Two security researchers have found undocumented Telnet admin account accounts in 29 Fiber-To-The-Home (FTTH) devices from Chinese vendor C-Data. Backdoor accounts in the firmware of 29 FTTH Optical Line Termination (OLT) devices could allow users access to a secret Telnet administrator account running on the devices external WAN interface granting them full administrator access. The researchers pointed out that the initial backdoor. access could be used by attackers to extract. administrator credentials by running a command in the. CLI.”]
Source: https://securityaffairs.co/wordpress/105762/hacking/c-data-ftth-devices-backdoors.html