CVE-2023-4397 : Vulnerability Insights and Analysis

This CVE, assigned by Zyxel, pertains to a buffer overflow vulnerability found in multiple firmware versions of Zyxel products, including the ATP series, USG FLEX series, USG FLEX 50(W) series, and USG20(W)-VPN series. The vulnerability could be exploited by an authenticated local attacker with administrator privileges to trigger denial-of-service (DoS) conditions by executing specially crafted CLI commands on the affected device.

Understanding CVE-2023-4397

This section delves into the details and impact of CVE-2023-4397, providing insights into the vulnerability, its impact, technical details, affected systems, and mitigation strategies.

What is CVE-2023-4397?

CVE-2023-4397 is a buffer overflow vulnerability affecting select Zyxel firmware versions, allowing authenticated local attackers to exploit the flaw to cause denial-of-service conditions on the targeted device.

The Impact of CVE-2023-4397

With a CVSS v3.1 base score of 4.4 (Medium severity), this vulnerability poses a significant risk to affected Zyxel devices. The attack vector is local, requiring high privileges, and could lead to a disruption in availability if exploited successfully.

Technical Details of CVE-2023-4397

Exploring the vulnerability's technical aspects, including its description, affected systems, and the exploitation mechanism.

Vulnerability Description

The buffer overflow vulnerability in Zyxel firmware versions allows an authenticated local attacker to execute crafted CLI commands, leading to a buffer overflow condition and subsequent denial-of-service on the affected device.

Affected Systems and Versions

The following Zyxel firmware versions are impacted by CVE-2023-4397:

ATP series firmware version 5.37
USG FLEX series firmware version 5.37
USG FLEX 50(W) series firmware version 5.37
USG20(W)-VPN series firmware version 5.37

Exploitation Mechanism

By leveraging the vulnerability in the affected firmware versions, an authenticated local attacker with administrator privileges can exploit the buffer overflow flaw by executing malicious CLI commands on the device.

Mitigation and Prevention

Taking proactive steps to mitigate the risk posed by CVE-2023-4397, safeguarding Zyxel devices from potential exploitation and minimizing the impact of the vulnerability.

Immediate Steps to Take

Organizations should apply security patches or updates provided by Zyxel to address the vulnerability.
Restricting access to privileged CLI commands can help prevent unauthorized exploitation of the buffer overflow issue.

Long-Term Security Practices

Regularly monitor vendor-specific security advisories and apply patches promptly to mitigate future vulnerabilities.
Conduct routine security assessments and audits to identify and address potential weaknesses in network devices.

Patching and Updates

Stay informed about security updates and patches released by Zyxel for the affected firmware versions to mitigate CVE-2023-4397. Regularly update and maintain the firmware of Zyxel devices to ensure optimal security posture and protection against emerging threats.