CVE-2021-35028 : Security Advisory and Response

A command injection vulnerability in the CGI program of the Zyxel VPN2S firmware version 1.12 could allow an authenticated, local user to execute arbitrary OS commands.

Understanding CVE-2021-35028

This CVE identifier is associated with a high-severity command injection vulnerability affecting Zyxel's ZyWALL VPN2S Firmware.

What is CVE-2021-35028?

CVE-2021-35028 is a security flaw in the Zyxel VPN2S firmware that enables an authenticated, local user to run unauthorized OS commands through the device's CGI program.

The Impact of CVE-2021-35028

With a CVSS base score of 7.3, this vulnerability poses a high risk, allowing attackers to compromise the confidentiality, integrity, and availability of affected systems.

Technical Details of CVE-2021-35028

This section delves into the specifics of the vulnerability.

Vulnerability Description

The vulnerability stems from improper neutralization of special elements in OS commands, leading to command injection via the CGI program in ZyWALL VPN2S Firmware.

Affected Systems and Versions

Zyxel's ZyWALL VPN2S Firmware version 1.12 (1.12(ABLN.0)C0) is impacted by this security issue.

Exploitation Mechanism

Attackers must be authenticated and local to exploit this vulnerability, requiring high privileges and user interaction.

Mitigation and Prevention

To safeguard systems against CVE-2021-35028, follow these recommendations.

Immediate Steps to Take

Update to the latest patched version of ZyWALL VPN2S Firmware to mitigate the risk of exploitation.
Restrict network access to authorized users to minimize the attack surface.

Long-Term Security Practices

Regularly monitor security advisories from Zyxel and apply patches promptly.
Implement strong access controls and user authentication mechanisms.

Patching and Updates

Stay informed about security updates and implement them as soon as they are available to ensure protection against known vulnerabilities.