CVE-2021-4039 : Exploit Details and Defense Strategies

A command injection vulnerability in the web interface of the Zyxel NWA-1100-NH firmware could allow an attacker to execute arbitrary OS commands on the device.

Understanding CVE-2021-4039

This CVE highlights a critical command injection vulnerability in Zyxel NWA-1100-NH firmware that poses a significant risk to affected systems.

What is CVE-2021-4039?

The CVE-2021-4039 vulnerability pertains to the improper neutralization of special elements in OS commands, allowing threat actors to execute malicious commands via the device's web interface.

The Impact of CVE-2021-4039

With a CVSS base score of 9.8 (Critical), this vulnerability has a high impact on confidentiality, integrity, and availability, making it crucial to address promptly.

Technical Details of CVE-2021-4039

The technical details shed light on the specifics of the vulnerability, affected systems, and exploitation mechanisms.

Vulnerability Description

The vulnerability allows attackers to inject and execute arbitrary OS commands on the Zyxel NWA-1100-NH device, posing a serious security risk.

Affected Systems and Versions

Zyxel NWA-1100-NH firmware version 2.12(AASI.0)C0 is affected by this vulnerability, putting devices with this version at risk.

Exploitation Mechanism

Exploiting this vulnerability involves sending crafted commands via the web interface, enabling unauthorized remote code execution.

Mitigation and Prevention

Addressing CVE-2021-4039 requires immediate action and the implementation of long-term security measures.

Immediate Steps to Take

Update the firmware to the latest secure version provided by Zyxel to patch the vulnerability.
Limit access to the device's web interface and ensure proper network segmentation.

Long-Term Security Practices

Regularly monitor for security advisories and updates from Zyxel to stay informed about potential vulnerabilities.
Conduct security assessments and penetration testing to identify and remediate any weaknesses.

Patching and Updates

Regularly apply security patches and firmware updates from Zyxel to protect systems from known vulnerabilities.