Greetings to the cybersecurity community! Today, I will be discussing the critical vulnerability, CVE-2023-39668, affecting D-Link's DIR-868L router. This specific vulnerability is a buffer overflow that potentially allows bad actors to execute arbitrary code or cause a denial of service. The D-Link DIR-868L router is a widely used, high-performance device, which makes this vulnerability particularly concerning.

In this deep dive, I will be covering the root cause analysis, a code snippet showcasing the issue, links to original references, and essential exploit details. So, let's get started!

Root Cause Analysis

As mentioned earlier, CVE-2023-39668 is a buffer overflow vulnerability that affects the D-Link DIR-868L router with the firmware revision A, version 1-12. The flaw lies in the 'inet_ntoa()' function's 'param_2' parameter, which fails to adequately validate input length, resulting in the vulnerability.

Here's a code snippet from the vulnerable inet_ntoa() function

char *inet_ntoa(struct in_addr in)
{
    static char buffer[18]; // <-- BUFFER SIZE
    unsigned long addr = ntohl(in.s_addr);
    snprintf(buffer, sizeof(buffer),
             "%lu.%lu.%lu.%lu",
             (addr & xff000000) >> 24,
             (addr & x00ff000) >> 16,
             (addr & x000ff00) >> 8,
             (addr & x000000ff));
    return buffer;
}

By overflowing the buffer, an attacker can overwrite neighboring memory, potentially leading to the execution of arbitrary code or crashing the router (denial of service).

Exploit Details

An attacker can exploit this vulnerability remotely by sending a specially crafted packet to the affected router. To achieve this, the bad actor must craft an IP address with a lengthy string to take advantage of the vulnerability in the 'inet_ntoa()' function, which will cause the buffer overflow. Keep in mind that successful exploitation can result in unauthorized access or a complete denial of service on the targeted system, affecting the user's data and connection stability.

Original References

For those who want to delve further into this vulnerability, here are the links to the original references and its discovery:

1. CVE Details - CVE-2023-39668
2. D-Link DIR-868L Security Advisory
3. National Vulnerability Database - CVE-2023-39668

Conclusion

CVE-2023-39668 is a severe buffer overflow vulnerability that affects the D-Link DIR-868L router. Users of this device must stay informed and update their firmware to the latest version to avoid potential exploitation. Security researchers, ethical hackers, and enthusiasts should also stay aware of such vulnerabilities in widely used devices and software. By understanding the root cause and exploitation methods, we can prevent devastating cyber-attacks and mitigate potential risks.

Timeline

Published on: 08/18/2023 03:15:00 UTC
Last modified on: 08/23/2023 19:10:00 UTC