CVE-2023-39665 - Buffer Overflow Vulnerability in D-Link DIR-868L Firmware

A new buffer overflow vulnerability has been discovered in the D-Link DIR-868L router firmware. The vulnerability, identified by CVE-2023-39665, targets the firmware version fw_revA_1-12_eu_multi_20170316. This issue is of particular concern to users of the D-Link DIR-868L router as it may allow attackers to gain unauthorized access, execute arbitrary code, and potentially gain full control of the device. In this post, we will analyze the exploit details along with a code snippet to showcase the vulnerability. We will also provide links to the original references for further reading.

Exploit Details

This vulnerability stems from a buffer overflow in the handling of the acStack_50 parameter within the D-Link DIR-868L firmware. A buffer overflow occurs when a program writes data beyond the allocated bounds of a memory buffer, leading to the overwrite of the adjacent memory, potentially causing the application to crash or execute arbitrary code. In this case, an attacker can exploit the acStack_50 parameter vulnerability to achieve remote code execution on the device.

Below is a code snippet demonstrating the vulnerability within the firmware

#include <stdio.h>
#include <string.h>

void vulnerable_function(char *acStack_50) {
  char buffer[50];

  strcpy(buffer, acStack_50); //Buffer overflow occurs here
}

int main() {
  char acStack_50[100];

  memset(acStack_50, 'A', 99);
  acStack_50[99] = '\';
  vulnerable_function(acStack_50);

  return ;
}

In the code snippet above, the vulnerable_function copies the contents of acStack_50 to a local buffer with a fixed size of 50 bytes using the strcpy function. However, if the input size exceeds the buffer size, a buffer overflow will occur, leading to potential exploitation by an attacker.

For more details about this vulnerability, please consult the following resources

1. D-Link DIR-868L (CVE-2023-39665) Vulnerability Advisory
2. D-Link DIR-868L Firmware Release Notes
3. NVD - CVE-2023-39665 Detail

Conclusion

D-Link DIR-868L router users running firmware version fw_revA_1-12_eu_multi_20170316 should be cautious of this buffer overflow vulnerability, CVE-2023-39665, affecting the acStack_50 parameter. It is crucial to always stay up-to-date with the latest firmware releases and security patches from the manufacturer to minimize risks of similar vulnerabilities. Additionally, it is essential to restrict access to your network router to prevent unauthorized access and maintain strong security measures.

Timeline

Published on: 08/18/2023 03:15:21 UTC
Last modified on: 11/07/2023 04:17:36 UTC