Hello to all security enthusiasts and fellow researchers! Today we will be discussing CVE-2023-25556, a vulnerability belonging to the CWE-287: Improper Authentication category. This vulnerability targets smart homes and building automation systems running on the KNX protocol.

As we all know, ensuring proper security and privacy in smart homes have become a crucial concern. With the enormous amount of sensitive data and control that these systems provide, it's no wonder that attackers have set their eyes on exploiting them.

In this article, we will delve into the specifics of this vulnerability, explain how an attacker could exploit it, and share a code snippet as an example. Furthermore, we will be providing links to the original sources so that you can investigate more deeply about the subject if you wish.

Exploit Details

CVE-2023-25556 is a vulnerability that exists due to the improper authentication mechanism used when entering a passkey into a KNX installation. Specifically, this vulnerability affects installations that are authorized by using a key of fewer than seven digits.

The attack scenario occurs when an attacker gains physical access to the KNX system and tries to exploit the vulnerability. An attacker could attempt entering codes with the passkey's length they know, and if it is less than 7 digits, they have a higher chance of bypassing the authentication and gaining unauthorized access to the system.

Here's a simple code snippet to help visualize the attack

import itertools

def knx_bruteforce(passkey_length):
    digits = '0123456789'
    possible_keys = itertools.product(digits, repeat=passkey_length)

    for key_attempt in possible_keys:
        key_string = ''.join(key_attempt)
        if authenticate(key_string):
            print(f'Access granted with key: {key_string}')
            break

This snippet demonstrates how an attacker can use brute-force to attempt and find the correct key by simply trying out all possible key combinations. Since the key is less than 7 digits, the total number of possible keys reduces significantly, making the brute-force attack feasible.

Original References

-MITRE CVE reference: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-25556

-National Vulnerability Database: https://nvd.nist.gov/vuln/detail/CVE-2023-25556

-CWE-287: Improper Authentication: https://cwe.mitre.org/data/definitions/287.html

-KNX Association: http://www.knx.org/

To protect your KNX installations from this vulnerability, we strongly recommend the following steps

1. Ensure that all keys used in your KNX system are at least 7 digits long, which will significantly increase the difficulty of brute-force attempts.

Limit and monitor physical access to your KNX installation to prevent unauthorized access.

3. Regularly review and update the security settings and protocols used in your smart home or building automation system.
4. Stay informed about the latest security updates and vulnerabilities in the field of smart home security.

Conclusion

CVE-2023-25556 is a serious vulnerability that highlights the importance of proper authentication mechanisms and key management in KNX installations. By keeping track of the latest security updates and implementing best practices, we can protect our smart homes and building automation systems from unauthorized access. Stay safe, and happy researching!

Timeline

Published on: 04/18/2023 18:15:00 UTC
Last modified on: 04/28/2023 13:36:00 UTC