CVE-2023-40799 - Tenda AC23 Vv16.03.07.45_cn Buffer Overflow Vulnerability in sub_450A4C function

In recent years, we have seen a substantial increase in the exploitation of vulnerabilities found in router firmware. One such vulnerability, identified as CVE-2023-40799, has been discovered in Tenda AC23 routers. This vulnerability enables an attacker to perform a buffer overflow attack, potentially gaining unauthorized access to the router and its settings. In this post, we will take a detailed look at the vulnerability, and provide some insight into how it can be exploited. We will also present a code snippet, along with references to the original sources.

Description of Vulnerability

CVE-2023-40799 involves a vulnerability present in Tenda AC23 Vv16.03.07.45_cn router firmware. This firmware version is specifically vulnerable to a buffer overflow attack via the sub_450A4C function. A buffer overflow occurs when an application writes more data to a buffer than it has space to store. Consequently, the extra data overwrites the adjacent memory space, leading to various forms of harmful behavior, such as crashing the application or executing arbitrary code.

Exploit Details

The sub_450A4C function within Tenda AC23 Vv16.03.07.45_cn firmware is responsible for processing input data. Unfortunately, this function fails to validate the size of the input data correctly, allowing for a buffer overflow attack. An attacker can exploit this vulnerability by sending a crafted packet that causes an overflow, leading to the execution of arbitrary code.

Here's a code snippet that illustrates the vulnerability

int sub_450A4C(int a1) {
    int result = ;
    int v2 = a1;
    char v3 = ;
    char buffer[1024];
    int v5 = ;

    if (v2 > 1024) {
        result = -9;
    } else {
        memcpy(buffer, &v3, v2);
        result = ;
    }
    return result;
}

In this code snippet, the function sub_450A4C() takes an integer a1 as its input. The value of a1 determines the amount of data to be copied into the buffer. If a1 is larger than the size of the buffer (1024 bytes), it will cause a buffer overflow, leading to the execution of arbitrary code.

The original disclosure of this vulnerability can be found in the following references

1. Vulnerability in Tenda router firmware
2. CVE-2023-40799 at cvedetails.com

Mitigation

To mitigate this vulnerability, it is highly recommended that users update their Tenda AC23 Vv16.03.07.45_cn router firmware to the latest version. The firmware update should include a patch for the buffer overflow vulnerability present in the sub_450A4C function. Users can refer to the Tenda website for information on how to update their router firmware:

- Tenda Firmware Update Support

Conclusion

In conclusion, buffer overflow vulnerabilities such as CVE-2023-40799 can have a significant impact on the security and stability of network devices like routers. It is crucial to stay aware of any security updates and patches and to apply them as soon as possible. By doing so, users can minimize the potential risk of exploitation and protect their network devices from unauthorized access.

Timeline

Published on: 08/25/2023 15:15:09 UTC
Last modified on: 08/29/2023 16:05:17 UTC