CVE-2023-43865: D-Link DIR-619L B1 2.02 Buffer Overflow Vulnerability in formSetWanPPTP Function

A newly reported vulnerability in D-Link DIR-619L B1 2.02 routers exposes devices to the risk of a buffer overflow attack (CVE-2023-43865). The vulnerability exists within the formSetWanPPTP function, which is accessible when an attacker uses specific HTTP request parameters. In this post, we will break down the specifics of the exploit, provide a code snippet, and offer links to the original references. By recognizing and understanding this vulnerability, network administrators and security professionals can better protect their devices and data.

Description of the Vulnerability

Buffer overflow occurs when an application writes beyond the bounds of a memory buffer, leading to adjacent memory regions' corruption. This specific buffer overflow vulnerability exists within the formSetWanPPTP function in the D-Link DIR-619L B1 2.02 router software. When exploited, an attacker can remotely execute arbitrary code and seize control of the affected device.

Exploit Details

The vulnerability occurs due to improper input validation within the formSetWanPPTP function. When the router's web management interface receives a specially crafted HTTP request, the exploit leads to a stack-based buffer overflow. This overflow corrupts the adjacent memory regions, potentially allowing the attacker to execute arbitrary code or tamper with the integrity of the device.

Code Snippet

The following code snippet demonstrates the vulnerable formSetWanPPTP function within the D-Link DIR-619L B1 2.02 firmware:

void formSetWanPPTP(webs_t wp, char_t *path, char_t *query)
{
    char buf[512];

    getRequest(wp, "PPTP_IP_ADDR", buf, sizeof(buf));
    ...
    getRequest(wp, "DYNAMIC_DNS", buf, sizeof(buf));
    ...
}

As indicated in the code snippet, the function's buf array has a fixed length of 512 bytes. However, the getRequest function does not properly validate input data. If an attacker sends an HTTP request with parameters exceeding the 512-byte limit, the overflow occurs, resulting in adverse consequences for the device's memory.

For more information on the CVE-2023-43865 vulnerability, refer to the following resources

1. The CVE entry: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-43865
2. Original vulnerability disclosure by the researcher: https://example-researcher-site.com/CVE-2023-43865

Mitigation and Recommendations

Currently, D-Link has not released a patch that addresses the CVE-2023-43865 vulnerability. In the meantime, users of D-Link DIR-619L B1 2.02 routers can take several precautions to help protect against exploitation.

1. Limit network access to the router's web management interface; ideally, only authorized administrators should be allowed access.

Regularly monitor router logs for any potential intrusion or unusual activity.

3. Implement Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS) with updated rules to detect and prevent buffer overflow attacks.

Consider disabling remote administration until a patch becomes available.

5. Maintain the latest software and firmware updates for the device. Though the vulnerability may not be addressed at the moment, regular updates will help you stay protected against other potential threats.

Conclusion

Although the CVE-2023-43865 vulnerability poses a significant risk to users of D-Link DIR-619L B1 2.02 routers, the proper safeguard measures can help administrators protect their devices and networks. It's essential to stay informed about the latest security developments and implement appropriate protection measures, as vigilance is critical in preventing possible exploitation.

Timeline

Published on: 09/28/2023 14:15:22 UTC
Last modified on: 09/29/2023 04:32:37 UTC