CVE-2019-15801 Explained : Impact and Mitigation

A vulnerability has been identified on Zyxel GS1900 devices running firmware versions prior to 2.50(AAHH.0)C0. The firmware package contains encoded passwords which are utilized for user authentication when accessing diagnostic or password-recovery menus. This vulnerability allows for the decryption of passwords using a pre-determined cryptographic key stored in another section of the firmware.

Understanding CVE-2019-15801

This CVE affects Zyxel GS1900 devices with firmware versions before 2.50(AAHH.0)C0.

What is CVE-2019-15801?

CVE-2019-15801 is a vulnerability in Zyxel GS1900 devices that allows for the decryption of encoded passwords used for user authentication.

The Impact of CVE-2019-15801

The vulnerability enables unauthorized access to diagnostic and password-recovery menus on affected devices, potentially compromising sensitive information.

Technical Details of CVE-2019-15801

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The issue is related to the fds_sys_passDebugPasswd_ret() and fds_sys_passRecoveryPasswd_ret() functions in libfds.so.0.0 on Zyxel GS1900 devices.

Affected Systems and Versions

Affected System: Zyxel GS1900 devices
Affected Versions: Firmware versions prior to 2.50(AAHH.0)C0

Exploitation Mechanism

By using the hardcoded cryptographic key found in the firmware, attackers can decrypt encoded passwords and gain unauthorized access to diagnostic and password-recovery menus.

Mitigation and Prevention

Protecting against CVE-2019-15801 involves taking immediate steps and implementing long-term security practices.

Immediate Steps to Take

Update firmware to version 2.50(AAHH.0)C0 or later to mitigate the vulnerability.
Monitor network activity for any unauthorized access attempts.

Long-Term Security Practices

Regularly update firmware and security patches to prevent future vulnerabilities.
Implement strong password policies and multi-factor authentication to enhance security.

Patching and Updates

Apply patches and updates provided by Zyxel to address the vulnerability and enhance device security.