A serious security vulnerability, known as CVE-2023-40800, has been discovered in Tenda AC23 v16.03.07.45_cn that could potentially be exploited by malicious actors. The compare_parentcontrol_time function of the device's firmware does not properly authenticate user input parameters, resulting in a post-authentication stack overflow vulnerability. This could potentially enable attackers to execute arbitrary code, gain unauthorized access, or even launch a denial of service. This post will discuss the details of this vulnerability, available exploits, and its impact.

Exploit Details

The root cause of the CVE-2023-40800 vulnerability lies in the compare_parentcontrol_time function of the Tenda AC23. The function is designed to compare parental control time settings, but it fails to sufficiently authenticate certain user input parameters during the process. This lack of input validation can lead to a stack overflow vulnerability, thereby enabling the execution of arbitrary code.

The affected function handles data passed via HTTP POST requests, and the vulnerable code snippet is as follows:

void compare_parentcontrol_time(char *input_time, char *parent_time)
{
    char user_input[64], parent_setting[64];

    strncpy(user_input, input_time, sizeof(user_input));
    strncpy(parent_setting, parent_time, sizeof(parent_setting));

    // Rest of the function...
}

The function copies the input_time (user input data) and parent_time (parental control time settings) into fixed-size character buffers user_input and parent_setting, each of which has a 64-byte size. However, there is no proper validation of the user input, which could result in a stack overflow if the user input data contains a larger string.

Original Reference

- Common Vulnerabilities and Exposures (CVE)

Impact

Successful exploitation of this vulnerability could allow attackers to execute arbitrary code with the privileges of the affected device, as well as potentially gain unauthorized access. This could lead to various malicious activities such as exfiltration of sensitive data, hijacking the targeted device, and launching denial of service attacks.

Mitigation Actions

Currently, there is no official patch or fix available for this specific vulnerability. However, users of the affected Tenda AC23 device can take a few precautionary steps to reduce exposure and mitigate risks:

1. Regularly check the manufacturer's website for firmware updates and promptly apply them when available.
2. Restrict external network access to the affected device and limit the usage of the device's management interface to trusted networks only.

Conclusion

The CVE-2023-40800 vulnerability, caused by the lack of user input validation in the compare_parentcontrol_time function, can pose significant risks to users of the Tenda AC23 v16.03.07.45_cn device. By understanding the vulnerability and its potential impact on the affected devices, users can take appropriate measures to minimize risks associated with this issue. Until an official patch is available, it is crucial for users to stay vigilant and implement the recommended mitigation actions to protect their devices and data from potential exploits.

Timeline

Published on: 08/25/2023 15:15:09 UTC
Last modified on: 08/29/2023 16:13:13 UTC