CVE-2021-33271 Explained : Impact and Mitigation

D-Link DIR-809 devices with firmware through DIR-809Ax_FW1.12WWB03_20190410 contain a stack buffer overflow vulnerability triggered by a crafted POST request.

Understanding CVE-2021-33271

This article discusses the impact, technical details, and mitigation strategies for CVE-2021-33271.

What is CVE-2021-33271?

CVE-2021-33271 is a stack buffer overflow vulnerability found in D-Link DIR-809 devices with specific firmware versions. It can be exploited through a carefully crafted POST request.

The Impact of CVE-2021-33271

The vulnerability allows attackers to execute arbitrary code or crash the affected device, potentially leading to a denial of service (DoS) condition or complete compromise of the device.

Technical Details of CVE-2021-33271

The following section outlines the vulnerability description, affected systems, versions, and exploitation mechanism.

Vulnerability Description

The vulnerability exists in the function sub_80046EB4 within /formSetPortTr of the affected D-Link DIR-809 firmware versions. It can result in a stack buffer overflow when processing specially crafted POST requests.

Affected Systems and Versions

D-Link DIR-809 devices running firmware through DIR-809Ax_FW1.12WWB03_20190410 are affected by CVE-2021-33271. Users with these versions are at risk of exploitation.

Exploitation Mechanism

By sending a maliciously constructed POST request, threat actors can trigger the stack buffer overflow vulnerability in D-Link DIR-809 devices, potentially gaining unauthorized access or causing a system crash.

Mitigation and Prevention

In response to CVE-2021-33271, users are advised to take immediate action and implement long-term security measures to safeguard their devices.

Immediate Steps to Take

Ensure the firmware of D-Link DIR-809 devices is updated to a secure version that addresses the stack buffer overflow vulnerability. Disable any unnecessary services that could be leveraged by attackers.

Long-Term Security Practices

Regularly monitor security bulletins from D-Link and apply recommended patches promptly. Implement network segmentation and access controls to limit the impact of potential security incidents.

Patching and Updates

Stay informed about security updates and patches released by D-Link for the DIR-809 devices. Timely installation of patches can help mitigate the risk of exploitation and enhance the overall security posture.