not appear in the official system logs. It remains to be seen how many other infrastructure devices may be harboring similar hidden interfaces, as the stealthy nature of the Fire Ant operation makes retrospective detection exceptionally difficult.