CVE-2023-27989 : Exploit Details and Defense Strategies

This CVE record, assigned by Zyxel, was published on June 5, 2023, and involves a buffer overflow vulnerability in the NR7101 firmware.

Understanding CVE-2023-27989

This section will delve into the specifics of CVE-2023-27989, highlighting its impact, technical details, and mitigation strategies.

What is CVE-2023-27989?

CVE-2023-27989 is a buffer overflow vulnerability found in the CGI program of Zyxel NR7101 firmware versions prior to V1.00(ABUV.8)C0. This flaw could be exploited by a remote authenticated attacker to trigger denial of service (DoS) conditions by sending a specially crafted HTTP request to the vulnerable device.

The Impact of CVE-2023-27989

The vulnerability poses a medium severity risk with a CVSS base score of 6.5. It has a high impact on availability but does not affect confidentiality or integrity. With a low attack complexity and privileges required, an attacker with network access could potentially exploit this vulnerability.

Technical Details of CVE-2023-27989

Let's explore the technical aspects of CVE-2023-27989, including its vulnerability description, affected systems and versions, and exploitation mechanism.

Vulnerability Description

The vulnerability arises from a buffer overflow issue in the CGI program of Zyxel NR7101 firmware versions before V1.00(ABUV.8)C0. An attacker could exploit this flaw to execute a DoS attack on the affected device.

Affected Systems and Versions

The CVE affects Zyxel NR7101 firmware versions earlier than V1.00(ABUV.8)C0.

Exploitation Mechanism

By sending a specifically crafted HTTP request to the vulnerable Zyxel NR7101 device, a remote authenticated attacker could exploit the buffer overflow vulnerability and cause a denial of service.

Mitigation and Prevention

In response to CVE-2023-27989, it is crucial for users and administrators to take immediate action to secure their systems and prevent potential attacks.

Immediate Steps to Take

Ensure that the Zyxel NR7101 firmware is updated to version V1.00(ABUV.8)C0 or higher to mitigate the vulnerability.
Monitor network traffic and look for any signs of exploitation.

Long-Term Security Practices

Regularly update firmware and software to patch known vulnerabilities.
Implement network segmentation to limit the impact of potential attacks.
Employ strong authentication mechanisms and access controls.

Patching and Updates

Zyxel has likely released patches or updates to address the buffer overflow vulnerability in the affected NR7101 firmware versions. It is advisable to promptly apply these patches to safeguard against potential exploitation.