CVE-2018-18709 : Exploit Details and Defense Strategies

A vulnerability has been identified in certain models of Tenda routers, including AC7 V15.03.06.44_CN, AC9 V15.03.05.19(6318)_CN, AC10 V15.03.06.23_CN, AC15 V15.03.05.19_CN, and AC18 V15.03.05.19(6318)_CN. The vulnerability arises from a buffer overflow issue in the routers' web server, known as httpd. Specifically, when a post request containing the "firewallEn" parameter is processed, its value is directly utilized in a strcpy function to assign it to a local variable stored on the stack. This action results in the overwrite of the function's return address.

Understanding CVE-2018-18709

This CVE entry describes a buffer overflow vulnerability in Tenda routers' web server, potentially allowing attackers to overwrite the function's return address.

What is CVE-2018-18709?

The vulnerability in Tenda routers allows malicious actors to exploit a buffer overflow issue in the httpd web server by manipulating the "firewallEn" parameter in a post request.

The Impact of CVE-2018-18709

The exploitation of this vulnerability could lead to a remote attacker executing arbitrary code on the affected router, potentially compromising the device and the network it is connected to.

Technical Details of CVE-2018-18709

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The vulnerability is a buffer overflow issue in the httpd web server of Tenda routers, triggered by processing the "firewallEn" parameter in a post request.

Affected Systems and Versions

Tenda AC7 V15.03.06.44_CN
Tenda AC9 V15.03.05.19(6318)_CN
Tenda AC10 V15.03.06.23_CN
Tenda AC15 V15.03.05.19_CN
Tenda AC18 V15.03.05.19(6318)_CN

Exploitation Mechanism

When the "firewallEn" parameter is processed in a post request, its value is directly used in a strcpy function, leading to a buffer overflow that overwrites the function's return address.

Mitigation and Prevention

Protecting systems from CVE-2018-18709 requires immediate actions and long-term security practices.

Immediate Steps to Take

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

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

Tenda router users should regularly check for firmware updates and apply them promptly to mitigate the risk of exploitation.