CVE-2020-15314

Vulnerability

Zyxel CloudCNM SecuManager versions 3.1.0 and 3.1.1 use a hardcoded RSA SSH private key for the root account. This key is identical across all installations, including those used for chroot environments [1]. An attacker who obtains this key can impersonate the server or decrypt SSH traffic.

Exploitation

An attacker with network access to the SecuManager (which may be reachable from the WAN [1]) can perform a man-in-the-middle (MITM) attack. By using the known hardcoded key, the attacker can intercept and decrypt SSH sessions, or establish a fraudulent SSH session with a client [1]. No authentication or user interaction is required beyond network proximity.

Impact

Successful exploitation results in complete loss of confidentiality for SSH communications. An attacker can capture sensitive data, such as administrative credentials, configuration files, or other secrets transmitted over SSH. This could lead to full compromise of the management appliance [1].

Mitigation

As of the publication date, no official patch or updated version has been released to address this issue [1]. Users should restrict network access to the SecuManager to trusted hosts only and consider using additional encryption or VPN layers for management traffic. If possible, regenerate SSH host keys on the device (if supported) and monitor for unauthorized access.