CVE-2020-13391 Explained : Impact and Mitigation

An issue was discovered on Tenda AC6 V1.0 V15.03.05.19_multi_TD01, AC9 V1.0 V15.03.05.19(6318)CN, AC9 V3.0 V15.03.06.42_multi, AC15 V1.0 V15.03.05.19_multi_TD01, and AC18 V15.03.05.19(6318)_CN devices. There is a buffer overflow vulnerability in the router's web server -- httpd. An attacker can exploit this vulnerability to execute arbitrary code.

Understanding CVE-2020-13391

This CVE identifies a buffer overflow vulnerability in Tenda routers that can be exploited by attackers to execute arbitrary code.

What is CVE-2020-13391?

The vulnerability exists in the router's web server, specifically in the processing of the /goform/SetSpeedWan speed_dir parameter for a POST request. By manipulating this parameter, an attacker can overwrite the return address of a function, leading to arbitrary code execution.

The Impact of CVE-2020-13391

The exploitation of this vulnerability can result in attackers executing arbitrary code on the affected Tenda routers, potentially leading to unauthorized access, data theft, or further network compromise.

Technical Details of CVE-2020-13391

This section provides more technical insights into the vulnerability.

Vulnerability Description

The vulnerability is a buffer overflow issue in the httpd web server of Tenda routers. It occurs when processing the speed_dir parameter, allowing attackers to overwrite the function's return address.

Affected Systems and Versions

Tenda AC6 V1.0 V15.03.05.19_multi_TD01
Tenda AC9 V1.0 V15.03.05.19(6318)_CN
Tenda AC9 V3.0 V15.03.06.42_multi
Tenda AC15 V1.0 V15.03.05.19_multi_TD01
Tenda AC18 V15.03.05.19(6318_)_CN

Exploitation Mechanism

Attackers can exploit the vulnerability by crafting a malicious payload to manipulate the speed_dir parameter, triggering the buffer overflow and enabling the execution of arbitrary code.

Mitigation and Prevention

Protecting systems from CVE-2020-13391 requires immediate actions and long-term security measures.

Immediate Steps to Take

Apply security patches provided by Tenda to address the vulnerability.
Monitor network traffic for any suspicious activities that may indicate exploitation attempts.

Long-Term Security Practices

Regularly update router firmware to ensure the latest security fixes are in place.
Implement network segmentation to limit the impact of potential attacks.

Patching and Updates

Stay informed about security advisories from Tenda and promptly apply any released patches to mitigate the vulnerability.