CVE-2023-44837 - Buffer Overflow in D-Link DIR-823G A1V1..2B05 Leading to Denial of Service Attacks

Summary: A buffer overflow vulnerability in the D-Link DIR-823G A1V1..2B05 router firmware has been discovered, allowing potential attackers to trigger Denial of Service (DoS) attacks. This critical vulnerability, dubbed "CVE-2023-44837", was found within the "SetWanSettings" function and is caused by improper handling of the "Password" parameter. In this post, we'll discuss the exploit in detail and provide references to the original sources and additional insight.

Exploit Details

The DIR-823G router from D-Link is a common home and small office networking device. The vulnerability discovered by security researchers lies within the firmware version A1V1..2B05, specifically in the "SetWanSettings" function. This function accepts a "Password" parameter, which is used to authenticate the user's credentials. However, the "Password" parameter is mishandled and improperly validated, leading to the possibility of a buffer overflow.

The buffer overflow occurs when inputting a large enough password to the "SetWanSettings" function, causing memory to be overwritten. The memory corruption can consequently lead to DoS attacks by the adversarial party.

Here's a simplified code snippet that showcases the vulnerable function

int SetWanSettings(char *password) {
    char buf[256];

    strncpy(buf, password, sizeof(buf));
    // ... further processing ...
}

The issue here is that the strncpy() function does not properly limit the input length to the available buffer's size, which results in a buffer overflow.

Mitigation

To properly mitigate this vulnerability, D-Link should limit the input password length to the intended buffer size. This can be achieved by replacing the strncpy() function with the safer snprintf() function:

int SetWanSettings(char *password) {
    char buf[256];

    snprintf(buf, sizeof(buf), "%s", password);
    // ... further processing ...
}

In the meantime, users running the A1V1..2B05 firmware version should check D-Link's official website regularly for firmware updates containing a patch for this vulnerability.

External References

- CVE-2023-44837 - The official CVE entry for this vulnerability.
- D-Link Support - Keep an eye on D-Link's support website for firmware updates.

In conclusion, security researchers have discovered a buffer overflow vulnerability in the D-Link DIR-823G A1V1..2B05 router firmware, which allows potential attackers to trigger DoS attacks. Users are advised to update their router's firmware to the latest version as soon as a fix is available.

Timeline

Published on: 10/05/2023 16:15:12 UTC
Last modified on: 10/06/2023 15:19:36 UTC