CVE-2021-20139 : Exploit Details and Defense Strategies

This article provides an overview of CVE-2021-20139, a critical unauthenticated command injection vulnerability found in Gryphon Tower routers.

Understanding CVE-2021-20139

CVE-2021-20139 is a severe security flaw that allows an unauthenticated attacker to execute commands as root on Gryphon Tower routers by exploiting the controller_server service.

What is CVE-2021-20139?

CVE-2021-20139 is an unauthenticated command injection vulnerability present in the controller_server service on Gryphon Tower routers. Attackers on the same network can leverage this flaw to run commands with root privileges on the device.

The Impact of CVE-2021-20139

The impact of this vulnerability is significant as it enables threat actors to execute malicious commands on affected routers, compromising the device's security and potentially leading to unauthorized access and control.

Technical Details of CVE-2021-20139

CVE-2021-20139 affects Gryphon Tower routers with versions less than or equal to 04.0004.12. The vulnerability resides in operation 3 parameters of the controller_server service.

Vulnerability Description

An unauthenticated command injection weakness in the controller_server service permits remote attackers to execute commands as root on the device. This can be achieved by sending a specially crafted packet to the service on port 9999.

Affected Systems and Versions

Gryphon Tower routers running firmware versions up to and including 04.0004.12 are vulnerable to CVE-2021-20139.

Exploitation Mechanism

The vulnerability is exploited by sending a malicious packet to the controller_server service on port 9999. Attackers can execute arbitrary commands on the device without the need for authentication.

Mitigation and Prevention

To safeguard against CVE-2021-20139, immediate action is crucial to prevent unauthorized access and compromise of Gryphon Tower routers.

Immediate Steps to Take

Users are advised to update their Gryphon Tower routers to a patched version that addresses the command injection vulnerability. Additionally, network segmentation and access controls can limit exposure to potential threats.

Long-Term Security Practices

Implementing strong network security measures, regular security audits, and staying informed about firmware updates and security advisories are essential for maintaining a secure network environment.

Patching and Updates

Regularly check for firmware updates and security patches released by Gryphon Tower for addressing CVE-2021-20139. Promptly applying these updates can mitigate the risks associated with the vulnerability.